- Blood Tests That Help Explain Stroke
- Early testing after stroke
- Brain scans
- Heart tests
- Blood tests
- Other tests
- Prognostic Value of Complete Blood Count and Electrolyte Panel during Emergency Department Evaluation for Acute Ischemic Stroke
- Is there an early warning test for stroke?
- How is a stroke diagnosed and evaluated?
- Stroke patients not getting vital test to see if they can swallow, study finds
- Test needed even in people with mild stroke
- Screening efforts need improvement
Blood Tests That Help Explain Stroke
If you’ve suffered a stroke or have had symptoms of a stroke, you need to be fully evaluated by a doctor to get the right diagnosis and treatment. In the course of evaluating a patient who is suspected of having a stroke, doctors will conduct a number of different types of blood tests as well as a physical and neurological exam and imaging tests.
Though blood tests cannot definitively diagnose a stroke, they do help give the doctor a picture of what may caused the stroke.
Diagnosing Stroke: What Blood Tests May Reveal
Doctors will take a blood sample and run the following tests when trying to diagnose stroke:
- CBC, or complete blood count, measures the number of platelets and red and white cells in your blood. CBC results can suggest certain conditions that may or may not be associated with a stroke, such as anemia or an infection.
- Blood lipid tests measures your cholesterol levels — both the bad (low-density lipoprotein, or LDL) and the good (high-density lipoprotein, or HDL). High cholesterol is a major risk factor for stroke and may indicate that you are at greater risk of having a stroke.
- Coagulation tests, including prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR), check the speed at which your blood clots. Any irregularity may indicate an increased risk of stroke. Abnormal bleeding is a potential cause of hemorrhagic stroke (caused by bleeding in the brain); abnormal clotting is a potential cause of ischemic stroke (clot in an artery in the brain). Doctors need to know how quickly or slowly your blood is clotting to help them determine how best to treat a stroke without causing any damage.
- Blood chemistry tests check the amounts of several substances produced by the body that are found in the blood. Doctors will check your level of glucose, or sugar, which, if abnormally high or abnormally low, may actually cause symptoms that are similar to stroke. Blood chemistry tests also check levels of electrolytes (ions that conduct electricity) in your blood, and may be able to give a warning if your organs are not working properly.
- Homocysteine level tests check the level of the amino acid homocysteine in the blood, which is thought to contribute to increased stroke risk and atherosclerosis, a known risk factor for stroke.
- CRP level tests looks at C-reactive protein, a marker of inflammation that, if high, may indicate increased risk for cardiovascular disease and stroke.
Diagnosing Stroke: More Specific Blood Tests
If doctors aren’t able to diagnose a stroke or determine what caused it from initial tests, they may run these more specific blood tests:
- An antinuclear antibody test, or ANA, is used to rule out an autoimmune disease as the cause of your symptoms.
- An antiphospholipid antibodies test, or APA, will determine if antibodies that increase the risk of a blood clot are found in your blood. Anticardiolipin antibodies (ACL) and lupus anticoagulant (LA) tests may also be given for the same reason.
- Cardiac enzyme tests, including LDH isoenzymes, creatine kinase, and troponin tests, determine whether a myocardial infarction ( heart attack) has occurred.
- Tests for drugs and alcohol levels may be done to check for foreign substances in your blood that can produce stroke-like symptoms.
Blood tests are vital in evaluating a possible stroke. The results can help pinpoint the risk factors for stroke and, at the same time, help to eliminate other possible medical conditions that might be causing stroke-like symptoms.
Early testing after stroke
An ambulance will take you straight to a hospital where you should be assessed as a priority. The doctors will do some tests to:
- make sure the symptoms are definitely due to stroke
- work out the type of stroke
- find out what area of the brain was affected
- work out how severe the impact of the stroke was on the brain
- if possible, find out and start treating the cause of the stroke.
Everyone will need a different set of tests. Common tests include:
Computerised tomography (CT scan) and magnetic resonance imaging (MRI) take pictures of your brain that show areas of damage and swelling. Either a CT scan or MRI should be done urgently within the first 24 hours after a stroke. This is to work out the type of stroke (ischaemic or haemorrhagic).
They may be repeated later to see how much of the brain has been affected by the stroke, or if you are getting worse.
An electrocardiogram (ECG) is a test for abnormal heart rhythm or heart disease. This test is recommended for all stroke patients.
An echocardiogram is an ultrasound to check for a clot or enlargement of a chamber in your heart.
There is no specific blood test for stroke. Blood tests are used to rule out other medical conditions and help the doctors decide the best treatment.
The most common blood tests will measure:
- the clotting ability of your blood (international normalised ratio or INR)
- fasting lipids (cholesterol) level
- renal (kidney) function
- glucose (blood sugar) levels
- electrolytes balance (salt levels)
- leukocyte (white blood cell) count
- haematocrit (iron) levels
- erythrocite sedimentation rate and c-reactive protein (as measures of inflammation in the body).
In the early days in hospital, other tests that may be performed include:
- Transcranial Doppler (TCD) – an ultrasound that measures the speed of the blood flow in the brain arteries. This can help identify areas of slow blood flow in the brain.
- Cerebral angiogram – a catheter is placed in an artery and used to inject a special dye (contrast material). X-ray images are taken to see how the dye moves through the artery and blood vessels of the brain. This dye helps show any blockages in blood flow.
- Carotid duplex (also called a doppler) – an ultrasound that looks at neck arteries. It can tell if these arteries are narrow or partially blocked.
- Urine tests or chest X-rays may also be done to check for infection or other disease.
Regular observations will also be taken to monitor blood pressure, pulse (heart rate), temperature, blood sugar levels, oxygen levels and breathing pattern.
It is important that you ask questions during early testing after stroke, to help you understand the tests you have and the results. For example:
What What is the test for and why is it being done?
Who Who will be doing it?
When When will I find out how it went?
Explain Who will explain the results to me and/or my family?
Depending on the test results, you may be given emergency treatment for the stroke.
How likely are you to have a heart attack or stroke? A simple blood test can help predict your risk.
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The PLAC® Test measures an enzyme, Lp-PLA2, that is produced when your arteries are inflamed and plaque (fatty buildup) is at risk of rupturing. When a rupture occurs, a blood clot forms over it, sometimes blocking the artery. That’s what causes most heart attacks and certain types of strokes.
You can’t feel artery inflammation, but a PLAC Test can sense it for you. The higher your Lp-PLA2 enzyme, the higher your risk for heart attack or stroke.
Know when to step up preventive care
For patients visiting the Preventive Cardiology Clinic at Cleveland Clinic, the PLAC Test is a standard tool, part of their panel of inflammation and advanced cardiovascular disease risk blood tests.
“We use it particularly for patients with intermediate risk, for whom we’re not already using the most aggressive risk-reduction efforts,” says Stanley Hazen, MD, PhD, Section Head of Preventive Cardiology and Rehabilitation. “If levels are elevated, we intensify preventive efforts.”
It’s a blood test that can help predict stroke risk, he notes.
“Clearly high blood pressure is a major risk factor for stroke, but measuring blood pressure alone is not sufficient to capture those at increased risk,” said Dr. Hazen in a recent Parade magazine article about the PLAC Test.
Other screenings still important
The PLAC Test isn’t intended to be used alone. You still need regular cholesterol tests, blood pressure checks and screenings for diabetes and other cardiovascular risk factors. But PLAC Test results can give your doctor extra information about the health of your arteries, which can help identify the best treatment for you — especially if your cardiovascular risk before was uncertain.
“When we know a patient’s risk of having a cardiovascular event, we get one step closer to preventing it,” says Dr. Hazen.
Sources Used in Current Review
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA .
Klausner HA, Lewandowski C. Infrequent causes of stroke. Emerg Med Clinics of North Amer 20:657, 2002.
Chalel JA, Merino JG, Warach S. Update on stroke. Curr Opin Neurol 17:447, 2004.
Harrison’s Principles of Internal Medicine, 16th Ed. Kasper DL, et al., Eds. McGraw-Hill Companies. 2005.
The Internet Stroke Center: Blood Tests and Procedures Used for Stroke Diagnosis. Available online at http://www.strokecenter.org/pat/diagnosis/blood_tests.htm. Accessed May 2008.
National Institute of Neurological Disorders and Stroke. Stroke Information Page. Available online at http://www.ninds.nih.gov/disorders/stroke/stroke.htm. Accessed May 2008.
National Institute of Neurological Disorders and Stroke. Stroke Information Page. Available online at http://www.ninds.nih.gov/disorders/stroke/stroke.htm. Accessed September 2011.
American Stroke Association. Understanding Risk. Available online at http://www.strokeassociation.org/STROKEORG/AboutStroke/UnderstandingRisk/Understanding-Risk_UCM_308539_SubHomePage.jsp. Accessed September 2011.
Hijazi, Z et al. Abstract 13472: NT-proBNP is Prognostic for Stroke and Death in Atrial Fibrillation – a RELY Substudy. Circulation November 2010, 122 (Meeting Abstract Supplement). Available online at http://circ.ahajournals.org/cgi/content/meeting_abstract/122/21_MeetingAbstracts/A13472. Accessed September 2011.
Prognostic Value of Complete Blood Count and Electrolyte Panel during Emergency Department Evaluation for Acute Ischemic Stroke
Objective. To determine whether routine laboratory parameters are predictors of early mortality after acute ischemic stroke (AIS). Methods. The cohort consisted of 522 consecutive patients with AIS presenting to the emergency department (ED) at a tertiary referral center during a 27-month period, residing within the surrounding ten counties. Serum laboratory values were obtained for all patients and categorized according to whether the levels were low, normal, or high. These laboratory results were evaluated as potential predictors of 90-day mortality using Cox proportional hazards models. The associations were summarized by calculating risk ratios (RRs) and 95% confidence intervals (CI). Results. The presence of elevated white blood cell count (RR 2.2, 95% CI 1.5–3.4), low bicarbonate (RR 4.2, 95% CI 2.6–6.7), low calcium (RR 2.9, 95% CI 1.4–5.9), and high glucose (RR 1.3, 95% 1.1–1.6) were each univariately associated with significantly higher mortality within the first 90 days. Based on fitting a multivariate Cox regression model, elevated white blood cell count, low bicarbonate, and high glucose were each identified as being jointly associated with early mortality ( ). Conclusion. Early leukocytosis, acidosis, and hyperglycemia and hypocalcemia in AIS appear to be associated with early mortality. Whether addressing these factors will impact survival remains to be investigated.
For patients who present with chief complaint of acute ischemic stroke, the American Stroke Association recommends a set of diagnostic studies to be done at presentation, with the intent of optimizing and expediting the care of these patients. From the Emergency Physicians’ perspective many tests are simply part of a routine battery, often without direct impact on emergency department (ED) management, diagnostic or prognostic value. In this study, we sought to determine whether the routine complete blood count (CBC) and electrolyte panel include any components that are markers of early mortality in acute ischemic stroke. Specifically, the parameters of interest were those obtained as part of routine clinical investigation.
2.1. Study Design
This study was an observational study using a consecutive sample of local residents presenting to the ED with acute ischemic stroke (AIS). The primary outcome measure was death at 90 days. This study was approved by the Mayo Clinic Institutional Review Board.
2.2. Study Population and Setting
This study was conducted at the Saint Marys Hospital, a tertiary referral academic medical center with an annual ED census of 70,000 in Rochester, MN. The initial study population consisted of all 723 consecutive patients presenting to the ED with AIS (ICD-9-CM codes 433–437) between December 2001 and March 2004. For purposes of follow-up, this sample was limited to the 541 patients who resided in the local county and the surrounding 9 county areas. Among these 541, 19 patients denied research authorization and were therefore excluded from further study.
2.3. Study Protocol
The method of patient enrollment was consecutive, and written research authorization was obtained from all patients. All patients regardless of whether they were part of the study or not had standard labs drawn as part of our ED’s acute stroke care practice protocol. Our standard practice protocol also includes careful attention to vital sign monitoring, immediate head CT, and neurologic consultation.
Serum laboratory values were obtained in 521 of the 522 patients (one patient was admitted directly to the hospital). The complete blood count (CBC) was performed using the Coulter LH750, an impedance cell counter (Coulter Systems Reference Guide, Beckman-Coulter Corporation, Miami, FL.) The electrolyte panel which includes sodium, potassium, chloride, and bicarbonate was performed using Nova Biomedical M3099859 electrolyte/chemistry analyzer (Nova Biomedical Corp., Waltham, MA). The serum calcium which is frequently collected in addition to standard electrolytes for stroke and cardiac patients was performed using A Copenhagen ABL 700 series Radiometer (Radiometer Medical, Copenhagen, Denmark). Laboratory values were categorized according to whether the levels were low, normal, or high, based on our institution’s laboratory reference ranges.
The following information was also abstracted from the medical record: date of birth, gender, date of ED admittance, the date of last follow-up or correspondence, and the date of death. In addition, follow-up was updated at the time of the final data analysis using information from the institutional registration database.
2.5. Data Analysis
The primary outcome variable was mortality at 90 days, as estimated using the Kaplan-Meier method. For patients that died within 90 days, the duration of follow-up was calculated from the date of the ED admittance to the date of death. The duration of follow-up for all remaining patients was censored at the date of last follow-up if within 90 days or at 91 days. Serum laboratory measurements were considered as potential predictors of early mortality and the categories were evaluated using indicator variables in Cox proportional hazards models, with and without adjusting for gender and age. The associations were summarized by calculating risk ratios (RR) and 95% confidence intervals (CI). All calculated values were two-sided and values less than 0.05 were considered statistically significant. Statistical analyses were performed using the SAS software package (SAS Institute, INC; Cary, North Carolina).
A total of 97 patients died within 90 days. The estimated mortality rate (± standard error) at 90 days was 19.4% ± 1.8%. Of the 97 deaths, 34 were within 7 days, 36 were within 8–30 days, and the remaining 27 were within 31–90 days of the ED visit. The survival within the first 90 days was not significantly different between females and males (21.9% versus 17.3%; RR 1.3; 95% CI 0.9–1.9; ). The risk of death within 90 days increased twofold (RR 1.9; 95% CI 1.5–2.4; ) for every increase of 10 years in age.
Based on univariate analyses, the presence of each of the elevated white blood cell count, low bicarbonate, low calcium, low hemoglobin, and high glucose as significantly ( ) associated with mortality within 90 days (Table 1). Similar results were obtained for nearly all of these measures after adjusting for age and gender, with the exception that low hemoglobin was no longer significantly associated with early mortality (Figure 1). Since calcium is not part of the standard electrolyte panel at our institution (only collected in 32.6% of patients), calcium was not considered in the subsequent analyses. Elevated white blood cell count, low bicarbonate, and high glucose were each identified as being jointly associated with early mortality ( ) based on fitting multivariate Cox regression models and selecting variables for entry based on the likelihood ratio test. Figure 2 illustrates the survival during the first 90 days after presentation to the ED, with the patients categorized according to the presence of high white blood cell count, low bicarbonate, and high glucose levels. Although there were only a total of 14 patients with both low bicarbonate and high glucose, 11 of the 14 died within 90 days after presentation to the ED. These patients are depicted in groups A and B in Figure 2.
Table 1 Association between laboratory measures and early mortality in AIS.
Serum laboratory parameters versus 90-day mortality in AIS.
Survival during the first 90 days after presentation to the ED, according to the presence of low bicarbonate, high WBC, and high glucose levels.
The results of our study suggest that amongst the routine labs obtained in the ED evaluation of acute ischemic stroke, an elevated white blood cell count, a low bicarbonate, and a high glucose level are independent predictors of 90-day mortality in the setting of acute ischemic stroke.
The association of leukocytosis has been reported by several investigators. In the Atherosclerosis Risk in Communities (ARIC) Study consisting of 13,555 African-American and White men and women, elevated WBC count was found to be directly associated with increased incidence of coronary heart disease and ischemic stroke. Nadav and colleagues looked at white blood cell count in hospitalized patients and noted it to be an independent risk factor for in-hospital stroke. A subgroup analysis of the Clopidogrel versus Aspirin in Patients at Risk for Ischemic Events (CAPRIE) trial concluded that an increase in leukocyte counts over baseline levels predicts a period of increased risk lasting about one week. This risk was independent of cigarette smoking, one of the factors known to confound elevated WBC and stroke associations.
The significance of leukocytosis may have to do with the underlying health status of the patient (patients who are sicker to start would be expected to do worse) or may reflect the degree of inflammation triggered by the stroke itself. Another etiology may be that of a stress reaction; however, no association with glucose was noted in our study (one would expect to see hyperglycemia in the face of a stress reaction). Although several studies as noted above have shown the association, the exact underlying mechanisms by which leukocyte counts are linked to ischemic risk are unknown at the present time.
While diabetes is a known risk factor for stroke, hyperglycemia itself appears to be a risk factor for poor prognosis for stroke as well. Gray et al. note an admission glucose of >145 mg/dL to be significantly associated with worse mortality at 4 weeks. Weir et al. found hyperglycemia to be predictive of poorer functional outcome at 3 months (alive at home versus in care or dead). Animal models have sought to investigate this association of hyperglycemia with poor stroke outcome further. Experimental hyperglycemia has been induced in cats and shown to increase infarct size . Insulin has been administered in an effort to control poststroke hyperglycemia and shown to decrease spatial learning deficit in rats . So far, most of the human studies have focused on retrospective associations of elevated glucose levels (regardless of diabetes) with outcome variables such as death at various time points , assessments of functional outcome using Barthel Index and Rankin scales, and placement following hospital discharge (home versus skilled nursing facility). Only recently have trials have begun to assess the logical next step—whether controlling the hyperglycemia in acute ischemic stroke improves outcome .
The exact mechanism by which hyperglycemia exacerbates acute ischemic stroke outcome is debated. Several theories are postulated, including contribution to vasogenic edema, reduced cerebral blood flow, and increased lactic acid production. Studies have also implicated hyperglycemia in the hemorrhagic transformation of the ischemic infarct . From animal studies, it appears that the most consistent finding is the resulting acidosis produced by hyperglycemia . The next section discusses the possibility of acidosis in acute brain ischemia.
From the pathophysiology standpoint, the accumulation of lactic acid in the brain milieu can be explained by the ischemic brain’s dependence on anaerobic metabolism, which in turn generates lactic acid. Lactate is released as a product of anaerobic metabolism and as such is a nonspecific marker. Saunders et al. demonstrated its presence by short-echo proton spectroscopy in the infarcted brain milieu shortly after focal brain ischemia in humans, and a subsequent fall in lactate levels after the acute infarct had resolved. Markedly elevated cerebral lactate production was also noted in a small cohort of patients with CT proven cerebral infarction following head injury .
An interesting extension of this finding of the presence of lactate immediately after acute ischemic stroke is the concept of correcting such a detectable laboratory abnormality. Correction of acidosis in acute stroke was examined by Kuyama and colleagues . They infused an alkalinizing agent, tris(hydroxymethyl) aminomethane, into the perifocal and systemic circulation of cats in whom left MCA occlusion was experimentally achieved. The alkalinization had the effect of reducing cortical edema and infarct size. A similar study was carried out in the rabbit model , where again infarct volume was decreased by pretreatment with sodium bicarbonate.
These studies suggest that serum alkalinization may be worthy of investigation as therapy in patients with acute ischemic stroke and low bicarbonate levels. This can be done relatively easily with exogenous bicarbonate, either by the oral or intravenous routes. In terms of safety and feasibility in humans, such therapy is already employed in cases of TCA overdose, bicarbonate responsive acidosis, and severe DKA and as part of chemotherapeutic regimens in human subjects.
Calcium is an important electrolyte for multiple physiologic processes. For example, it is needed for clotting factors to work, neural transmission, and bone health. Hypocalcemia, which can be caused by PTH or vitamin D deficiency or resistance, dietary deficiency, renal failure, liver failure, and use of certain diuretics (many of these commonplace in the elderly) can result in tetany, seizures, hemorrhagic transformations of infarcts, and osteoporosis. Osteoporosis is a major contributor to falls, hip fractures, and death in the elderly . Hypocalcemia is also known to cause QTc prolongation , leading to arrhythmias that may increase severity of stroke. Furthermore, serum hypoglycemia may be reflective of the massive influx of calcium into ischemic penumbra in the brain, which triggers the ischemic cascade to produce free radicals and result in brain infarct. Exactly which of these factors related to hypocalcemia is associated with increased mortality in our study is difficult to speculate on, since only information on mortality, rather than immediate proximal cause of death, was obtained.
There are several important limitations to this study. First, since it was observational in nature, not all patients had all the same labs drawn, especially parameters such as calcium. Second, the initial ED laboratory values may be reflective of the patient’s underlying disease, rather than the severity of the stroke itself. Third, patients in our analysis were not stratified by stroke subtype, which again may have confounded the results of the association of labs with mortality. Finally, the parameters noted may simply be independent predictors of mortality, irrespective of any association with acute brain ischemia.
Despite these multiple possible confounders, the previous parameters which are part of routine ED evaluation of the patient with acute ischemic stroke were associated with an increased risk of death at 90 days.
These preliminary results could be further investigated prospectively to see if they can be used as part of a model to predict stroke outcome. Furthermore, the question remains whether correction or manipulation of these observed parameters would result in improved survival.
The results of our study suggest that amongst the routine labs obtained in the emergency department in the evaluation of acute ischemic stroke, an elevated white blood cell count, a low serum bicarbonate, and a high glucose level are independent predictors of 90-day mortality. Low serum calcium also appears to be associated with worse mortality, although our study design did not permit us to evaluate this result in the multivariate model with the others.
Is there an early warning test for stroke?
Strokes seem to come out of the blue. But most of them happen due to decades-long damage to blood vessels and growth of artery-clogging plaque. That raises the question: Is there an early warning test for stroke?
Yes and no. A test called the carotid ultrasound can detect the buildup of cholesterol-filled plaque in the carotid arteries in the neck. These arteries deliver blood to the brain. The test, which uses sound waves, is quick, safe, and without any immediate potential for harm. It makes perfect sense for someone experiencing lightheadedness, memory loss, or the warning signs of a stroke or mini-stroke.
Having a carotid ultrasound test also makes sense for anyone in whom a doctor hears an abnormal sound called a bruit (BREW-ee) as he or she listens to the carotid arteries through a stethoscope. The scan is also a reasonable idea when a person has known risk factors for stroke, such as a previous “mini-stroke,” high blood pressure, high cholesterol, or diabetes. But a carotid ultrasound isn’t a good idea for otherwise healthy people at average risk for stroke.
The U.S. Preventive Services Task Force discourages routine ultrasounds of the carotid arteries. Only about 1% of the general population has significant narrowing of these arteries. And less than 10% of first-time strokes are associated with such narrowings. In addition, roughly eight in every 100 ultrasounds produce a false positive — a result that indicates the presence of significant narrowing that isn’t really there. False positives lead to unnecessary tests and possibly unnecessary treatment.
If you’re wondering whether you should ask your doctor for such a test, or whether to have one as part of a community check-up at a church or community center, here are some questions you might want to consider:
- If the test finds something, what’s next?
- If it doesn’t, are you in the clear?
For most people, a better approach would be to pay attention to fighting things that cause or contribute to the formation and growth of cholesterol-filled plaque — high blood pressure, high cholesterol, obesity, diabetes, not enough exercise, smoking, and the like. Getting those risk factors under control will go a long way to preventing stroke.
For more information on ways to prevent and treat strokes, buy Stroke, a Special Health Report from Harvard Medical School.
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Three new blood tests can help identify hidden risk for a heart attack or stroke in seemingly healthy patients—before symptoms strike. The new tests, now available through Cleveland HeartLab (CHL), check levels of certain biomarkers that have been linked to cardiovascular danger in peer-reviewed studies.
Cardiovascular disease (CVD) is the leading killer of men and women, accounting for one in three U.S. deaths. In 2016, it claimed the lives of 2,200 Americans a day—one every 40 seconds, according to the American Heart Association (AHA).
“What’s especially tragic about these statistics is that heart attacks and strokes are potentially preventable,” says Amy Doneen, DNP, ARNP, medical director of the Heart Attack & Stroke Prevention Center in Spokane, Washington. “The key to saving lives—and hearts—is to identify which patients are at risk and develop a personalized prevention plan.”
Half of Heart Attacks and Strokes Occur in People with Normal Cholesterol
Traditionally, medical providers have checked patients for certain standard risk factors, such as high blood pressure, high cholesterol, and a family history of CVD. However, many heart attacks and strokes occur in people who lack these factors. For example, the AHA reports that about 50 percent of these events strike people with “normal” cholesterol levels.
For a more comprehensive assessment of cardiovascular health, Dr. Doneen now offers the new tests, which she uses in conjunction with inflammation testing and other CVD screening methods in her practice. “The new tests help us further fine-tune risk assessment and prevention strategies for our patients.”
Here is a closer look at the three blood tests–and why Dr. Doneen recommends them to her patients.
1. ADMA/SDMA biomarker test.
What it checks: Now available through Cleveland HeartLab (CHL) this blood test measures levels of symmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA).
Potential benefits: “As recently reported, elevated levels of ADMA/SDMA can indicate damage to the endothelium (the inner lining of blood vessels) and are also an independent predictor of heart attack risk,” says Dr. Doneen. When the endothelium is damaged, LDL (bad) cholesterol particles can invade the artery wall and clump into plaque, which could lead to a heart attack or stroke. Endothelial damage also raises risk for kidney failure.
The ADMA/SDMA test may reveal the underlying cause of high blood pressure and vascular inflammation. As a groundbreaking 2002 study demonstrated, high levels of ADMA/SMDA can be an early warning sign of insulin resistance, the root cause of both type 2 diabetes and about 70 percent of heart attacks, adds Dr. Doneen. The test may also identify people with pre-diabetes/undiagnosed diabetes, reduced kidney function, and early signs of CVD.
2. TMAO biomarker test.
What it checks: This test measures levels of trimethylamine-N-oxide (TMAO), a gut bacteria byproduct that contributes to heart disease risk. The liver produces TMAO after intestinal microbes digest certain nutrients in animal-derived food, such as L-carnitine (found in red meat) and lecithin (found in egg yolks, meats and full-fat dairy products).
Potential benefits: Elevated levels of TMAO predict future danger for heart attack, stroke, and early death in people not otherwise identified by traditional risk factors, according to Cleveland Clinic research published in the New England Journal of Medicine and Nature Medicine. In the studies, those with the highest TMAO levels had a 2.5 times higher risk for a cardiovascular event (such as a heart attack or stroke) over the next three years, compared to those with the lowest levels.
The researchers demonstrated that TMAO directly contributes to cholesterol buildup in the arteries, a discovery hailed by the American Heart Association as one of the top 10 advances in heart disease and stroke science in 2013. “These findings are exciting because they offer new insight into why eating meat and full-fat dairy foods triggers inflammation and arterial disease in some people,” says Dr. Doneen. An important benefit of the new TMAO test is that it can help medical providers individualize their dietary recommendations for patients.
What it checks: The OmegaCheck™ test measures the balance of omega-3 and omega-6 fatty acids in your blood. Omega-3 fatty acids are primarily obtained from food, such as oily fish, and have antioxidant and anti-inflammatory effects. They can also help reduce triglyceride levels. Omega-6 fatty acids are found mainly in animal-based foods and plant oils, and at high levels, contribute to inflammation and blood clots.
Potential benefits: It’s also important to know your ratio of omega-6 to omega-3, says Dr. Doneen. The typical American diet has a ratio of about 10:1, while a diet with a ratio of 4:1 or less may reduce risk for death from CVD or other causes by up to 70 percent over a two-year period, a study published in Lancet suggests.
Low levels of omega-3 fatty acids in the blood are linked to increased risk for CVD, high blood pressure, and elevated triglycerides, while consuming omega-3 fatty acids in food or supplement form helps reduce risk for major cardiac events (such as a heart attack or stroke) in both healthy people and those with CVD risk factors or the disease itself.
As we recently reported, a 2015 meta-analysis of data from 70 randomized clinical trials found that the omega-3 fatty acids EPA and DHA lower blood pressure as effectively as such lifestyle changes as increasing exercise, cutting down on salt, or limiting alcohol. The research was published in the American Journal of Hypertension.
How is a stroke diagnosed and evaluated?
The first step in assessing a stroke patient is to determine whether the patient is experiencing an ischemic or hemorrhagic stroke so that the correct treatment can begin. A CT scan or MRI of the head is typically the first test performed.
- Computed tomography (CT) of the head: CT scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. Physicians use CT of the head to detect a stroke from a blood clot or bleeding within the brain. To improve the detection and characterization of stroke, CT angiography (CTA) may be performed. In CTA, a contrast material may be injected intravenously and images are obtained of the cerebral blood vessels. Images that detect blood flow, called CT perfusion (CTP), may be obtained at the same time. The combination of CT, CTA and CTP can help physicians decide on the best therapy for a patient experiencing a stroke.
- MRI of the head: MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, bone and virtually all other internal body structures. MR is also used to image the cerebral vessels, a procedure called MR angiography (MRA). Images of blood flow are produced with a procedure called MR perfusion (MRP). Physicians use MRI of the head to assess brain damage from a stroke.
To help determine the type, location, and cause of a stroke and to rule out other disorders, physicians may use:
- Blood tests.
- Electrocardiogram (ECG, EKG): An electrocardiogram, which checks the hearts’ electrical activity, can help determine whether heart problems caused the stroke.
- Carotid ultrasound/Doppler ultrasound: Ultrasound imaging involves exposing part of the body to high-frequency sound waves to produce pictures of the inside of the body. Physicians use a special ultrasound technique called Doppler ultrasound to check for narrowing and blockages in the body’s two carotid arteries, which are located on each side of the neck and carry blood from the heart to the brain. Doppler ultrasound produces detailed pictures of these blood vessels and information on blood flow.
- Cerebral angiography. Angiography is a medical test that is performed with one of three imaging technologies—x-rays, CT or MRI, and in some cases a contrast material, to produce pictures of major blood vessels in the brain. Cerebral angiography helps physicians detect or confirm abnormalities such as a blood clot or narrowing of the arteries.
Stroke patients not getting vital test to see if they can swallow, study finds
One in five patients who have the most common type of stroke don’t get recommended screenings to see if the episode damaged their ability to swallow, a recent study in Canada suggests.
Under widely endorsed treatment guidelines, stroke patients are supposed to be screened for what’s known as dysphagia, or an inability to swallow, before they receive any food or drink.
Stroke patients with dysphagia have a higher risk of pneumonia, dehydration, disability and death than people who don’t have difficulty swallowing, previous research has shown.
For the current study, researchers examined data on 6,677 patients hospitalized with ischemic stroke, which results from an obstruction in a blood vessel supplying the brain.
None of the patients were getting support like feeding or breathing tubes that would make them ineligible for dysphagia screening.Stroke patients with dysphagia have a higher risk of pneumonia, dehydration, disability and death. (Getty Images/Cultura RF)
Within 72 hours of arriving at the hospital, 1,280 patients, or about 19 per cent, didn’t get screened, researchers report in Stroke.
Omission of screening mainly occurs in patients with mild strokes, who are only half as likely as patients with more severe strokes to receive screening, said lead study author Dr. Raed Joundi, a neurology researcher at the University of Toronto.
Test needed even in people with mild stroke
Failing a dysphagia screening test increases the risk of poor outcomes — including death, disability, complications — as much as other major prognostic factors like older age and severe stroke, and is true even in people with mild strokes, Joundi said by email.
Elderly people who were at least 80 years old were 44 per cent more likely to get checked for dysphagia than patients under 60. People admitted to the intensive care unit were 56 per cent more likely to receive screening, and patients on a stroke unit had more than double the likelihood compared to those on a regular ward.
Among the 5,144 patients who had a documented dysphagia screening in their medical records, nearly half failed the test. After a severe stroke, 83 per cent of patients failed dysphagia screening, compared with 63 per cent of patients who had moderate stroke and 33 per cent with mild stroke.
Individuals who failed the screening tended to be older and have more chronic medical issues including dementia prior to the stroke.
When they failed the tests, patients were more than four times as likely to develop pneumonia. They also had more than five times the odds of severe disability and were more than twice as likely to be sent to a nursing home or rehabilitation facility after they left the hospital.
Screening efforts need improvement
One limitation of the study is that medical records might have failed to document screenings done for some patients or any tests done outside the 72-hour window examined, the authors note.
Still, it’s likely the results would be similar for patients outside of Canada and for people who have less common hemorrhagic stroke, which occurs when a weakened blood vessel ruptures, Joundi said.
And the findings suggest that screening efforts need improvement, said Dr. Daniel Lackland, a neurology researcher at the Medical University of South Carolina in Charleston who wasn’t involved in the study.
Patients and families should ask about screening, and they should alert doctors immediately to symptoms of dysphagia like difficulty starting to swallow, coughing or gagging while swallowing, drooling, weak voice, lost gag reflex or what’s known as aspiration — food or drink getting into the lungs, Lackland advised.