High-Sensitivity C-Reactive Protein (hs-CRP) Test
C-reactive protein is a protein particle that is elevated when there is inflammation in the body, whether from a viral infection, a bacterial infection, arthritis, or an injury, including the chronic injury to the arterial walls that is part of the atherosclerotic process. Elevated CRP is also associated with a greater tendency for the blood to clot. This makes plaque rupture more likely to produce a large enough blood clot to block blood flow in an artery and cause a heart attack.
The advanced blood test is called a high-sensitivity C-reactive protein (hs-CRP) test to differentiate it from a basic CRP test. For both men and women, the amount of CRP in the blood is a good overall predictor of the risk of having a heart attack. You are at low risk if the amount of CRP in your blood is 1 mg/L or less, at average risk if the amount is between 1 and 3 mg/L, and at high risk if your level is above 4 mg/L.
An elevated level of CRP is often found in smokers and in patients with central obesity (belly fat) and diabetes. It is also often elevated in patients with chronic periodontal disease. Inflammation is associated not only with heart attack and stroke, but also with other chronic diseases of Western civilization, including cancer, Alzheimer's disease, and macular degeneration.
In order to accurately tell whether a patient's elevated hs-CRP is truly a sign of chronic underlying inflammation, the test should be repeated three times with at least several weeks in between, and only when there are no apparent infections or injuries. Exercise, weight loss, smoking cessation, and statin drugs help to lower hs-CRP.
Follow-up. If the hs-CRP test is normal, the test need not be repeated routinely unless there is a change in risk factors, such as weight, exercise frequency, or smoking status. If it is elevated, I generally repeat the test every few months to monitor its response to favorable lifestyle changes and/or medications.
Homocysteine is a product of protein metabolism and has been found to be a risk factor for heart attack, stroke, and other vascular diseases. Its role as a cardiac risk factor was first brought to light by Harvard researcher Kilmer McCully, MD, in 1969. Dr. McCully had noticed that children with genetically inherited homocystinuria (the inability to metabolize homocysteine and other amino acids normally) developed vascular disease at very young ages. In these children, homocysteine built up to very high levels in the blood until it spilled over into the urine. Dr. McCully reasoned that if extremely high homocysteine levels could cause early vascular disease, perhaps lower levels that were still higher than normal might be a risk factor for heart disease in adults. After years of skepticism, his theory has been borne out.
Whether you are a man or a woman, if you have a homocysteine level of 12 μmol/L, you are at greater risk for a heart attack or stroke. What has not been proven is whether treating high homocysteine levels with a cocktail of B vitamins (which many doctors have been recommending) can prevent heart attack and stroke in high-risk people. My suggestion is to eat plenty of whole fruits and vegetables and other foods that contain B vitamins, but avoid the supplements.
Follow-up. A yearly test for homocysteine is helpful in reassessing risk.
This is a simple blood test that reflects the average level of your blood sugar over the prior 3 months. As such, it gives a more meaningful picture of what is happening with your blood sugar than an isolated blood glucose test. There isn't one number that truly divides normal from abnormal blood sugar. A hemoglobin A1c level of 5.7 percent or higher is borderline, and greater than 7 percent is where we begin to see complications of diabetes. Those who have gained weight in middle age and have a level close to 5.5 percent are at risk of future diabetes if they continue to gain weight.
Follow-up. If a patient's hemoglobin A1c level is borderline or elevated, I repeat the test every 3 to 6 months to monitor the person's improvement — or lack thereof — with diet, other lifestyle changes, and medications. Along with monitoring triglycerides and HDL, following hemoglobin A1c is an excellent way for both the patient and the doctor to monitor the success of their efforts.