D-dimer
Having high levels of the clot-dissolving substance D dimer in your blood may suggest an increased likelihood of blood clots, although D-dimer levels may be elevated by other factors, including recent surgery. Drawing the blood takes just a few minutes, and the risks — which include slight bleeding or a small accumulation of blood at the puncture site — are minor.
The results are available in less than an hour. Normal test results are actually much more meaningful than abnormal ones. That's because many conditions other than blood clots can cause elevated D-dimer levels, while a normal D dimer result essentially rules out the possibility of blood clots.
hs-CRP
How it is used. There are two different tests for CRP. The standard test measures a much wider range of CRP levels but is less sensitive in the lower ranges. The hs-CRP test can more accurately detect lower concentrations of the protein (it is more sensitive), which makes it more useful than the CRP test in predicting a healthy person's risk for cardiovascular disease. hs-CRP is promoted by some as a test for determining the potential risk level for cardiovascular disease, heart attacks, and strokes. The current thinking is that hs-CRP can play a role in the evaluation process before one encounters one of these health problems. More clinical trials that involve measuring hs-CRP levels are currently underway in an effort to better understand its role in cardiovascular events and may eventually lead to guidelines on its use in screening and treatment decisions.
When it is ordered. hs-CRP usually is ordered as one of several tests in a cardiovascular risk profile, often along with tests for cholesterol and triglycerides. Some experts say that the best way to predict risk is to combine a good marker for inflammation, like hs-CRP, along with the lipid profile.
Homocysteine
Homocysteine is commonly used as a screen for people at high risk for heart attack or stroke. It may be useful in patients who have a family history of coronary artery disease but no other known risk factors. However, its utility for this purpose continues to be questioned because the role, if any, that homocysteine plays in the progression of cardiovascular disease (CVD) has not been established. Routine screening, such as that done for total cholesterol, is not yet recommended.
LDL-D
Measurements of low density lipoprotein cholesterol (LDL-D) are helpful in assessing a patients risk for heart disease and in following therapy to lower cholesterol. A standard lipid profile consists of total cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglycerides. By applying a formula, the amount of cholesterol present in low-density lipoprotein can be determined, and this calculated value is typically reported as well. When triglycerides are high, the formula no longer applies. In this situation, the only way to accurately determine LDL-D is to measure it directly.
Other Test Definitions
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