What blood tests are used to diagnose PVD?
There is no blood test that can diagnose PAD on its own. If you are being evaluated for PAD, your doctor may order blood tests to obtain general information about your health and clues to what may be causing your symptoms. Some blood tests can also help determine your risk of future artery problems. The following is a list of blood tests that may be performed as part of your PAD diagnosis and risk evaluation. Most of these tests can be done with a simple blood sample, drawn in just a few seconds from a vein in your arm. Some kidney function tests require a urine sample.
- Complete Blood Count (CBC)
- Serum Electrolytes
- Kidney Function Tests
- Lipid Panel
- Blood Sugar Tests
- Blood Clotting Tests
- C-Reactive Protein
If you are being evaluated for blood clots in the deep veins of the legs (deep vein thrombosis, or DVT) or chronic vein disease, your doctor will order the general tests listed above (with the exception of CRP).
In addition, a special blood test called the D-dimer test may also be performed, which can quickly rule out a DVT or pulmonary embolism and determine if you need any additional tests.
- D-dimer test
Complete Blood Count
This test measures the overall health of your blood, including the quality and number of red blood cells, white blood cells, hemoglobin (the oxygen carrier), platelets, and other factors. A CBC test can diagnose infection, anemia, blood clotting problems, and other imbalances in the bloodstream that may be contributing to your symptoms.
This test measures the amount of different electrolytes (molecules that carry an electric charge) in your blood, including sodium, potassium, chloride, and bicarbonate. Abnormal levels of electrolytes can be caused by kidney problems, heart failure, or other conditions.
Kidney Function Tests
These tests are performed in all women who are being evaluated for PAD. They are particularly useful in women being evaluated for kidney artery disease to see if limited blood flow is damaging your kidneys or affecting kidney function.
A BUN (Blood Urea Nitrogen) test is used to determine how well your kidneys are working by measuring the amount of urea nitrogen in the blood. Blood urea nitrogen is a waste product that is filtered out of the blood by the kidneys. High levels of BUN indicate the kidneys are not working properly. A BUN level of more than 21 mg/dL is considered elevated, although the exact cutoff varies between laboratories.
A serum creatinine test measures the amount of creatinine in the blood, another waste product that is filtered out of the blood by the kidneys. High levels of creatinine in the blood may be a sign of kidney problems resulting in fluid buildup. A normal value for women ranges from 0.5 to 1.1 mg/dL (milligrams per deciliter) or 44 to 97 µmol/L (micromoles per liter).
Urinalysis (analysis of a urine sample) examines how well your kidneys are working by measuring any physical or chemical changes in urine, such as color, clarity, and the presence of certain compounds. Your kidneys filter your blood and get rid of the waste and extra water as urine, so urine from normal kidneys should not include protein, sugar, blood cells, or bacteria. Poor kidney function may be caused by a lack of blood supply to the kidneys caused by PAD.
High cholesterol is an important risk factor for PAD. A Lipid Panel measures the fatty substances (lipids) in your blood, including your total cholesterol, LDL (bad) cholesterol, HDL (good) cholesterol, and triglyceride levels.
Excess cholesterol that circulates in the blood can stick to the walls of arteries. Over time, this fatty plaque buildup narrows the arteries, causing PAD and other forms of artery disease.
To learn more, see High Cholesterol & PAD Risk and What do my cholesterol numbers mean?
Blood Sugar Tests
A glucose (blood sugar) test measures the amount of sugar in your blood. High levels can indicate that you have diabetes or pre- diabetes, conditions that increase your risk of developing PAD and blood clots in the veins (DVT).
Several different tests can be used to measure your blood sugar: the Fasting Blood Glucose Test measures your blood sugar at a specific time, while the Hemoglobin A1C test measures your average blood sugar levels over the last 3 months.
To learn more about the link between diabetes and PAD and what your blood sugar numbers mean, see Diabetes & PAD Risk.
To learn more about the link between diabetes and blood clots in the veins, see Diabetes & DVT Risk.
Blood Clotting Tests
Blood clotting tests measure how quickly your blood clots. If your blood clots too quickly, a blood clot in your arteries or veins may be causing your symptoms. If your blood clots too slowly, it may indicate bleeding problems. Blood clotting tests also help doctors to determine and adjust the doses of blood-thinning drugs used to treat and prevent blood clots in the arteries and veins. See Aspirin & Blood Thinners for PVD (coming soon) for more.
You may also have tests to look for specific inherited blood clotting problems that can put you at risk for blood clots in the veins. See our article on Blood Clotting Problems & Vein Disease Risk to learn more.
C-reactive protein (CRP) is a substance produced by the body in response to inflammation—the process by which the body responds to injury. Physicians now believe that atherosclerosis, the buildup of fatty plaque on the walls of the arteries that can cause PAD and other forms of artery disease, is an inflammatory process. Women with a high CRP level have a higher-than-normal risk of developing PAD.
See our article on C-Reactive Protein & PAD Risk for more on the link between CRP and artery disease, and to learn what your CRP numbers mean.
High blood levels of this amino acid can damage the linings of the blood vessels and make the blood more likely to form clots. Women with high homocysteine levels in the blood are at increased risk for developing PAD and blood clots in the veins (DVT).
To learn more about the link between homocysteine levels and PAD, and what your homocysteine numbers mean, see Homocysteine & PAD Risk.
To learn more about the link between homocysteine levels and blood clots in the veins, see Homocysteine & Vein Disease Risk.
The D-dimer test measures the levels of a protein that is produced when blood clots are broken down by the body. It is often the first test performed in women with a suspected DVT or pulmonary embolism. The D-dimer test allows doctors to rule out blood clots as a cause of symptoms with 97% accuracy, avoiding unnecessary testing.
A D-dimer test may also be performed after a duplex ultrasound did not find evidence of DVT to make sure blood clots are not the cause of symptoms. If the ultrasound did not identify a clot and the D-dimer test is negative, you do not have a DVT. If the D-dimer test is positive, you will need additional imaging tests (such as a second ultrasound or venography) to look for blood clots the first ultrasound may have missed.
A negative D-dimer test is good assurance that you do not have a DVT or pulmonary embolism and do not require treatment for these conditions. However, a positive D-dimer test is not enough to diagnose blood clots, and further tests will be needed. Elevated D-dimer levels may be caused by many other conditions that damage the blood vessels, and a positive test does not provide any information about the cause or location of a clot.
The D-dimer test is less useful at ruling out DVT in women who have other conditions that elevate D-dimer levels, such as a recent injury or surgery. These women are likely to have a positive D-dimer test even if they do not have blood clots, and should proceed directly to a duplex ultrasound test to look for clots. The D-dimer test is also unreliable in women who have been treated with the blood-thinner heparin, because the test may be negative even if blood clots are present.
D-dimer levels are naturally elevated during pregnancy because a woman’s blood becomes more likely to form clots to prevent excessive bleeding during delivery. Because of this, the standard D-dimer test is not as accurate in pregnant women because it is usually positive even if there are no blood clots. However, some studies have found that specialized versions of the D-dimer test can be useful to rule out DVT in pregnant women.
There is no universally-accepted cutoff for D-dimer levels, and whether your test is evaluated as positive or negative depends on the method used to examine the blood sample.