What blood test do you really need? And how often should you do them?
By Laura Entis
Sometimes it can seem like almost every doctor visit you make is that they draw blood. Blood tests can provide a lot of information about your health. But whether you should get a specific test (and how often) depends on your health and medical history; In this case, more is not always better.
Here’s everything you need to know about 3 blood tests that everyone should have and 3 others that might be a good idea to consider.
A complete blood count
A complete blood count (CBC) measures red and white blood cells, as well as platelets. It can help identify infections, conditions such as anemia and even blood cancer.
The test “also looks at kidney and liver function, thyroid function, and electrolytes such as potassium, sodium, and calcium,” says Stephen Kopecky, MD, a cardiologist at the Mayo Clinic in Rochester, Minnesota.
How often should you get one? It depends. If you’re in good health, “every 2 or 3 years is fine,” Kopecky says. But if you have a condition like kidney disease that needs to be monitored more closely or if you are taking certain medications, including some prescription drugs for high blood pressure or cholesterol, “The test should be done annually.”
A metabolic panel
A basic metabolic panel is used to evaluate glucose levels and can detect diabetes and prediabetes, as well as analyze lung and kidney function. A comprehensive metabolic panel includes all of the above, plus 6 different tests to examine liver function. Both measure electrolytes and typically require fasting.
How often should you get one? The US Preventive Services Task Force recommends every 3 years for adults who are overweight or obese but have normal glucose levels. Other experts recommend that same period of time for all people over 45 years of age.
Lipid panel
The lipid profile, which may often require prior fasting, measures cholesterol and triglyceride levels. High or borderline results may indicate an increased risk of heart disease.
How often should you get one? Every year for people over 65, according to the National Institutes of Health.
A1C
A hemoglobin A1C test measures your average blood sugar (glucose) levels over the past three months and can be a useful tool in diagnosing diabetes and prediabetes. It doesn’t require fasting, Kopecky says. But it’s often not covered by Medicare, says Matthew Weissman, MD, chair of the department of medicine at Mount Sinai Beth Israel Hospital and Mount Sinai Downtown.
Who should have this test? The Centers for Disease Control and Prevention recommends that everyone over age 45 get at least one A1C test for reference. If your result is normal but you have risk factors such as being overweight, the agency recommends repeating the test every 3 years.
TSH
A TSH (thyroid-stimulating hormone) test can detect thyroid gland dysfunction, whether it’s overactivity (hyperthyroidism) or underactivity (hypothyroidism), says C. Noel Bairey Merz, MD, director of the Barbra Streisand Women’s Heart Center. at Cedars-Sinai in Los Angeles. Although it can be treated and is rarely life-threatening, a thyroid imbalance “affects virtually every organ group,” says Bairey Merz, which can cause a wide variety of symptoms, including weight changes and sleep problems. .
Who should get tested? If you have a family history of thyroid disease, Weissman recommends getting tested every few years. If you have no history and no symptoms, the evidence for regular screening is insufficient. “For many older adults, getting this screening is a reasonable step,” says Bairey Merz.
Vitamin D
Vitamin D testing is somewhat controversial. Those in favor, including Kopecky, say it can be useful in detecting a common deficiency. However, critics, including Bairey Merz, point out that randomized clinical studies have raised questions about the health benefits of taking vitamin D supplements.
Who should get tested? At Weissman’s office, they generally recommend testing only for those with osteoporosis, to make sure vitamin D deficiency is not a risk factor. “There is conflicting information about which diseases vitamin D supplements can actually help,” he says.
Editor’s note: This article was also published in the February 2024 issue of Consumer Reports On Health.
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