Blood Tests Made Simple

In Your 40s:  
Keep up your cholesterol, triglyceride, blood sugar, and HIV checks; get a thyroid function test or recheck if you have symptoms or your doctor recommends it.

C-reactive protein: Check after age 40 if you're at "intermediate" risk for a heart attack or stroke—you have slightly high cholesterol, a large waistline, a family history of heart disease, or are a little overweight. "This can be the tie-breaker in helping your doctor decide whether you should start a statin drug," says cardiologist Erin Michos, MD, assistant professor of medicine at John's Hopkins School of Medicine. Be sure you're getting a high-sensitivity CRP test. 
The healthy target: 2 milligrams per liter or lower.

In Your 50s and Beyond:
Continue with thyroid, cholesterol, blood sugar, and HIV tests; a CRP check is advisable for all women over 60.

Vitamin D: "Three-quarters of women are deficient in D," Pregler notes, and this can leave their bones at risk. "For most of us, it's smart to consider taking 1,000 to 2,000 international units of supplemental D daily." Have your levels checked if you're younger than 65 and are at risk for osteoporosis—or if you're 65 or older—along with your routine bone-density check. Though chronically low D levels in women have been loosely linked to breast cancer and other conditions, experts aren't ready to advise earlier testing.
The healthy target: 30 to 74 nanograms per milliliter or higher. 

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