PATTI NEIGHMOND, BYLINE: And I'm Patti Neighmond.
If you're a man and worried about your testosterone levels, endocrinologist Ronald Tamler says you should get a blood test to measure levels first thing in the morning.
DR. RONALD TAMLER: More than other hormones, testosterone goes up and down throughout the course of the day and its highest between 8 and 10 in the morning.
DR. BILL REILLY: If the hormone is measured in the afternoon, results can be misleading. They may be low when in fact they're just low in the afternoon. And you should have the test done twice on different days just to be sure. If it truly is low, there are a number of possible causes.
TAMLER: The most common reason for low testosterone in my practice I find is obesity.
NEIGHMOND: Tamler says that fat tissue, especially abdominal fat, can turn testosterone into the female hormone estradiol.
TAMLER: And that has two affects; the first one is that there's less testosterone.
NEIGHMOND: The second one is that the extra estradiol disrupts signals to the brain, telling it not to produce more testosterone.
In a recent study, Tamler found when obese men had weight loss surgery and lost on average about 40 pounds, their testosterone levels doubled over the course of a year. Diabetes and sleep apnea can also cause low testosterone and should be treated first, he says, before embarking on hormone therapy.
If it turns out testosterone levels are truly low, then doses of the supplement need to be carefully tweaked to make sure it doesn't cause production of too many red blood cells.
TAMLER: The amount of red blood cells in circulation can go up very high, and that can mean that the blood does not flow as smoothly as it should and that can give you troubles. You don't want to have blood that is too thick because it can cause clots.
NEIGHMOND: Leading to heart attack or stroke. Tamler says its important for patients to see a specialist once every six months.
Patti Neighmond, NPR News.
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DAVID GREENE, HOST:
The first piece in our health segment from Sarah Varney came to us from our partner Kaiser Health News, a nonprofit news service.
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