Subtle signs of health problems your bikini line forecast your fertility? Yep. And those dark under-eye circles aren't only a hangover giveaway. Learn to ID these and other subtle signals of potentially serious health problems.

You spy: The hair down there starting to grow in a square
What it might mean: If your pubic hair is growing on your thighs and up your belly, forming a more square "rug" shape than a triangular one, you may have polycystic ovary syndrome. Caused by excess male sex hormones, PCOS can spur body-hair growth and disrupt ovulation. "Some women with PCOS don't realize something's wrong until they have trouble conceiving," says Katherine Johnston, M.D., instructor of medicine at Harvard Medical School in Boston.
Your next step: PCOS raises insulin levels and could eventually lead to diabetes and heart disease, so see your doctor to have your hormone levels tested. "I might put patients on a diabetes drug," Dr. Johnston says. "It helps lower insulin, in turn balancing sex hormones and restoring regular ovulation and fertility."

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You spy: Nails that turn white when you press on them
What it might mean: All nails blanch a bit when you apply pressure, but if yours stay white for up to a minute, you may be anemic and low on iron. "Many women, especially those with heavy periods, can become anemic without even knowing it," Dr. Johnston says.
Your next step Have your blood's ferritin levels tested. You may need to eat more iron-rich foods such as salmon and spinach, but don't take an iron supplement without your doc's say-so.

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You spy: Desert-dry lips
What it might mean: It's either time to chug some water or take a closer look at your vitamin A intake. "I had a young woman who didn't know that she was getting 20,000 international units of vitamin A every day-that's four times the recommended daily value and approaching the toxic dose of 25,000 IU-from two different supplements," says Carolyn Jacob, M.D., a dermatologist in Chicago. In healthy amounts, vitamin A is essential to skin-cell turnover, but too-high levels can sap moisture and, if you're pregnant, cause birth defects. "It completely dried out my patient's lips and skin," Dr. Jacob explains.
Your next step: If you take supplements, check the labels to make certain you're not taking in more than 5,000 IU daily; be sure to account for the vitamin A you get from natural sources such as eggs and fortified milk, too. Soon after you stop overdosing, your pucker should plump up again. And regardless, down plenty of water-especially if you work out. Remember, if you feel thirsty, you're already dehydrated.

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You spy: Swollen fingers
What it might mean: Salty snacks and PMS are obvious bloat culprits, but if you shun the shaker, your period isn't due for weeks and still your rings are tight, a sluggish thyroid may be to blame. This condition, called hypothyroidism, occurs when the gland underproduces the thyroid hormones needed to regulate metabolism, heart rate and more, says Rebecca Bahn, M.D., professor of medicine at the Mayo Clinic College of Medicine in Rochester, Minnesota.
Your next step: Don't write off puffiness as inevitable, Dr. Bahn warns. "Untreated hypothyroidism can lead to heart disease, and if you're even slightly hypo and get pregnant, it could affect the baby's brain development." A blood test can reveal if your thyroid isn't producing enough hormones; if so, your M.D. may prescribe synthetic hormone pills, likely for the rest of your life. Once you find the right dose, your metabolism (and fingers) should return to normal.

Yellow eyelid bumps? Discolored finger nails? See the rest of our subtle signs of illness!