Calcium under fingernails?!?

I know everyone has them, but I was wondering why exactly there is calcium in your fingernails. I thought calcium was in your bones! Fingernails are cartilage are they? Not bones! Also, I was wondering why they are so randomly placed. Does it have anything to do with wearing nail polish a lot? Because I always have nail polish on, but now I don't have it on and there's a few of those little white calcium dots.

From Andrew Weil, MD:

"The spots you notice are not caused by a calcium deficiency. They're called "leukonychia" and are very common. Most of the time the white spots simply are a sign of some past injury to the matrix (base) of your nails. By the time the white spot shows up (about six weeks after the injury) you've probably forgotten all about banging or knocking your fingers. Sometimes, the injury can stem from a manicure that put excessive pressure on the base of the nails. The spots also can be a sign of an allergic reaction to nail polish or nail hardeners and, sometimes, are a symptom of a mild infection.

Whatever the cause, the spots are temporary and will grow out as your nails grow. However, it can take more than eight months for nails to grow out completely so the spots may be around for a while.

Sometimes, a change in the appearance of your nails does indicate an underlying disease, but these changes would be more dramatic than just the occasional white spot. Nails that turn completely white, for example, can indicate liver disease, but by the time this happens, you probably would have other symptoms.

Incidentally, in addition to the myth that white spots on the nails are a sign of calcium deficiency, you may also have heard that they indicate a zinc deficiency. That isn't true either. Neither is the well known but bizarre notion that the spots are due to eating too much Hellmann's mayonnaise (I'm not making this up)."

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From Sound Medicine, Indiana School of Medicine:

"It's a common medical myth that white spots on your fingernails are caused by too little calcium in your diet. However, these white spots (called leukonychia) are not a sign of a calcium deficiency. But they can be an indicator of other problems.

The most common cause of leukonychia is blunt trauma to the nail bed, such as a knock or a blow. Due to the slow growth rate of nails, the white spots of leukonychia may appear gradually and linger for months.

Other causes could include a rough manicure, a slight allergic reaction to enamels or other nail products, or even a mild bacterial or fungal infection.

White spots can also appear on toenails, but regardless of their location, they are generally harmless and will disappear with time. However, a nail that turns completely white could be a symptom of liver disease and should be looked at by a doctor."

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