Every disease has its signature symptoms. For example, thyroid disorders (like hyperthyroidism and hypothyroidism) are most often associated with weight loss and weight gain, respectively. However, doctors frequently link up nail changes with thyroid diseases, too.
The presence of onycholysis often occurs with hyperthyroidism [source: Gregoriou, et al]. Also known as Plummer's nail, this condition occurs when a fingernail -- most often the ring finger or little finger -- or a toenail separates itself from the nail bed. This lifting can occur at the tip of the nail or along the sides.
Because dirt and moisture can easily collect under lifted nails, Plummer's nail can easily lead to bacterial and yeast infections. Therefore, it's important to see a doctor as soon as possible if you notice any separation of your nails. Not only will you require tips on preventing infection, you'll also need to seek treatment for the underlying cause of the condition.
Spoon nails, which are nails that are concave and look scooped away from the finger, can be a symptom of hypothyroidism [source: Mayo Clinic].
There are many more surprising conditions the state of your nails can help diagnose. Keep reading to see the rest of our list.