A thumbnail exhibiting prominent ridges

Other lesser conditions such as brittle nails (bacteria, thyroid, hormonal imbalances), pitted nails (insufficient zinc in the diet or psoriasis), and ridges (inflammatory arthritis or iron deficiency) should also be watched for all are early health warnings.
 
The body also signals problems in many other ways, that's why the ancient physicians and today's holistic medicine practitioners often check the eyes, tongue, and inner ears, some even take hair samples.

Yet, in the end, it's you the patient who's most responsible for your good health and maintaining it. Periodically checking your nails for early warnings of encroaching illnesses is another way to take charge of your body.