|Fingernails| are simply another form of skin. They are formed by a hardened |protein| called ~keratin~, which has a high sulphur content. Contrary to popular belief, the calcium content of nails is very low.
Your |fingernails| are one of many indicators of health. Any dramatic changes in their texture, shape, color, or growth rate may be a signal to seek medical advice. Although a careful physician will always look at the nails, diagnosing or predicting any generalized ailment would be impossible on the basis of the nails alone.
