top of page

NAILed It!

Nails can be a window into internal diseases including end organ disease and infections.

Systemic diseases can impact the integrity of the nail matrix, the germinative part of the nail apparatus —likened to the “engine of the car”. This can further impair nail growth and the attachment of the nail plate to the nail bed. Mechanical trauma, chemotherapy, stress on the body (childbirth, major injury) and viral infections (hand-foot-mouth disease) can all lead to temporary stoppage of the nail matrix growth.


The nail bed lying underneath the nail plate is embedded with thin blood vessels running longitudinally. Trauma or blockage to these fine blood vessels can result in splinter hemorrhages (red linear streaks in the nail). In addition to external trauma, psoriasis and onychomycosis (fungal disease of the nail), endocarditis (infection of the heart valves) and vasculitis are internal diseases that can result in splinter hemorrhages.


The “half moon” of the fingernail is called the lunula (latin for “little moon”), which normally abuts the proximal nail fold and appears an opaque. A red lunula may be a cause of concern for various autoimmune conditions, such as lupus, rheumatoid arthritis and dermatomyositis. A bright red lunula can also be seen in the following internal diseases: liver failure/cirrhosis, carbon monoxide poisoning, heart failure and COPD.


The curvature of the nail plate itself, called clubbing, can be a helpful clue for underlying pulmonary disease. To assess for clubbing, hold the two opposing fingers back against each other. A diamond-shaped space (a “window”) should normally appear between the nails of the two fingers. In clubbing, however, this “window” is often absent.

Yellow discoloration of the nails can be due to a various internal and external causes. Occupational and grooming practices are examples of such external causes. Amyloidosis, fungal infection, vitamin deficiencies, congenital diseases, medications, diabetes, as well as, thyroid, liver, kidney and pulmonary disease are examples of internal causes of yellow nail discoloration.

External causes (“outside - in”):


Frequent use of nail polish can lead to a yellow staining of the nail plate. The dye in the nail lacquer interacts with the keratin of the nail plate causing a yellow discoloration and brittleness. Polish remover can further induce nail yellowing by allowing the dissolved nail polish to closely adhere to the nail plate. Some have linked resorcinol as an ingredient in many nail lacquers as the culprit for the pale orange or yellowish-red discoloration of the nail. The