Originally published in The Ottawa Citizen May 11, 2005
Original Title: Forget the Palms, Look at the Nails!

Many diseases can alter the appearance of our fingernails and toenails. Curvature changes, discolourations, lines and pits are clues used to diagnose various conditions.

Nails are made of stacked sheets or layers of protein called keratin. The soft whitish halfmoon area found at the base of the nail is called the lunula. The nail grows from a nail bed or matrix located just under the cuticle adjacent to the lunula. This matrix has two sections: The section closest to the cuticle’s edge (distal matrix) produces the deeper layers, and the section farthest away from the edge (proximal matrix) produce the superficial or top layer of the nail.

Changes in the colour of the lunula can be revealing. In patients with Wilson’s disease, a liver defect that leads to copper overload, the lunula can turn a blue hue (azure lunula). A red lunula can indicate heart failure, and the antibiotic tetracycline, commonly used to treat acne, can turn it yellow. Too much fluoride can turn nails brown or black.

Nails grow about one millimetre every six to 10 days. If the distance between the line and the nail bed is known, it can help the physician estimate when an acute disease began. Various lines running the length or breadth of the nail can appear at times. They can be the result of a bad flu, trauma, cold exposure or more severe disease.

A common benign condition in children and active adults is leukonychia. These are random uneven white lines that can appear on more than one nail. These lines do not span the nail. Minor trauma to the proximal nail bed is thought to be the likely cause and it is of no clinical significance.

Red or brown lines running the length of the nail can be splinter hemorrhages. These occur when the tiny blood vessels (capillaries) in the skin under the nail leak blood. This condition is a classic sign in people with inflammation of the inner lining of the heart (endocarditis). It is also seen in people who have lupus, rheumatoid arthritis, malignancies, trauma, psoriasis, localized fungal infection or peptic ulcer disease, and in women who are pregnant or using the birth control pill.

Yellow-nail syndrome occurs when the nail’s growth slows and it becomes thicker. The edges of the nail curve downward. The lunula disappears and the nail turns yellowish in colour.

People who suffer from chronic lung congestion (bronchiectasis), sinusitis, fluid accumulation around the outside of the lung (pleural effusions), immune system damage or deficiency, poor drainage of fluid away from the extremities (impaired lymphatic drainage) or malignant cancers can develop yellow-nail syndrome. Protein leaking from damaged nail bed capillaries is thought to cause the discolouration.

Ten per cent to 50 per cent of people with psoriasis will develop pitting nails. Psoriasis, allergic reactions or chemical irritation around the nail bed can damage the proximal matrix, causing small pits to form on the nail surface. Connective tissue diseases, pemphigus (a blistering skin disease) and alopecia areata (localized scalp hair loss) are other causes.

Clubbing, although technically not a nail change, occurs when the skin surrounding the cuticle can become thickened and spongy. It is associated with lung diseases like cancer, bronchiectasis, scarring (pulmonary fibrosis), cystic fibrosis and lung abscesses and celiac disease, cirrhosis, inflammatory bowel disease, and in some instances congenital heart disease and endocarditis.

When clubbing is noted without any other symptoms, a thorough investigation for lung cancer is required.

When the nail curves upward and away from the fingertip appearing spoon-shaped (koilonychia), it can be a normal variant in infants that resolves with several years. For older children and adults it can be a sign of iron deficiency, iron overload (hemochromatosis), or due to trauma or constant occupational exposure to petroleum-based solvents.

Unlike palm lines, your nail’s appearance can reveal more about you than you think. Ask your doctor to check them out.