The nails of both your hands and feet are made of keratin, a hardened protein. They serve as a protective tool of the body and also help in various tasks. Healthy nails are smooth, slightly curved with a rounded edge, pinkish in colour, without any ridge, line or bumps. Any change in colour, appearance or shape of nails can indicate any deviation from sound health. Many people, particularly women, like to keep their nails well-manicured and painted.

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But they may be unaware of the importance of nails as an indicator of good health.

In various deficiencies or disease conditions, the shape, colour, texture or smoothness of nails can be altered. The alteration varies in intensity as per severity of the underlying pathological condition. It starts slowly and progresses slowly. Treatment of the condition and reversal of the underlying pathological process can reverse the changes in nails.

Yellow discolouration of nails can be due to fungal infections. People with diabetes or weakened immune systems—such as the elderly, young children, or individuals with HIV or cancer—are more prone to fungal nail infections. In these cases, discolouration is often the only noticeable sign, since nails, unlike skin, do not itch even when infected. In psoriasis, a chronic skin condition marked by whitish, flaky lesions, the nails may also become discoloured and can even separate from the nail bed. Other causes of nail discolouration include anaemia and conditions that lead to poor blood circulation, such as vascular disorders or kidney disease. These can result in a whitish appearance of the nails due to reduced oxygen and nutrient supply.

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The nails can become discoloured, thickened and even deformed due to diabetes. Heart and or lung problems, which cause reduced oxygen saturation of the blood, can cause blueish discolouration of the lips and nails. Swelling around the nails, with obliteration of the space between nails and nail bed, is a sign of chronic obstructive pulmonary disease, in which there is chronic inflammation and obstruction of the lung airways. Dark lines or spots on the nails could be a sign of melanoma or some serious disease. Pale nails indicate, anaemia, liver, kidney or heart diseases.

Chronic kidney disease and kidney failure are often associated with whitish lines on the nails, as well as spoon-shaped, brittle, or easily broken nails that grow slowly and with difficulty. Protein deficiency can also lead to brittle or broken nails, often accompanied by ridges on the nail surface. Similarly, calcium deficiency may cause nails to become fragile and prone to breaking. Frequent exposure to moisture or harsh chemicals is another common cause of brittle or damaged nails. Other factors that may contribute to brittle nails include: Hypothyroidism (underactive thyroid), ageing, vitamin B12 deficiency, and mineral deficiencies, especially zinc. In alopecia areata, a condition that causes patchy hair loss, nails may develop white vertical ridges and small depressions (pitting) on the surface.

Any injury to the nails or nail bed can break them or cause pitting over their surface. It can also cause dark lines or dark discolouration below the nails. As the injury heals, the normal look of the nails is restored. This restoration takes four to eight months in fingernails and 12 to 18 months in toenails. Due to any infection or inflammation, nail folds become red, swollen and painful to touch as well.

It is essential for individuals to be aware of the normal features of healthy nails—including their appearance, texture, shape, and colour. Any noticeable change in these characteristics should raise concern, and one should consult a doctor. Apart from trauma or injury, most nail changes are often linked to chronic nutritional deficiencies.

By clinically correlating nail changes with a patient’s medical history, other physical signs, and the results of laboratory investigations, healthcare professionals can often arrive at an accurate diagnosis. This is helpful in management of the disease or disorder, ultimately contributing to the restoration of health.

Dr Rachna Pande is a specialist in internal medicine.