Though small in size, your fingernails can offer important clues that point to larger underlying health problems,­ such as lung disease, diabetes…and even cancer.

Nail changes may be among the first symptoms of an undiagnosed condition. That’s because conditions that affect your entire body often alter blood flow to your nails, leading to changes affecting their color, shape, thickness and texture. Paying attention to these digit-protectors could help you get an early diagnosis. 

Nail changes to watch for…*

Clubbed Nails

Clubbed nails look like upside-down spoons. The fingertips may be swollen underneath. Some people are born with clubbed nails, but clubbing that appears later in life, called acquired clubbing, is almost always health-related.

What it could mean: Eighty percent of people with acquired clubbing have an underlying lung disorder, usually­ lung cancer, chronic obstructive pulmonary disease (COPD) or some other lung disease. This nail condition also can occur in people with an infection of the lining of the heart chambers and heart valves (infectious endocarditis). 

For unknown reasons, these lung and heart conditions can cause the connective tissue near the fingertips to grow abnormally fast, and the nail must change shape to accommodate the bulging tissue underneath. The medical conditions that accompany acquired clubbing usually reduce the amount of oxygen in the blood.

Getting diagnosed: If you notice clubbing (that you weren’t born with) but haven’t been told that you have a lung or heart problem, mention it to your primary care physician.

Your primary care physician should take a full history that includes details of any past or current smoking. He/she should also order a cardiopulmonary workup, including a chest X-ray. Once the underlying cause is treated, the clubbing should disappear.

White Nails

Healthy nails feature an all-pink to beige nail bed with longer nails also having a white tip. However, a condition known as Terry’s Nails occurs when more than two-thirds of the nail—the part closest to the cuticle—appears white, and the remaining band, close to the tip, is pink or red. The lunula (the half-moon shape at the base of the nail) usually disappears. 

What it could mean: Terry’s Nails often accompanies cirrhosis of the liver, diabetes or congestive heart failure. The condition tends to occur on both hands and is often more pronounced in the thumbs and index fingers. 

Getting diagnosed: See your primary care physician, who will conduct a full history and physical.

Dark Streaks

A dark streak in your nail could be harmless—an injury, such as a door slam, can “wake up” pigment-­producing melanocytes in the nail, causing a brown streak to appear. These harmless streaks are common in people with darker skin. Up to 80% of African-American adults can develop these benign pigment bands.

What it could mean: The streak could be subungual (“under the nail”) melanoma, a potentially deadly form of skin cancer resulting from melanocytes below the nail growing in an uncontrolled fashion. Compared with Caucasians, melanoma in African-Americans, Asians and Native Americans is more likely to affect the nails, palms and soles. Nail melanoma usually appears as a single brown or black band running lengthwise along the nail and is most common in the thumb, index finger or big toenail. 

Getting diagnosed: Not every dark streak is a melanoma, but it’s always prudent to show your dermatologist. People tend to dismiss these streaks (or disguise them with polish), so nail melanoma is often diagnosed late. Caught early, it is treatable. A dermatologist will examine it and order a biopsy if needed.  

*Before having your nails examined by a doctor, always remove any nail polish.