What can my nails tell me about my health?

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Q: I’ve noticed some odd changes to my nails that weren’t there before. What can our nails tell us about our health? And how can I keep my nails healthy?

A: Our nails are a unique window into our overall health. Many diseases are associated with distinctive nail changes – from the spoon-shaped nails of iron deficiency anemia to the rounded, swollen nails of cystic fibrosis.

In my third year of medical school, I met a patient who had come to the emergency room throwing up blood. After directing the rest of the team to stabilize the patient, the doctor in charge held the patient’s hand and looked closely at their fingernails. They were a frosty white, except for a strip of red at the tips. I’ve never forgotten that appearance (a finding known as “Terry’s nails”), or how the doctor turned to me and said, “I bet this patient has cirrhosis.”

At first I was incredulous – how could she guess the patient had a liver problem of all things just by looking at the fingernails? But she was right: The patient had complications from cirrhosis.

Here are some common nail changes that can tell you something about your health:

Dark vertical streaks: Called splinter hemorrhages, these can result from nail biting but also from an infection of the heart valves.

Horizontal ridges: Known as Beau’s lines, these ridges across the nail occur when nail growth is interrupted by a major illness or chemotherapy. They also have been described by people after getting covid-19.

Pitted, discolored nails: This can be a sign of nail psoriasis, an autoimmune condition.

Brittle nails: Brittle nails happen more often among women and in older age. Wearing protective gloves and reducing contact with dishwater, detergents or nail polish remover can help.

White, yellow or brown nails: This can be a sign of fungal infection, which can often start in the feet at the great toe and spread. In some cases, people make the mistake of using over-the-counter products to treat only the nails, without realizing that the fungus is also on the skin. See a doctor to determine what type of oral or topical treatment is best, and be sure to discuss medications you’re already taking to avoid drug interactions.

Half-and-half nails: Also known as Lindsay’s nail, these changes seen in kidney disease make the bottom half of the nail a milky white and the top half a brownish-pink. Sometimes, these nails return to normal after kidney transplantation.

Tracey Vlahovic, clinical professor in the department of podiatric medicine at Temple University, said that nail changes, like those that occur with psoriatic arthritis, might be an early sign of a systemic issue.

Keep in mind: Nails grow slowly (it takes about six months to regrow a fingernail), so not only could an abnormality reflect an illness that occurred several months prior, but any treatment prescribed to you may take time before you see results.

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Why some common manicure practices can be damaging

Since we’re talking about nails, it’s important to note that while manicures and pedicures may be visually appealing, they’re probably not doing much for the “health” of your nail, and some practices may be damaging.

Take pushing back cuticles, for example. You may have thought that the rather uncomfortable shoving and trimming of the cuticles is a necessary evil and that cuticles serve you no purpose.

Not so. Removing cuticles, in fact, increases the risk of an infection.

“Both your cuticles and the tip of your nail are there to keep the environment outside of the body,” said Vlahovic. “Scraping or pushing those areas back opens doors that should not be opened.”

She recommends only having nails filed and polished, or going to a spa that offers medical pedicures with instruments that have been sterilized with an autoclave device.

Popular gel manicures can lead to thinning of the nail plate and brittle nails due to the repeated application and removal process (often involving soaking with acetone and mechanical peeling). And I know I’m not in alone in having entered a Faustian bargain by wanting to cover damaged nails from a gel manicure with . . . another gel manicure.

Many supplements purporting nail growth contain biotin (and are taken daily by nearly 3 percent of U.S. adults). But according to the American Academy of Dermatology, there is no evidence that biotin promotes nail growth or quality in otherwise healthy people.

And taking biotin isn’t harmless: Biotin can interfere with blood tests such as troponin, used commonly to help diagnose a heart attack, and lead to a false negative result. This could have serious consequences, especially among women for whom heart attacks are already underdiagnosed.

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What I want my patients to know

Nail health is not something you want to self-treat. It’s easy to get the diagnosis wrong because many nail issues look similar. If you’ve noticed changes to the shape, texture or even color of your nails, talk to your provider about whether there’s any cause for concern.

Trisha S. Pasricha is a physician at Massachusetts General Hospital, an instructor in medicine at Harvard Medical School and a medical journalist.