If You Notice This With Your Fingernails, Get Your Thyroid Checked

This subtle sign is often overlooked—here's what to look out for.

Hypothyroidism, also known as underactive thyroid, occurs when the thyroid gland becomes unable to produce certain hormones in adequate amounts. The Cleveland Clinic warns that when hypothyroidism is left untreated, these hormones can dip to dangerously low levels. In rare cases, this leads to myxedema—a dangerous condition which can cause anemia, confusion, heart failure, or even a coma. That's why it's so important to recognize the signs of a thyroid problem before it spirals out of control. Experts say that besides the condition's more common symptoms, there's one sign of hypothyroidism you may notice in your fingernails. Read on to find out what to watch for, and how your doctor can help.

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Slow-growing, brittle nails can signal a thyroid problem.

Hand fingernails

An underactive thyroid affects many parts of the body, including your fingernails. "When the thyroid is underactive, the body slows down due to a decrease in thyroid hormones. This causes slow-growing and brittle nails," says Thyroid Symptoms, an informational site run by the pharmaceutical company Viatris. "If you are experiencing brittle nails, it may be indicative of thyroid symptoms or hypothyroidism."

Because the thyroid gland also controls sweat levels, you may notice that you sweat less as the gland becomes less active. As your body loses this natural source of moisture, your nails, skin, and hair are likely to become increasingly dry.

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You may experience other nail symptoms related to thyroid disease.

Woman looking at her nails

Brittle or slow-growing fingernails are not the only nail-related symptom you may notice if you have an underactive thyroid. According to the American Academy of Dermatology Association (AADA), your nails may develop visible ridges. They might also become softer and shinier, appear curved, and peel, break or crumble more easily.

Some patients with an underactive thyroid may also notice that their fingernails lift up, splitting from the nail bed. This condition is known as onycholysis, and is also referred to as "Plummer's nails." Onycholysis can give the appearance of white discoloration, due to the presence of air underneath the nail. Speak with your doctor if you notice this symptom, which experts say could be among the first signs of a thyroid problem.

Look out for these other symptoms of hypothyroidism.

Woman stepping on scale with measurement tape

Hypothyroidism can also cause a range of symptoms that are unrelated to your fingernails. Many of these are easily overlooked, or mistaken for other conditions. People often tend to dismiss them as natural consequences of aging, or minor inconveniences. Since symptoms typically develop slowly, revealing themselves over the course of years, they can seem like a normal part of life, rather than setting off alarm bells.

However, if you notice more than one of the following symptoms, it's important to bring it up with your doctor and ask about being screened for hypothyroidism. Common symptoms include fatigue, weight gain, cold intolerance, and depression. Some people with hypothyroidism also experience sleep apnea, infertility, constipation, muscle pain, hair loss, hoarse voice, facial swelling, difficulty concentrating, heavy periods in women, and erectile dysfunction in men.

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A blood test can help you reach a diagnosis sooner.


It may be difficult to piece together a diagnosis from your constellation of thyroid symptoms, but experts say that when you do get an answer, treatment is usually fairly straightforward. "Accurate thyroid function tests are available to diagnose hypothyroidism," explains the Mayo Clinic. "Treatment with synthetic thyroid hormone is usually simple, safe, and effective once you and your doctor find the right dose for you."

Though several testing options are available, the gold standard for diagnosing hypothyroidism is a TSH test. This is a blood test that measures the level of thyroid-stimulating hormone (TSH) in your system, as well as the level of thyroxine, the main hormone produced by your thyroid gland. If TSH levels are high and thyroxine levels are low, it's a sure sign that an underactive thyroid is to blame. "TSH tests also play an important role in managing hypothyroidism," the Mayo Clinic explains. "They help your doctor determine the right dosage of medication, both initially and over time."

Even absent clear symptoms, your doctor may wish to perform a thyroid function test. "Doctors can diagnose thyroid disorders much earlier than in the past—often before you experience symptoms," says the Mayo Clinic. Testing can function as an early warning system, alerting your doctor to trouble and allowing you to get treatment sooner, says the American Thyroid Association. As always, talking to your doctor about any concerns you may have is the crucial first step.

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Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more
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