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Believe it or not, your nails can say a lot about your overall health, including how well your thyroid functions. Among those with low thyroid levels (hypothyroidism), common nail complaints include weak nails that break easily, grow slowly, or are thin. In contrast, those with elevated thyroid hormone levels (hyperthyroidism) may report “spoon-shaped” nails or clubbing.
As you can see, having too much or too little thyroid hormone can affect the appearance of your nails. Ahead, learn why, and discover helpful tips to keep your nails healthy.
Apart from scratching an itch, fingernails have many functions you might not even realize. For example, your nails:
- Protect against injuries to nerves located in your fingers and toes
- Prevent infections by keeping germs out
Nail growth starts at the nail root, located at the bottom of your nail. You can’t see it because a thin layer of skin called the cuticle protects it. As new skin cells form in the nail root, they push the nail forward, causing your nails to grow.
The main part of the nail is known as the nail plate. The nail plate is made of keratin, a protein that makes your nails hard and strong. As your nails grow, they attach to the nail bed below it, which contains nerves, blood vessels, and melanocytes, giving nails their pinkish-red color.
Typically, nails are smooth, but nails can sometimes split or develop ridges. Various medical conditions can affect the growth and health of your nails, including the following:
- Thyroid dysfunction
- Fungal or bacterial infections
- Iron deficiency
- Psoriasis, a skin disorder that causes red, scaly patches associated with itching, pain, or bleeding
- Medications, especially ones used to treat cancer
- Chemical agents
The American Academy of Dermatology Association recommends routinely checking your nails. If you notice any of the following characteristics, they may be signs of another medical condition.
- Dry, brittle, and thick nails with visible ridges
- Nails that are soft and shiny
- Change in nail growth rate, either too fast or slow
- Nail peeling
- Nails that break or split easily
- Nails that lift away from the nail bed
- Curved nails with swollen fingertips and thicker skin just above the nail
Generally, thyroid hormones help with growth and development, including nail growth. Nail changes may help with the early detection and diagnosis of a thyroid disorder.
According to a 2022 study, those with a thyroid disorder frequently report nail brittleness. In fact, those with autoimmune thyroid disorders like Hashimoto’s or Graves’ disease had a higher percentage of nail brittleness than those with a non-autoimmune thyroid condition.
Onycholysis, also called Plummer’s nail, is a condition where the nail plate pulls away from the skin of the nail bed. This condition is more common in those with hypothyroidism than hyperthyroidism. To a lesser extent, those with hypothyroidism also reported the following nail-related conditions:
- Leukonychia (white nails)
- Striped nails
- Pitting (small depressions on nails making an uneven surface)
How exactly a dysfunctional thyroid gland affects nail growth is not entirely understood. In the case of hypothyroidism, we know that it causes our body to slow down, which some believe may result in the following:
- Keratin builds up in the nail plate before it grows out, causing ridges; or
- Reduced blood flow and nutrients to your nails result in slow growth and brittle nails.
Determining what is causing your nails to change will help guide treatment. For instance, your healthcare provider will prescribe appropriate medication if your nail issues are due to a fungal or bacterial infection. But if your thyroid levels are the root cause of nail issues, the first course of action is thyroid hormone replacement treatment to help better manage your thyroid hormone levels.
Nail health and appearance should improve over time after treatment.
The American Academy of Dermatology Association recommends these tips for keeping your nails healthy:
- Keep your nails dry and clean.
- Regularly trim your toenails.
- Cut your nails straight across using sharp nail clippers. Rounding the tips of your nails can help strengthen them.
- Avoid biting, picking, or tearing your nails.
- Do not remove your cuticles, especially during a pedicure or manicure, as nail damage can occur.
- Wear water shoes or flip-flops in public showers and at the pool.
- Clip your hangnails or ingrown nails. Don’t dig them out.
Nail care approaches can also help protect nails and prevent breakage. Applying a nail hardener can help strengthen nails. Keeping your hands, nails, and cuticles well moisturized also helps keep your nails healthy.
Additionally, applying lotions containing alpha hydroxy acids or lanolin and wearing gloves while washing dishes or doing other water-intensive tasks can help prevent brittle nails caused by frequent wetting and drying.
You may have heard of or seen supplements that claim to improve hair and nail growth. These supplements typically contain high doses of a water-soluble B vitamin called biotin. There is some evidence that biotin supplements can prevent nail splitting and breakage and may help protect against hair loss as well.
An important note about biotin: Biotin can interfere with your thyroid test results. So, if you are taking biotin, you should stop about 48 hours before having thyroid tests. (Note: if you are using Paloma’s Complete Home Thyroid Test kit, you don’t need to stop taking biotin, as this test is unaffected.)
Changes in the appearance of your nails could indicate a medical condition, including thyroid dysfunction. As mentioned above, talk with your healthcare provider if you notice any nail changes. They may recommend checking your thyroid function.
Testing your thyroid can easily be done from the comfort of your home using Paloma’s at-home testing kit. It only takes a small, finger-prick blood sample to know how well your thyroid functions. You can expect your results within a week with an interpretation of what your labs mean.
If the underlying cause of your brittle nails or onycholysis is hypothyroidism, make an appointment with one of Paloma’s thyroid specialists to determine your next steps. This may include starting on a thyroid replacement medication, such as levothyroxine or Armour Thyroid. These medications help restore your thyroid hormone levels when they are low. Over time, as your thyroid hormone levels normalize, your nail health should improve.