What Your Nails Say About Your Health

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Hold that polish! Or at least give your nails a good look before you paint them. Your fingernails and toenails are like 20 mini-mirrors to the state of your overall health. Changes throughout the body that are otherwise invisible can sometimes be first seen in the nails, says dermatologist Amy Newburger, a senior attending physician at St. Luke's - Roosevelt Medical Consortium in New York City.

Fingernails tend to give more reliable clues than toenails, given the wear and tear of walking, tight shoes, and slower foot circulation over time, which can obscure toenail changes. But check both hands and feet -- the first of the following nine nail clues explains why.

Clue 1: A black line

Look for: A black discoloration that's a straight vertical line or streak and grows from the nail bed, usually on a single nail. About 75 percent of cases involve the big toe or the thumb, according to a review in the British Journal of Dermatology. Especially worrisome: a discoloration that's increasing or that's wider at the lower part of the nail than the tip. "That tells you that whatever is producing the pigment is producing more of it," says Newburger.

Also beware when the skin below the nail is deeply pigmented as well, says podiatrist Jane Andersen of Chapel Hill, North Carolina, a spokeswoman for the American Podiatric Medical Association.

What it might mean: Melanoma, the deadliest form of cancer. People with darker skin are more vulnerable than Caucasians to subungual melanoma (melanoma of the nail bed), but darker-skinned races also have more dark lines in nails that are benign, according to a 2004 report in American Family Physician.

Next steps: Always have a doctor check out a suspicious black line on the nail quickly because of the high skin cancer risk. A black line on the nail may also be caused by a harmless mole or an injury. A biopsy can confirm melanoma.

Clue 2: Small vertical red lines

Look for: Red (or sometimes brownish red) streaks in the nail. "They look like blood or dried blood," Anderson says. These are known as "splinter hemorrhages" because they look like a splinter but are caused by bleeding (hemorrhage) under the fingernail or toenail. They run in the same direction as nail growth.

What it might mean: Heart trouble. The "splinters" are caused by tiny clots that damage the small capillaries beneath the nail. They're associated with an infection of the heart valves known as endocarditis. Don't panic if you see one, though: Sometimes an ordinary injury to the nail can cause a splinter hemorrhage.

Next steps: No treatment is needed for the splinter hemorrhage itself. A doctor can evaluate and treat the underlying cause if it's heart-related.

Clue 3: Wide, "clubbed" nails

Look for: Uniformly widened fingertips or toes -- they appear to bulge out beyond the last knuckle -- where the nails have widened, too, so that they curve down and appear to wrap around the tips of the finger like an upside-down spoon. (Normal nails are narrower than their base fingers.) These extra-wide nails are called "clubbed" nails.

What it might mean: Clubbed nails are a common sign of pulmonary (lung) disease, Newburger says. Although the nails' odd shape develops over many months to years, people are often unaware of the underlying condition, which can include lung cancer.

Next steps: If you haven't had a physical exam lately, consider one, especially if you have other symptoms such as coughing or shortness of breath.

Clue 4: Spoon-like depressions

Look for: Nail beds that have little dips in them, an effect called koilonychia, or "spooning." "If you put your hand flat on the table, the spooned nails look like they could each hold liquid," Newburger says. The nails will also be unusually pale or stay whitish for more than a minute after you press gently on one. (Normally it would turn white for a second or two before returning to its original pinkish color.) The moons at the base of the nails may look particularly white.

What it might mean: Iron-deficiency anemia. Spooning can also be seen in the nails of people with hemochromatosis, or "iron overload disease," a condition usually caused by a defective gene that leads to too much iron being absorbed from the gastrointestinal tract. Other symptoms for both conditions can include fatigue and lack of energy, or they may be symptomless.

Next steps: A complete blood count can diagnose anemia, and a physical exam might pinpoint the cause of iron problems. Iron supplements and dietary changes are often prescribed as first-line treatments for anemia.

More things your nails say about your health

Clue 5: Rippled, pitted nails

Look for: Tiny indentations or holes in the nail bed called "pits." The nail may also appear to be rippled rather than smooth. (You can also feel these abnormalities by rubbing your finger across the nail, which is normally as smooth as the inside of a seashell.)

What it might mean: Psoriasis. Between 10 and 50 percent of patients with this common skin disease have pitted, hole-pocked nails, according to a 2000 report in Primary Care. So do more than three-fourths of those with psoriatic arthritis, a related disorder that affects the joints as well as the skin. More rarely, Reiter's syndrome and other diseases of connective tissue show this symptom.

Next steps: A doctor can prescribe medications to treat the underlying conditions. The nail bed can often be restored in psoriasis when the treatment starts early.

Clue 6: Brittle nails

Look for: Peeling, splitting, or easily cracking nails. Sometimes vertical ridges mar the surface, too. These telltale wrecked nails are sometimes called "hypothyroidism nails."

What it might mean: Thyroid disease. Hypothyroidism, or underactive thyroid, occurs when the thyroid gland doesn't make enough thyroid hormone. (Typically a patient's hair is also thin and brittle.) Metabolic functions throughout the body are disrupted, including the delivery of moisture to the nails. Pale, dry skin and hair that may fall out are related signs. Hyperthyroid (overactive thyroid) diseases, such as Grave's disease, may also cause brittle nails.

Next steps: Skip the over-the-counter nail strengtheners for persistently brittle nails and get thyroid levels checked; if thyroid disease is the cause, it's important to treat the root problem.

Clue 7: Nails that seem to be "lifting off"

Look for: The nail itself separating from the nail bed, which is the layer of skin directly under the nail. This effect, known medically as onycholysis, often begins at the fourth or fifth fingernail. Toes can also be affected. It's also called "Plummer's nails" (after the physician Stanley Plummer, who described them in 1918) or "dirty nails," because debris can accumulate and be seen.

What it might mean: Thyroid disease. Hyperthyroidism, in which too much thyroid hormone is produced, can cause excessive nail growth and lead to this deformation. Plummer's nails tend to occur in younger patients rather than older ones.

Next steps: Other hyperthyroidism symptoms to be aware of include fatigue, difficulty concentrating, increased appetite, weight loss, sweating, hair loss, itching, and protruding eyes.

Clue 8: Depressions running across the nail horizontally

Look for: White ridges running across the width of the nail bed. These so-called "Beau's lines" (after the French physician who described them) can occur in all or just one nail; if in all nails, they're at about the same place on all of them. They're actual ridges in the nail plate itself.

What it might mean: Diabetes, psoriasis, Raynaud's disease -- or just a trauma to the nail. Beta-blockers and drugs used in chemotherapy can also produce Beau's lines. Some people develop them simply as a result of aging.

Next steps: Consider this effect just one piece of a puzzle. Nails grow about 1 mm every six to ten days, so doctors use this measurement to estimate when the problem might have begun.

Clue 9: White bands running across the nail horizontally

Look for: The white-colored bands, known as "Mees' lines," run transverse (parallel to the white tips of the nails). They may affect one nail or several, occurring at about the same spot on each nail. Because the problem is in the nail itself, the line moves forward as the nail ages -- allowing doctors to date the time the problem began.

What it might mean: Arsenic poisoning! Hair and tissue samples should be tested to verify. It's pretty rare these days, Anderson says, but worth knowing about.

Next steps: Make an appointment to see a doctor -- and avoid eating anything you don't prepare yourself!

Paula Spencer Scott

Paula Spencer Scott is the author of Surviving Alzheimer's: Practical Tips and Soul-Saving Wisdom for Caregivers and much of the Alzheimer's and caregiving content on Caring. See full bio

over 1 year, said...

The overall test for thyroid function is the TSH, then your doctors should also be checking T3, T4, and Free T3. Periodically, your parathyroid, calcium, and vitamin D should also be checked. The TSH only checks the overall function of your thyroid and often does not give accurate lab values in regards to whether medications need to be adjusted or even if an individual needs to be taking medication. The parathyroid is integral to how the thyroid functions, therefore it's incredibly important it's ensure that's functioning properly. Part of the parathyroid's function is to control the absorption of calcium which then impacts the the absorption of vitamin D. That's why these tests are also important. I get these labs done every 6 weeks to 3 months. You do NOT need 3 vials of blood drawn just for the thyroid panel. In fact you don't even need that many for all of these tests. They draw 2 vials for these tests listed here. That's it, 2 vials.

almost 2 years, said...

Ive had a problem with both my ring toenails but its worse in my right foot. Ive had this problem since I was about. It seems that the nail is a little darkish black on the right half of the toenail . When I was going to cut it I noticed it was really really thick and soft and was connected to my skin. I pressed down on all my toes and none of them hurt except the ring one. I was thinking it could be an injury because I played sports when I was 11 but I don't know. I really want to fix it...

over 2 years, said...

My 27 year old daughter just discovered a black line on her pinky toe nail bed. Is this concerning?

over 2 years, said...

I get the ones where a depression runs across the nail horizontally- the first time I noticed that happening was when I was working in a factory in the paint room. They weren't careful of the fumes and we'd get lots of exposure during the shift. I would come home and the paint would be in my nostrils. I would eventually get really dizzy every day, but I accidentally got pregnant (and miscarried, due to the paint exposure), and quit. My nails grew like that, and even after not working there for 15 years, they still grow like that, but not as pronounced, so maybe it could also be from chemical exposure?

over 2 years, said...

are any of these life threating disease.

almost 4 years, said...

i hav dark line on my finger nail , i jst want to confirm dat wts the cause of it , den i read dis article , den i got scared , plz help mee and tell me what should i do ????

about 4 years, said...

A very interesting and worthwhile article.

about 4 years, said...

Since my chemo, for breast cancer, my fingernails and toenails have not been the same. Ridges, brittle, and look icky.

about 4 years, said...

Yes been having problems with nails. Already diagnosed with Hypothyroidism, and Hemochromotsis. So need to get in for my annual check up for blood and thyroid. Thanks so much:-)

about 4 years, said...

As I've aged, I have noticed changes in my fingernails. This article was a wakeup call to pay more attention to the changes.

over 4 years, said...

What if a fingernail looks withered and stops growing. Just a pinky?

about 5 years, said...

I have an orange line down my thumb nail. It never seems to go and I've had it a while now, just woundered if anyone knows what it is ? Thanks tom

about 5 years, said...

This article about the toes is helpful because my big toe has darkened over the years and it scares me.

over 5 years, said...

Interesting to know what the different things on the nail could mean!

over 5 years, said...

Thank you for the information. Very helpful!

over 5 years, said...

I have vertical ridges and have just researched other websites, including the Mayo Clinic. Most state they are mostly harmless and offer no ill health affects. One site indicated the cause might be dehydration and a decrease in estrogen. I am intrigued that there might be an issue of hypothyroidism. I have had them for some time and they are getting worse. I turned 59 in January 2013.

over 5 years, said...

Thank You.

over 5 years, said...

Great article. Hemachromatosis can actually be a lot more complicated to diagnose, and many doctors don't even know this! It is possible to be iron deficient but not anemic.

over 5 years, said...

Another cause for clue #6, ripples: When I shipped out, it was for 10 days out and 4 days ashore. The ship's stewards department was all black. They used hog lard in every meal. I had ripples in all my nails until I quit.

over 5 years, said...

I have nail discoloration and abnormalities . I have a doctor's appointment to have it diagnosed.

over 5 years, said...

My finger nails keep cracking about a 1/4 of a way down my nails. Now after getting dressed this morning one of my toe nails is broken literally in the middle. If I take clippers to it (hopefully it won't hurt), i will have 1/2 of a toe nail. Does this mean something? Are my nails trying to tell me something?

over 5 years, said...

Dreading biopsies under 2 nails in a few days ( no local anesthesia :( for splinter hemorrhages ( apparently). I've had them before, the dermalologist appears not concerned, just verifying, since we set the appointment it has been 2 weeks and they have 'grown out' to the point I have kept them protected in hopes he can just painlessly snip the ends off for the biopsies. I was interested to learn today about the endocarditis connection, while I am not aware of an infection, I am (have been0 monitored for several years and will have an aortic valve replacement probably within a couple years. I see the cardiologist every 6 months and didnt have the nail 'splinters' last time ( not would I have thought to mention it to him if I had). Your comments please about the liklihood of a melanoma gorwing out with the nail bed, and about the valve connection and whether I should contact cardiologist ahead of schedule to mention this ?? thanks very much..

over 5 years, said...

I have one toe nail that has turned white from the base and not sure what this means..

over 5 years, said...

I have had brittle 2nd and 4th fingernais which also peel off. I have neen diagnosed twice as paronychea, our on. Been 2 did no clear, then told fungal, put o meds,creams dermatologist. It has been going on over 2 mo. The will split split down to cuticle peel near skin. It hurts! The main thyroid blood test did not indicate hyper or hypothyroid. One on rt hand, one finger on left. Help!

over 5 years, said...

It let me know that my fingernails are ok. They just don't want to grow, and they break easily. The nail on my right thumb splits on the right side about 1/8 inch from the right. I have been taking OTC Biotin tabs recently. I hope that helps with growth and strength.

over 5 years, said...

Description of nail abnormalities, as I am having issues with my nails. Wow, it really means something. Thanks.

almost 6 years, said...

For those that are on Thyroid medication-Synthroid, Levothyroxin, etc., there are three lab tests that should be done for Thyroid function. If your doctor is not having the lab draw three tubes of blood, you are not having a full panel done. It is possible you are still Hypothyroid even though the one test your doctor has run looks OK. Tell him to run all three- look up in WebMD. If you doctor won't comply, go to an Endocrinologist -this is all they do is check endocrine levels such as Thyroid and they will draw/check all three. It's important to have all three checked. And, yes, your vertical, brittle nails are from Hypothyroidism. You may also not be processing the synthetic form of thyroid (Synthroid and Levothyroid, Levothyroixin, etc.) You may need Armour Thyroid which is porcine Thyroid ( Yes, from the Armour Ham pigs- specially contracted with the manufacturer to provide the thyroid of the pigs for medicinal use.) Unless it is a cultural/religious issue, this form of Thyroid is much more effective.