If you have soft, scooped-out fingernails with a depression in the middle, you could have iron-deficiency anemia. Your nails can also signal other health conditions, if you notice nail pitting or transverse lines called Mees' lines.
Symptoms of Anemia
The World Health Organization lists iron deficiency as the most common nutritional disorder in the world. Your body uses iron for a variety of functions, crucially to help transport oxygen from the lungs to your organs and tissues. Iron deficiency can reduce oxygen transport, and because iron also helps maintain your skin, hair and nails, a lack of oxygen can affect all of those things.
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Symptoms of iron-deficiency anemia include fatigue, dizziness, pale or "sallow" skin, a rapid heart rate, cold hands and feet, a swollen or inflamed tongue and feeling weak. To treat iron-deficiency anemia, your doctor might recommend increasing your dietary iron intake, taking iron supplements or receiving intravenous iron.
Iron is found in both animal and plant-based foods. Heme iron, found in animal products, is easier for the body to absorb than nonheme iron found in plant foods. That's why people who eat a vegetarian or vegan diet may be more susceptible to iron-deficiency anemia than people who eat meat.
Anemia and Fingernails
Alongside the other symptoms, anemia affects nails in some people. One example is koilonychia, which MedlinePlus describes as a fingernail abnormality where "the nail has raised ridges and is thin and curved inward." The condition, also known as "spoon nails," is associated with iron-deficiency anemia. According to the Mayo Clinic, spoon nails are soft and often have a "scooped out" look. Each nail has a depression large enough to hold a drop of liquid.
Besides anemia, a few other things can cause koilonychia. High altitude, a nail injury or trauma and exposure to petroleum products have all been linked to the condition. In some cases, koilonychia is genetic.
What Does Nail Pitting Signal?
Spoon nails are different from nail pitting, a condition where there are small dents in your nails that look like they were made with an ice pick. The American Academy of Dermatology says that nail pitting can be a symptom of psoriasis, atopic dermatitis or alopecia areata.
- Psoriasis is a skin condition that causes inflammation and scaling. According to Harvard Health Publishing, psoriasis is an immune system disorder where skin cells develop at a much faster rate than usual. Psoriasis has genetic and environmental causes and ranges from mild to severe. There are also many forms of psoriasis. "About 90 percent of patients have the plaque type, with sharply demarcated salmon-pink plaques of inflamed skin covered by silvery scales," Harvard Health Publishing says.
- Atopic dermatitis, also called eczema, makes your skin red and itchy. Symptoms of eczema can include dry skin, itching, red or brown-gray patches of skin, small raised bumps on the skin and cracked, thickened or scaly skin. Scratching can also cause skin irritation or cracking.
- Alopecia areata is a medical condition where your hair falls out in round patches. It happens when your immune system attacks your hair follicles. According to the American Academy of Dermatology, nail pitting can be one of the first symptoms of alopecia areata.
Read more: Do Vitamin Deficiencies Cause Fingernail Ridges?
What Are Mees’ Lines?
Stanford Medicine describes Mees' lines as transverse white lines across each fingernail. The bands are about 1 to 2 millimeters thick and span the entire width of the nail. There's usually one line per nail, and the lines can disappear when you apply pressure to the nail. Stanford notes that the condition is "strongly associated" with thallium poisoning, arsenic poisoning and, sometimes, to other types of heavy metal poisoning.
According to an article in the May 2016 issue of the Cleveland Clinic Journal of Medicine, Mees' lines are associated with acute systemic stress from conditions like heart failure, acute kidney failure, infections like measles and tuberculosis, breast cancer, ulcerative colitis and systemic lupus. The journal also points out that, if Mees' lines are caused by arsenic poisoning, "they can also be used to identify the time of poisoning, since they tend to appear two months after the initial insult."
Common Nail Conditions
Merck Manuals notes that other common nail conditions include:
- Fungal infections like onychomycosis, which can affect both fingernails and toenails. The fungus causes nails to become thickened, rumbly, brittle or ragged and can be treated with oral antifungals or a medicated nail polish or cream.
- Ingrown toenails, which involves a curved nail growing into your skin. You can treat an ingrown toenail by lifting or removing the ingrown portion of the nail.
- Nail bed injuries, typically caused by accidents. These can cause blood to pool in the nail bed, or they can crack or tear off the nail. "Collections of blood are drained by making a small hole in the nail in order to relieve the pressure and provide pain relief," the American Society for Surgery of the Hand says. "More serious injuries may be treated with surgery and/or need splinting."
- Thick toenails often develop with age, though this can also be a sign of nail fungus.
Treating Weak Nails
If iron-deficiency anemia affects your nails, treating the anemia should also resolve the nail issues. If your nails are still thin or brittle when your iron levels have increased, there are a few things you can try to restore your nail health.
- A nutritional supplement called biotin might help strengthen anemia-weakened nails. The National Institutes of Health Office of Dietary Supplements says there's mixed evidence on how useful biotin is to treat soft nails, but taking a safe dosage of biotin has few side effects and may make a difference.
- You can also apply a protective layer to your nails. The Mayo Clinic says that a protective nail polish can help prevent your nails from splitting or breaking. Plus, you should avoid using harsh nail products like a nail-polish remover with acetone, opting instead for an acetone-free version.
- MedlinePlus: "Nail Abnormalities"
- Mayo Clinic: "Fingernails: Possible Problems"
- American Academy of Dermatology: "12 Nail Changes a Dermatologist Should Examine"
- Harvard Health Publishing: "Psoriasis"
- Mayo Clinic: "Atopic Dermatitis (Eczema)"
- American Academy of Dermatology: "Alopecia Areata"
- Stanford Medicine: "Examination of the Hand (the Hand in Diagnosis)"
- Cleveland Clinic Journal of Medicine: "Evaluation of Nail Lines: Color and Shape Hold Clues"
- World Health Organization: "Anaemia"
- Mayo Clinic: "Is it Possible to Prevent Split Fingernails?"
- National Institutes of Health: Office of Dietary Supplements: "Biotin"
- Merck Manuals: "Overview of Nail Disorders"
- American Society for Surgery of the Hand: "Nail Bed Injuries"