Your nails can reveal a surprising amount about what’s happening inside your body. Changes in color, shape, texture, and growth patterns sometimes reflect conditions affecting your heart, lungs, liver, kidneys, or blood. Most nail changes turn out to be harmless or caused by minor trauma, but certain patterns are worth paying attention to because they can be early visible signs of serious disease.
Fingernails are produced by a structure called the nail matrix, a cluster of specialized cells at the base of each nail. Each nail matrix produces 196 layers of cells that combine to form the hard nail plate. Because nails grow slowly and steadily, they essentially record disruptions to your health over time, the way tree rings record seasons of drought.
Nail Shape Changes and What They Signal
Two distinct shape changes are especially meaningful. The first is clubbing, where your fingertips gradually enlarge and the nails curve downward around them, almost like the rounded end of a drumstick. Clubbing develops when low oxygen levels in the blood persist over time, causing blood vessels in the fingertips to widen. It’s associated with lung cancer, cystic fibrosis, heart disease, and certain gastrointestinal cancers. Clubbing doesn’t happen overnight. It progresses over weeks to months, and many people don’t notice it until someone else points it out.
The second shape change is spoon nails, where the nail develops a concave, scooped-out depression deep enough to hold a drop of water. This usually starts subtly, with nails that look unusually flat before gradually dipping inward. Spoon nails are most often a sign of iron deficiency anemia. Less commonly, they can indicate iron overload, a genetic condition where the body absorbs too much iron from food.
Color Changes Linked to Organ Disease
The color of your nail bed, the pink tissue visible through the nail plate, can shift in specific patterns tied to liver and kidney problems.
Terry’s nails appear almost entirely white or washed out, with only a narrow band of normal pink color at the tip. In the 1950s, researcher Richard Terry found that more than 8 out of 10 people with severe liver scarring (cirrhosis) also had this distinctive white nail appearance. While aging can cause a milder version, pronounced Terry’s nails in a younger person are a reason to check liver function.
Lindsay’s nails, sometimes called half-and-half nails, look different: the bottom half of the nail is white, while the top half is brown or reddish. This pattern is linked to chronic kidney disease. The contrast between the two halves is usually obvious enough to notice at a glance.
Yellow Nails
Yellow nail syndrome is a rare condition where nails thicken, turn yellow or greenish, and grow unusually slowly or stop growing altogether. In some cases the nails detach from the nail bed and fall off. What makes this more than a cosmetic issue is the triad of problems it causes: nail changes, fluid buildup and swelling in the lower legs, and fluid accumulation around the lungs. Experts believe it results from problems with the lymphatic system, the network of vessels that drains excess fluid from tissues. When that drainage fails, fluid collects in the legs, lungs, and nail beds simultaneously.
Texture Changes Worth Watching
Small dents or pits in the nail surface are one of the most common texture changes. Nail pitting looks like someone pressed a pin tip or small crayon point into the nail, creating shallow or deep depressions ranging from about 0.4 to 2 millimeters across. Some people have just one or two pits, while others develop more than 10 per nail. Pitting is strongly associated with psoriasis, even in people who haven’t yet developed the skin plaques that typically define the disease. It also shows up in alopecia areata, an autoimmune condition that causes patchy hair loss.
Horizontal grooves that run across the nail from side to side are called Beau’s lines. These form when nail growth is temporarily interrupted by a significant physical stress: high fever, severe illness, surgery, chemotherapy, or poor nutrition. Because nails grow at a predictable rate, the position of a Beau’s line on the nail can give your doctor a rough timeline of when the disruption occurred. A groove halfway up the nail, for instance, points to an event several weeks ago.
White Lines Across the Nail
Muehrcke lines are pairs of white, horizontal lines that run across the fingernails, rarely appearing on the thumbs. Unlike Beau’s lines, they aren’t grooved. You can’t feel them when you run a finger over the nail, and they disappear temporarily when you press down on the nail. They also don’t grow out the way a scratch or dent would, because the problem isn’t in the nail plate itself but in the tissue beneath it.
Most people with Muehrcke lines have low levels of albumin, a protein made by the liver. Conditions that drain albumin from the body cause these lines to appear, including nephrotic syndrome (where the kidneys leak too much protein into urine), liver disease, and severe malnutrition. When albumin levels are corrected, the lines fade.
Tiny Lines That Look Like Splinters
Splinter hemorrhages are thin, dark reddish-brown lines that run vertically under the nail, looking exactly like a tiny splinter got trapped there. Most of the time, they’re caused by minor trauma you don’t even remember, like bumping your hand against something. These everyday splinter hemorrhages tend to appear near the tip of the nail and affect only one or two fingers.
The pattern becomes more concerning when multiple splinter hemorrhages show up closer to the base of the nail across several fingers at once. That distribution can be a sign of endocarditis, an infection of the heart valves. Painful splinter hemorrhages in the proximal (base) portion of several nails warrant medical evaluation, while a single painless line near the tip of one finger is almost always insignificant.
Dark Streaks and Melanoma Warning Signs
A brown or black streak running lengthwise down a nail can be completely benign, especially in people with darker skin tones, where pigmented nail bands are common. But a dark streak can also be subungual melanoma, a type of skin cancer that develops under the nail. This form of melanoma accounts for up to one third of all melanoma cases in African American, Asian, and Native American populations.
Features that raise concern include a band that is brown to black in color, wider than 3 millimeters, and has irregular or blurred borders. One of the most important warning signs is called Hutchinson’s sign, where the dark pigment extends beyond the nail itself onto the surrounding skin of the nail fold. A streak that changes in width, color, or shape over time, or one that appears for the first time after age 50, also deserves prompt evaluation. Subungual melanoma is most common between the fifth and seventh decades of life and most often affects the thumb or big toe.
What’s Usually Harmless
Not every nail change points to disease. White spots are typically caused by minor bumps to the nail matrix and grow out on their own. Vertical ridges running from the base to the tip of the nail become more prominent with age and are generally normal. Brittle nails that split or peel are most often the result of repeated wetting and drying, exposure to harsh chemicals, or simple aging rather than a nutritional deficiency.
The key distinction is pattern. A single nail that looks odd after you jammed it in a door is trauma. Changes that appear gradually across multiple nails, especially when paired with other symptoms like fatigue, swelling, or shortness of breath, are more likely to reflect something systemic. Your nails won’t diagnose a disease on their own, but they can be the visible clue that prompts the right questions.