“Your fingernails and toenails are extensions of your skin. Pay attention to any changes in their appearance and texture—they can provide important clues about your health,” advises Dan Baumgardt, a researcher and lecturer at the University of Bristol’s Department of Physiology, Pharmacology, and Neuroscience. Here are a few key points to watch for.
Spoon Nails
Nails on your fingers and toes should have a slight convex curve without any dips or indentations; these can indicate certain issues within the body. For instance, they may signal koilonychia, a type of nail dystrophy where the nail becomes concave. In some cases, a central indentation forms deep enough to hold a drop of liquid (hence the name “spoon nails”). Typically, nails affected in this way appear thinner and may become more brittle.
Koilonychia can indicate anemia, which means there aren’t enough red blood cells in a person’s blood to carry oxygen to the body’s tissues. This condition is often linked to iron deficiency, which can be caused by poor nutrition, for example.
Mechanics and hairdressers are particularly prone to developing koilonychia due to their work with petroleum-based solvents. However, there are many potential causes for spoon nails, so it’s wise to consult a doctor.
Discolored Nails
Healthy nail beds should be pink. A change in color, both of the nail bed and the nail itself, can occur due to illness. Yellow nails, for example, may indicate a fungal infection or changes caused by a skin condition like psoriasis.
A change in nail color to white—known as leukonychia—can be a sign of various diseases. For instance, white spots on the nails may indicate heavy metal poisoning from lead or arsenic. This is a significant issue for populations in many countries suffering from water system contamination.
If the white color spreads across the entire nail and even to several nails, the problem is likely related to a protein deficiency in the bloodstream. This could potentially indicate liver or kidney disease.
However, minor white spots on the nails usually point to traumatic injury. If you’ve ever stubbed your toe or pinched your finger, you might have noticed the nail changing color to dark purple, blue, or red. This is a subungual hematoma—a collection of blood between the nail and its bed following an injury, as reported by Science Alert.
Emergency Nail Tests
During emergency medical care, doctors often check a patient’s nails for blood oxygen saturation. This measurement is taken using a pulse oximeter, which clips onto a finger and passes light through its tip to determine the amount of blood flowing through it. By assessing how much oxygen is entering the bloodstream, the doctor can gauge how effectively your heart and lungs are functioning.
Another indicator of how well the circulatory system is working is the capillary refill time test, where the doctor presses on the nail or fingertip for five seconds, causing the skin underneath to turn white. After releasing the pressure, the skin should return to its normal color within two seconds. If this process takes longer, it may indicate that the person is dehydrated, frostbitten, or has poor peripheral perfusion. This means the heart isn’t pumping blood strongly enough, or something is obstructing the flow of sufficient blood to the body’s extremities, possibly due to shock.
Nails can also be pressed to check the response of a patient who is drowsy or unconscious. This test is part of the Glasgow Coma Scale, which measures responsiveness and the level of consciousness impairment.
What to Do If You Notice Something Unusual
This is just a brief overview of potential health issues that your nails might reveal. One thing is clear: if you’re concerned about changes in the color or shape of your nails, it’s essential to consult a doctor. And a final warning: artificial or painted nails often prevent timely detection of changes, which can hinder early diagnosis of a condition.