Do not wait for nail changes before getting screened if you have risk factors. Diabetes, high blood pressure, cardiovascular disease, a family history of kidney disease, and older age all increase the likelihood of chronic kidney problems.
5. Beau’s lines: horizontal grooves across the nails
Beau’s lines are horizontal indentations or grooves that run from one side of the nail to the other. They form when the nail matrix—the growth area beneath the cuticle—temporarily slows or stops producing nail tissue because the body is under significant stress.
A severe illness, hospitalization, major infection, surgery, acute kidney injury, or substantial electrolyte disturbance may create this kind of interruption. Once nail growth resumes, the groove becomes visible and gradually moves toward the fingertip as the nail grows. In that sense, a Beau’s line can act like a timeline of a previous health event.
Multiple grooves may reflect repeated episodes of serious illness, although they can also result from trauma, chemotherapy, uncontrolled diabetes, or other systemic stressors. A single horizontal groove does not prove that you have kidney disease. Still, if you remember being seriously ill around the time the groove formed—or if new grooves keep appearing—mention it to your doctor.
Unlike vertical ridges, which are common and often harmless, horizontal grooves deserve more careful consideration when they are deep, widespread, or associated with other symptoms.
Bonus sign: Muehrcke’s lines
A rare finding called Muehrcke’s lines consists of two pale horizontal bands that appear across the nail with a normally colored strip between them. Unlike Beau’s lines, Muehrcke’s lines are caused by changes in the tissue beneath the nail, not by an interruption in nail growth. As a result, they do not move toward the fingertip as the nail grows and may fade when the underlying condition improves.
Muehrcke’s lines have been associated with very low blood albumin levels, including those seen in nephrotic syndrome. In nephrotic syndrome, the kidneys allow unusually large amounts of protein to leak into the urine. The resulting low albumin level can contribute to swelling, particularly around the feet, ankles, legs, or eyelids.
Muehrcke’s lines are uncommon and are not exclusive to kidney disease. They may also occur in people with severe malnutrition, liver disease, or other conditions that lower albumin. If you notice this pattern, your doctor may order a serum albumin test, urinalysis, and urine albumin-to-creatinine ratio.
What to do if you notice a nail change
Start by taking a clear photograph of the nails without polish and note when you first noticed the change. Then consider whether you have other symptoms, such as persistent tiredness, swollen legs or feet, itchy skin, nausea, easy bruising, foamy urine, blood in the urine, or a significant change in how often you urinate.
