A subtle symptom in your fingernail could be a sign of congestive heart failure, cancer, psoriasis — or an STI

Your nails might be trying to tell you something — and checking them could be the easiest way (hands down) to spot hidden health problems.

Meaning “little moon” in Latin, lunulae are the half-moon shapes at the base of your nails. It’s where new nail cells are made and pushed forward. They’re most prominent on your thumbs and are smaller and less visible as you move out to the pinkies.

Researchers analyzed studies going back to 1954, when the first research was published on a particular kind of unusual lunulae, to find exactly what the mini-moons can tell us about our health.

Lunulae are usually white, because the nail is thicker there, obscuring the blood vessels on the nail bed. That said, not everyone has them, and not having lunulae doesn’t indicate you’re unhealthy.

But when you have lunulae that turn red, it could spell danger. “Red lunulae may reflect both systemic disease activity or local pathology,” the authors wrote.

What reserachers found

Nails are highly sensitive to health changes in the body. It needs a steady flow of nutrients, oxygen, and blood flow to grow continuously, and changes to any of these will affect the way they grow.

For example, using GLP-1s has recently shown to be associated with discolored and detached nails.

That’s why we’re been looking to our nails for so long as indicators of health. Back in that first 1954 report, researchers in London observed 61% of folks examined with red lunulae also had heart failure.

All the others with red lunulae had some kind of systemic disease like emphysema and chronic bronchitis (both known as COPD), cirrhosis (longterm liver scarring), and cancer, including polycythemia vera (a blood cancer that causes thick, slow moving blood), lymphoma (cancer of white blood cells), and myeloid leukemia (cancer of blood and bone marrow).

Since then, more research has shown red lunulae are connected with autoimmune conditions like alopecia areata (which causes the hair to fall out in round patches), dermatomyositis (which causes skin rashes and muscle weakness), and systemic lupus erythematosus (aka SLE, which attacks healthy tissue and organs.)

Author also note connections with congestive heart failure, psoriasis, carbon monoxide poisoning, and lymphogranuloma venereum (LGV), a sexually transmitted infection caused by certain variants of the Chlamydia bacteria.

But exactly why red mini-moons on your nails are connected to any of these conditions “remains unclear,” authors say.

They do point out though, that the association only exists if multiple fingernails have red lunulae — if it’s just one, something local like an injury under that nail, is more common.

It’s also important to note that having a red lunulae doesn’t necessarily mean something’s wrong, just as having white ones doesn’t mean you’re perfectly healthy.

Authors say that the review simply shows support for more investigation if a patient comes in with red lunulae.

“Given the rarity of the occurrence, its potential diagnostic relevance is often overlooked,” write the researchers.

“When identifying red lunulae, clinicians should consider connections to underlying systemic or dermatologic disease. This subtle clinical sign may facilitate early detection and identification of salient systemic disease.”