Nail disorders have a variety of causes, from wet work to fungi to trauma. Two recent articles in the consumer press highlighted the common – and uncommon – causes of nail disorders, including systemic health issues. Verywell Health wrote about the nail signs of high blood sugar, while Women’s Health wrote about the dermatological and systemic causes of white spots on the nails.
For what to know about nail signs of systemic disease, I interviewed dermatologist Shari Lipner, MD, PhD, FAAD, professor of dermatology and director of the nail division at Weill Cornell Medicine. Dr. Lipner will lecture on clinical pearls for nail disease in skin of color patients at Skin of Color Update.
The Verywell Health article includes the line, “Nails are a mirror of general health.” Have you found that to be true? If so, what systemic conditions have you diagnosed in your patients as a result of a nail examination?
Nails can be a mirror of general health. I have diagnosed patients with yellow nail syndrome with bronchiectesis, clubbing with interstitial lung disease, and koilonychia with iron deficiency. When I was rounding with a dermatology resident on the wards, I even diagnosed a patient with splinter hemorrhages with a cardiac myxoma!
In your clinic, what nail signs would prompt you to encourage a patient to have their blood sugar level tested?
There is not a single nail sign that is specific or diagnostic of diabetes. Clinical findings consistent with onychomycosis, such as onycholysis and subungual hyperkeratosis with confirmatory testing, along with recurrent paronychia or onychocryptosis, and dermoscopic microhemorrhages or splinter hemorrhages of the nail plate, should prompt screening for hyperglycemia, particularly when accompanied by distal sensory neuropathy.
How do you differentiate between the more common causes of these nail changes and when the changes might stem from high blood sugar?
I would recommend trying to confirm the diagnosis when possible. Examples would be performing a clipping with histopathology, a scraping for KOH or fungal culture for onychomycosis, or observing characteristic features of nail psoriasis, such as nail pitting along with onycholysis, and scaly erythematous plaques on the skin. You could test for diabetes, if the nail findings are not consistent with a known etiology, especially if there are other dermatological signs of diabetes, such as acanthosis nigricans.
White spots on the nails – leukonychia — is another nail condition with a possible systemic cause. What questions do you ask your patients to help determine the origin?
I try to ask questions that could help me distinguish between true leukonychia, including trauma, drugs, or nutritional/systemic causes from apparent leukonychia, including hepatic, renal, cardiac disease or hypoalbuminemia, and pseudoleukonychia, including onychomycosis or keratin granulation. Key questions include whether the white area moves with nail growth, medical history, drugs and chemotherapy, as well as exposures, including nail trauma from manicures, diet, and family history.
What are possible systemic causes of leukonychia, and what signs would lead you to consider these causes?
Apparent leukonychia is a possible signal of systemic disease. Terry nails suggest cirrhosis, half-and-half (Lindsay) nails suggest chronic kidney disease, and Muehrcke’s paired transverse bands suggest hypoalbuminemia. Signs that should prompt a workup (albumin, LFTs, renal function, CBC) are symmetric involvement of all or most nails, whitening that blanches without migrating distally, and bands that correlate in time with a systemic illness.
What else should dermatologists know about nails as an indicator of systemic health?
Close examination of the nails may identify early signs of systemic disease. Always exclude trauma, psoriasis, and onychomycosis, and correlate with concurrent clinical findings.
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