Leukonychia (white nails, white spots on the nails)
BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.
Isolated white spots or streaks (punctate or transverse leukonychia)
- No laboratory tests: traumatic or cosmetic cause in the great majority of cases.
Do not order
- Serum calcium, ferritin or “deficiency screen” for isolated white spots: punctate leukonychia is not linked to lack of calcium or iron; it is most often traumatic [2].
Pseudo-leukonychia: suspected onychomycosis
Mycological sample
- Mycological sample from the affected nail (direct examination and culture)
- No topical antifungal (nail lacquer, film-forming solution) or systemic antifungal for 3 months; nails scrubbed with neutral soap on the day of sampling.
- HIV serology (if fungal leukonychia starting from the lunula)if neededProximal subungual onychomycosis (leukonychia that appears at the lunula, often on several nails): a rare form that readily occurs in an immunocompromised host [3]. In a controlled Strasbourg study, leukonychia affected 14.3% of patients infected with HIV and onychomycosis 30.3% (versus 12.6% of controls), more so as immunosuppression was advanced; acquired total leukonychia of all 20 nails was present in 4% [6].
Do not order
- “Trial” antifungal treatment before sampling: sampling must precede any local or systemic treatment, which makes it negative for 3 months [3].
White nails on all fingers (Terry's nails, Lindsay's nails, Muehrcke's lines)
Laboratory tests
- FBC
- Serum albumin
- Serum creatinine with eGFR
- AST
- ALT
- GGT
- PT (if Terry's nails or signs of liver disease)if needednon-French guidelineTerry's nails (white nail with a pink distal band of 1 to 2 mm), found in more than 80% of cirrhotic patients in Terry's series [2].
- Fasting plasma glucose (if Terry's nails)if needednon-French guidelineTerry's nails, also described in adult diabetes, heart failure and chronic renal failure [2].
Sources (9)
- Yalçinkaya İyidal A, Erduran F, Hayran Y, Gür Aksoy G, Yakut Hİ, Aktaş A. Epidemiological and clinical features of nail disorders in patients presenting to a pediatric dermatology outpatient clinic: a cross-sectional study in a tertiary referral center. Medicine (Baltimore). 2026;105(35):e50346.
- Iorizzo M, Starace M, Pasch MC. Leukonychia: what can white nails tell us? Am J Clin Dermatol. 2022;23(2):177-193.
- Société française de dermatologie. Onychomycoses : modalités de diagnostic et prise en charge. Ann Dermatol Venereol. 2007;134(5 Pt 2):5S7-16.
- Assurance maladie. Nomenclature des actes de biologie médicale (NABM), version 105 : acte 5214 (prélèvement de peau ou de phanères) et cotation forfaitaire microbiologique ; absence d'acte pour l'arsenic et le thallium.
- Fawcett RS, Linford S, Stulberg DL. Nail abnormalities: clues to systemic disease. Am Fam Physician. 2004;69(6):1417-1424.
- Cribier B, Mena ML, Rey D, Partisani M, Fabien V, Lang JM, Grosshans E. Nail changes in patients infected with human immunodeficiency virus. A prospective controlled study. Arch Dermatol. 1998;134(10):1216-20.
- Velasquez-Agudelo V, Cardona-Arias JA. Meta-analysis of the utility of culture, biopsy, and direct KOH examination for the diagnosis of onychomycosis. BMC Infect Dis. 2017;17(1):166.
- Leggit JC. Nail abnormalities. Am Fam Physician. 2025;112(4):401-409.
- Frazier WT, Santiago-Delgado ZM, Stupka KC 2nd. Onychomycosis: rapid evidence review. Am Fam Physician. 2021;104(4):359-367.