Acanthosis nigricans
BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.
Gradual onset (obesity, insulin resistance)
Fasting laboratory tests
- Fasting plasma glucose
- Lipid profile
- ALT (in adults or overweight children)if needednon-French guidelineA dermatology review proposes ALT in adults and children who are overweight, with fasting plasma glucose and a lipid profile [1]. A 2026 systematic review cites plasma glucose, lipids and blood pressure, without ALT [2].
- HbA1c (in addition to plasma glucose)if neededProposed among the tests of insulin resistance and glycaemic status [1]; not reimbursed for screening, write “NR” [3].
Do not order
- Fasting insulin, HOMA index: frequent false positives and non-standardised assays [1]; the international PCOS guideline considers insulin assays of little clinical value and advises against them in routine practice [6].
- Routine TSH: no association with thyroid function has been established outside insulin resistance or PCOS [4].
Woman with hyperandrogenism or menstrual disorders (PCOS)
Fasting laboratory tests
- Total testosterone
- SHBG (to calculate the free androgen index)
- Oral glucose tolerance test (75 g)
- Lipid profile
- Delta-4-androstenedione (if testosterone normal)if needednon-French guidelineNormal total and free testosterone: androstenedione may be measured, bearing in mind that it is less specific [6].
- DHEA-S (if testosterone normal)if needednon-French guidelineNormal total and free testosterone: DHEA-S may be measured, bearing in mind that it is less specific and falls with age [6].
Exclusion of other causes (diagnosis of PCOS)
- TSH
- Serum prolactin
- 17-hydroxyprogesterone
- FSH
- On the combined oestrogen-progestogen pill, androgens cannot be interpreted: if the assay is essential, stop the pill for at least 3 months (other contraception in the meantime).
Also consider
- Hyperandrogenism or irregular cycles? In a woman with hyperandrogenism or cycle disorders, see also the Hirsutism page.
Do not order
- Insulin or insulin resistance index in PCOS: of little clinical value, not recommended in routine practice [6].
Sudden, extensive or late-onset form: look for cancer
Tests
- No dedicated biological marker: the search for the associated cancer relies on clinical examination and imaging, directed first at the stomach.
Sources (10)
- Phiske MM. An approach to acanthosis nigricans. Indian Dermatol Online J. 2014;5(3):239-49.
- Gillespie J, Roland-McGowan J, Diehl K, Latour E, et al. Is acanthosis nigricans a marker for metabolic syndrome? A systematic review. Am J Clin Dermatol. 2026;27(5):945-957.
- Assurance maladie. Nomenclature des actes de biologie médicale (NABM), version 105 : actes 1577 (HbA1c), 1802 (SDHEA), 0358 (SHBG), 7422 (insuline).
- Radu AM, Carsote M, Dumitrascu MC, Sandru F. Acanthosis nigricans: pointer of endocrine entities. Diagnostics (Basel). 2022;12(10):2519.
- Popa ML, Popa AC, Tanase C, Gheorghisan-Galateanu AA. Acanthosis nigricans: to be or not to be afraid. Oncol Lett. 2019;17(5):4133-4138.
- Teede HJ, Tay CT, Laven J, Dokras A, Moran LJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Hum Reprod. 2023;38(9):1655-1679.
- American Diabetes Association Professional Practice Committee for Diabetes. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S27-S49.
- National Institute for Health and Care Excellence (NICE). Type 2 diabetes: prevention in people at high risk. Public health guideline PH38, publiée le 12 juillet 2012, mise à jour le 15 septembre 2017 (recommandations sur l'évaluation du risque et les tests sanguins).
- US Preventive Services Task Force. Prediabetes and Type 2 Diabetes: Screening. Final Recommendation Statement, 24 août 2021 (recommandation B).
- Grob JJ, Rava MC, Gouvernet J, et al. The relation between seborrheic keratoses and malignant solid tumours. A case-control study. Acta Derm Venereol 1991;71(2):166-9.