4 citations,
March 2020 in “JAAD Case Reports” Vitamin B12 deficiency can cause darkening of all nails.
November 2022 in “Indian Journal of Dermatology/Indian journal of dermatology” Valproic acid can cause dark lines on nails.
2 citations,
September 2014 in “Journal of evolution of medical and dental sciences” Most HIV patients in the study showed skin and mucous membrane issues, with oral thrush being the most common.
January 2014 in “Pathology” The document concludes that understanding nail anatomy is key for diagnosing nail diseases, early signs of nail melanoma may allow for less aggressive treatment, and specific genetic mutations are important in thyroid cancer prognosis and treatment.
October 2023 in “CRC Press eBooks” Children with darker skin can have various hair and nail issues.