Keratin-based hair straightening treatment is a popular hair styling method. The majority of these products in Israel contain glycolic acid derivatives, which are considered safe when used topically. Systemic absorption of these products is possible and anecdotal reports have described kidney toxicity associated with their use. We report a series of cases of severe AKI following use of hair-straightening treatment occurring in Israel over the past several years.Case series.We retrospectively identified 26 patients from 14 medical centers in Israel who developed severe AKI and reported prior treatment with hair-straightening products between 2019 and 2022.The 26 patients described had a median age of 28.5 years (range, 14-58) and developed severe AKI following hair-straightening procedure. The most common symptoms at presentation were nausea, vomiting, and abdominal pain. Scalp rash was noted in 10 (38%) patients. Two patients developed a recurrent episode of AKI following a repeat hair-straightening treatment. Seven patients underwent kidney biopsies that demonstrated intra-tubular calcium oxalate deposition in six and microcalcification in tubular cells in one. In all biopsies, signs of acute tubular injury were present, and an interstitial infiltrate was noted in four cases. Three patients required temporary dialysis.Retrospective uncontrolled study, small number of kidney biopsies.This study describes cases of acute kidney injury with prior exposure to hair straightening treatments. Acute oxalate nephropathy was the dominant finding on kidney biopsies, which may be related to absorption of glycolic acid derivatives and their metabolism to oxalate. This case series suggests a potential under-recognized cause of AKI in the young healthy population. Further studies are needed to confirm this association and to assess the extent of this phenomenon as well as its pathogenesis.
