Emerging Risks: AKI Associated with Glyoxylic Acid Hair Straightening Products in Brazil

Introduction: Hair straightening products containing glyoxylic acid (instead of formaldehyde) have gained popularity in recent years. Thirty-one cases of acute kidney injury (AKI) due to the formation of intratubular calcium oxalate crystals associated with the use of these products have been reported. This is the first documented case of AKI associated with formaldehyde-free hair straightening in Brazil. Case Description: A 34-year-old, previously healthy Black woman developed abdominal pain, nausea, and vomiting within minutes of undergoing a hair straightening procedure at a beauty salon. She sought medical attention two days later due to persistent symptoms. Upon admission, serum creatinine levels were 11.5 mg/dL (baseline 0.85 mg/dL), blood urea nitrogen (BUN) was 46 mg/dL, and urinalysis revealed hematuria, leukocyturia, and eosinophiluria. Imaging studies were unremarkable. Immunologic and serologic workups were negative. Urinary oxalate excretion was elevated (45.5 mg/24 h), and renal biopsy revealed intratubular oxalate crystals, tubular hydropic degeneration, and peritubular eosinophils, without glomerular crescents. The patient received pulse methylprednisolone (1 g/day for 3 days) followed by oral prednisone (1 mg/kg/day). She exhibited rapid clinical and biochemical improvement and was discharged asymptomatic after 10 days, with a creatinine level of 1.5 mg/dL and outpatient follow-up scheduled. Three months later, the oxaluria and the eGFR were within normal limits. Discussion: This report presents the first documented case of AKI associated with the use of formaldehyde-free hair straighteners in Brazil, making it the thirty-second such case reported in the literature. Given that hair straightening is a common practice in the United States and these products are readily available for sale, it is crucial that the American medical community and regulatory agencies become aware of this emerging etiology of AKI. Reporting and disseminating such cases are essential for recognizing this serious, preventable, and treatable condition.