Indications for the evaluation and supplementation of hypophosphatemia: an umbrella systematic review of reviews and guidelines.

BACKGROUND: Hypophosphatemia, defined as low serum phosphate levels, is a frequent yet underrecognized condition associated with significant morbidity. Its etiology ranges from chronic conditions such as osteomalacia to acute states such as refeeding syndrome. This review systematically summarizes evidence and guidelines for phosphate testing and supplementation in adults, aiming to support clinical decision-making. METHODS: We conducted a systematic review following the PRISMA guidelines. Searches of MEDLINE, Embase, the Cochrane Library, and Google Scholar from inception to September 2024 included reviews, guidelines, and consensus statements addressing phosphate measurement for hypophosphatemia and supplementation in adults outside intensive care settings. Eligibility criteria included English-language publications focused on diagnostic and therapeutic recommendations. Quality assessment was performed using the AGREE II tool, and data were synthesized across chronic and acute clinical contexts. RESULTS: Thirty-three publications (11 guidelines, 19 reviews, and 3 consensus statements) were included, with high heterogeneity in the recommendations. Phosphate measurement to evaluate chronic hypophosphatemia is recommended for persistent musculoskeletal symptoms, osteoporosis evaluation, and rare conditions known to cause chronic hypophosphatemia, such as X-linked hypophosphatemia and tumor-induced osteomalacia. The post-kidney transplantation stage requires intensive early monitoring for hypophosphatemia. Recommendations for testing for drug-induced hypophosphatemia, such as with ferric carboxymaltose, vary. Phosphate measurement to evaluate acute hypophosphatemia is advised in high-risk settings: refeeding syndrome, hyperglycemic hyperosmolar syndrome, alcoholic ketoacidosis, worsening COPD or asthma exacerbations. Further potential indications for phosphate measurement include certain iron infusions, tenofovir treatment, immediate post-kidney transplantation, and intensive hemodialysis. Supplementation is indicated for severe or symptomatic cases, with oral therapy preferred for chronic conditions and intravenous routes for acute, severe hypophosphatemia. CONCLUSIONS: The heterogeneity in the recommendations emphasizes the need for individualized approaches based on clinical context. While robust evidence supports testing and supplementation under select conditions, gaps remain regarding optimal dosing and monitoring protocols. Clinicians should consider phosphate testing in high-risk scenarios and follow evidence-based supplementation guidelines tailored to chronic and acute hypophosphatemia. Future research is needed to unify recommendations and address existing uncertainties.