Sammanfattning
Fibroblast growth factor 23 (FGF23) is a recently identified phosphatonin. Its main physiological functions are to maintain serum phosphate within its reference range and to counter regulate the effects of vitamin D. Diseases correlated to high serum values of FGF23 are hypophosphatemic rickets, fibrous dysplasia, and tumour-induced osteomalacia. In contrast, hyperphosphatemic tumoral calcinosis is associated with accelerated degradation of FGF23. Measuring FGF23 serves as a differential diagnostic tool in elucidating conditions of long-lasting hypophosphatemia.