X-Linked Hypophosphatemia: Progress in Characterization of Genetic and Metabolic Defects

Autonomous hyperparathyroidism in X‐linked hypophosphataemia

“…It is possible that hypophosphataemic rickets in humans encompasses more than one genetic defect analogous to the two loci in the mouse (Kainer et al, 1989). Although unlikely, it cannot be excluded that the patients in the present study are part of a specific 'Nordic' genetic variant prone to develop autonomous hyperparathyroidism.…”

“…Secondly, the concomitant defect in vitamin D metabolism andlor action in hypophosphataemic rickets result in decreased vitamin D induced inhibition of PTH secretion, and it has been shown that hyperparathyroidism may be normalized after treatment with la-hydroxyvitamin D3 (Rasmussen et al, 1981). Thirdly, phosphate treatment may result in reduced levels of vitamin D and calcium, and with secondary stimulation of PTH secretion (Firth et al, 1985;Reid et al, 1989), as indicated by the development of reversible hyperparathyroidism in patients treated with phosphate but not with vitamin D (Alon et al, 1984;Glorieux et al, 1972;Hanna ef al., 1991;Kainer et a!., 1989). Similarly, hyperparathyroidism has been reported during long-term phosphate supplementation in hypophosphataemic osteomalacia (Firth et al, 1985;Reid et al, 1987).…”

“…The optimal treatment regimen in X-linked hypophosphataemic rickets has not yet been established (Glorieux, 1991). Although the disease possibly may be left untreated (Stickler & Morgenstern, 1989), treatment with vitamin D results in healing of the bone lesions, and phosphate therapy also contributes to a better mineralization and improvement of growth velocity (Kainer et al, 1989;Hanna et al, 1991). However, treatment with vitamin D and phosphate must be balanced in order to avoid hypercalcaemia and hyperparathyroidism, respectively (Glorieux et al, 1972;Rasmussen et al, 1981;Verge et al, 1991).…”