Clinical aspects of X-linked hypophosphatemic rickets.

X-link hypophosphatemia (XLH) is the most common heritable form of rickets and is usually transmitted as an X-linked dominant disorder Until now there is no report about clinical data of XLH in Taiwan. We retrospectively studied 15 patients (5 males and 10 females) of XLH in our hospital in the past 18 years to delineate the clinical aspects of this disease. A total of 7 patients had family histories consistent with XLH; 8 appeared to be sporadic cases. Fourteen of 15 cases had typical physical and radiologic findings of rickets except case 1 who only had waddling gait and sacroiliitis with the initial complaint of joint pain. All 15 cases had normal serum creatinine, normocalcemia, normal 1,25-dihydroxyvitamin D (1,25-(OH)2D), reduced serum phosphate concentration, reduced urinary calcium excretion and reduced TmP/GFR. All but one had reduced %TRP. Thirteen of 15 cases had elevated alkaline phosphatase activity; two showed hyperparathyroidism. Four cases had sufficient follow-up growth data and had an increase in height percentile and velocity after combination therapy.