CARDIOVASCULAR-ABNORMALITIES IN PATIENTS WITH X-LINKED HYPOPHOSPHATEMIA

Treatment for X-linked hypophosphatemia (XLH; vitamin D metabolites an d phosphate salts) may result in hypercalcemia, hypercalciuria, nephro calcinosis, and hyperparathyroidism. Cardiovascular abnormalities occu r in association with these complications, but have not been reported in XLH. We hypothesized that such abnormalities may occur in XLH and e valuated cardiovascular status in 13 patients with this disease. All p atients were asymptomatic and had normal cardiovascular physical exami nations and Holter studies. Serum calcium and creatinine clearance wer e normal in all. However, all patients had mild to moderate nephrocalc inosis. Left ventricular hypertrophy was diagnosed by electrocardiogra m in three and by ultrasonography in seven children. Baseline blood pr essure (BP) was normal (mean +/- SD, +/- 15/74 +/- 6 mm Hg). During ex ercise stress testing, systolic BP increased in all patients, but the maximal systolic pressure was less than that in healthy age- and sex-m atched controls (156 +/- 20 vs. 175 +/- 23; P = 0.002, by t test). An abnormal increase in diastolic BP occurred at all levels of work load in XLH patients; their peak exercise diastolic BP was 91 +/- 12 cs. 72 +/- 6 mm Hg in controls (P < 0.0001, by t test). Whether these abnorm al findings are primaly defects in XLH or represent complications of t reatment is unclear. Patients with XLH should be monitored closely for the development of hypertension and left ventricular hypertrophy. Inv estigation of the mechanisms involved and establishment of therapeutic guidelines are indicated.