HYPERCALCIURIA IN OSTEOGENESIS IMPERFECTA - A FOLLOW-UP-STUDY TO ASSESS RENAL EFFECTS

In 1991, we reported that hypercalciuria is a common finding in our pe diatric patient population with osteogenesis imperfecta (OI) (17 of 47 = 36%). Here, we prospectively screened 12 of these hypercalciuric ch ildren, on average 4 years subsequent to the discovery of elevated uri ne calcium levels, for adverse effects on renal function, Despite an a d libitum decrease since initial investigation of about 30% in their p reviously normal dietary calcium intake (adjusted for body weight), 8 of the 12 patients remained hypercalciuric (urine calcium/creatinine > 0.62 mmol/mmol). We found, once again, that urinary calcium levels si gnificantly correlated with the severity of the skeletal disease as as sessed by z-score for height (r = -0.75, p = 0.005). Evaluation of kid ney function, however, revealed: (i) normal routine urinalysis in all but 1 subject who had transient microscopic hematuria; (ii) unremarkab le concentrating ability determined by fasting urine osmolality; (iii) normal creatinine clearance, and (iv) unremarkable ultrasonography to measure renal size and to screen for nephrocalcinosis or nepthrolithi asis. Although no significant renal compromise was detected with these studies in our hypercalciuric pediatric OI patients, investigation of affected adults, especially those severely affected, will be importan t to assess whether this is a Long-term problem and if adverse effects on the kidneys do develop.