ESPE Abstracts

Background: Hypophosphatemic rickets is a clinical picture with inadequate bone mineralization that develops following renal phosphate loss. One of the most common complications in this group of patients is nephrocalcinosis. However, the mechanisms causing nephrocalcinosis are not clear.

Objective and hypotheses: The aim of our study was to define the risk factors affecting the development of nephrocalcinosis, which is reported to be seen at a rate of 50% in this patient group, and to enable preventive measures to be taken.

Method: A total of six patients diagnosed with hypophosphatemic rickets at Dr Sami Ulus Training and Research Hospital and then followed up for at least 3 years were included in the study. The patients were evaluated at 3-month periods. Serum calcium, phosphorus, alkaline phosphatase, bicarbonate, creatinine, BUN, PTH, and spot urine Ca/cr ratios were recorded. Renal and urinary system ultrasonography was performed at the beginning and then at 6-month intervals. The patients were treated with calcitriol and phosphate supplementation.

Results: Nephrocalcinosis developed in three of the six cases with at least 3 years (range 36–60 months) of follow-up. The mean phosphate dose was higher in the group that developed nephrocalcinosis than the group without nephrocalcinosis (P<0.05). The calcitriol dose was also higher in the nephrocalcinosis group but the difference between the two groups was not significant (P>0.05). There was no relationship between the hypercalcemia and hypercalciuria episodes detected in the two groups and nephrocalcinosis development (P>0.05).

Conclusion: A high phosphate dose is generally seen as a risk factor for nephrocalcinosis (P<0.05). We had four cases consisting of two groups of siblings. The fact that only one sibling developed nephrocalcinosis in both these sibling groups indicates that the treatment agents used are more effective than genetic factors in these patients. However, new studies with a larger number of patients are needed to enable more definite conclusions on this issue.