Abstract 100

Aims:- To study incidence of and aetiological factors in nephrocalcinosis in babies born < than 1.5kgs or < 32 weeks gestation.

Subjects:- Babies of birth weight < 1.5kgs or gestation < 32 weeks were eligible. Two renal ultrasound scans were performed, the first at 1 month postnatal age, the 2nd at term or discharge. Incidence of oliguria on day 1 and use of phosphate supplements, diuretics, dexamethasone and nephrotoxic antibiotics was noted and urinary calcium/creatinine ratio measured at discharge or term.

Results:- 77 patients have completed the study. Abnormalities on renal ultra-sound were noted in 18 (23.3%). There were 11 cases of nephrocalcinosis (14.2%). Other renal abnormalities detected on ultra-sound were hydronephrosis in 4, renal stone in 1, bifid pelvis in 1 and an absent kidney in 1. Mean gestation of babies was 29.2 weeks (range 24 - 34) weeks. Mean birth weight 1.23kgs (range 0.56 to 2.7kgs). Babies with nephrocalcinosis had a lower mean gestation (27.7 weeks) and birth weight (1.1kgs). No baby with nephrocalcinosis had oliguria on day 1, but 6 (54.5%) had been treated with furusemide. 8 babies with nephrocalcinosis (72.7%) had high levels of nephrotoxic antibiotics during their clinical course and 8 (72.7%) were oxygen dependent at 36 weeks. 6 (54.5%) had been treated with dexamethasone postnatally. Only 3 (27.2%) had elevated urinary calcium/creatinine ratios.

Conclusion:- A significant number of babies born < 32 weeks gestation have nephrocalcinosis. Oxygen dependence at 36 weeks post conception and furusemide are risk factors.