Effect of diuretics on urinary oxalate, calcium, and sodium excretion in very low birth weight infants.

OBJECTIVE

To study the effect of diuretic drugs on urinary oxalate excretion in premature infants, and to examine the relationship between urinary calcium and sodium excretion in premature infants.

METHODOLOGY

We measured urinary oxalate, calcium, and sodium excretion in 32 premature infants at approximately 34 weeks gestational age. Seven infants were receiving furosemide, 5 infants were receiving thiazide, 8 infants were receiving furosemide plus thiazide, and 12 infants who were not receiving diuretics served as controls.

RESULTS

Urinary oxalate to creatinine ratios in infants receiving furosemide (0.48 +/- .26), thiazide (0.54 +/- .20), furosemide plus thiazide (0.44 +/- .19), and control infants (0.51 +/- .43) were similar by analysis of variance (ANOVA). Data expressed as oxalate concentration gave similar results. Urinary calcium to creatinine ratios in infants receiving furosemide (0.81 +/- .30), thiazide (0.54 +/- .25), furosemide plus thiazide (0.75 +/- .49), and control infants (0.37 +/- .25) were similar by ANOVA. The urinary calcium concentration in infants receiving furosemide plus thiazide (0.085 +/- 0.042 mg/mL) was different from control infants (0.044 +/- .023) by ANOVA and Student-Newman-Keuls test. Urinary calcium to creatinine ratio was correlated with sodium to creatinine ratio (r = .751).

CONCLUSION

Urinary oxalate excretion in premature infants is not affected by diuretic drugs. Urinary sodium and calcium excretion are closely linked in sodium supplemented premature infants receiving diuretics. The calciuric effect of furosemide is not decreased by the addition of thiazide in premature infants receiving sodium supplements.