Prematurity-associated nephrocalcinosis and kidney function in early childhood

To assess the impact of prematurity-associated nephrocalcinosis on kidney f unction; later in life, 20 premature children with neonatal nephrocalcinosi s and 20 controls, matched for birth weight and postnatal age but without n ephrocalcinosis, were examined (birth weight 905+/-209 vs. 957+/-226 g; stu dy age 4.7+/-1.1 vs. 4.6+/-0.9 years). Distal tubular acidification capacit y was measured with the oral acetazolamide test, in which the response was abnormal in 1 out of the 20 children with a history of nephrocalcinosis, bu t in none of the controls. Urinary calcium and beta(2)-microglobulin excret ion were higher in the children with nephrocalcinosis, but no differences w ere found in fractional excretion of sodium and potassium or tubular reabso rption of phosphate. Estimated creatinine clearance was not different betwe en the groups. Of the 6 children with nephrocalcinosis lasting beyond 2 yea rs of age, 5 had had chronic lung disease neonatally and exhibited a tenden cy for compensated respiratory acidosis at the time of the examination. Neo natal nephrocalcinosis seems to lead to some signs of renal tubular dysfunc tion in early childhood of preterm infants. Glomerular function, however, a ppears not to be specifically disturbed by nephrocalcinosis.