Renal calcification in preterm infants: follow up at 4-5 years

Abstract

Aim-To determine the consequences of renal calcification in preterm infants. Methods-A cohort of 11 preterm babies was studied at the age of 4 to 5 years. They had had renal calcification as neonates. Seventeen matched controls were also studied. Each child had a renal ultrasound scan, a calcium load test, and a desmopressin test for renal concentrating ability (RCA). The study group also had glomerular filtration rate (GFR) estimated, using the height:creatinine ratio, and tubular phosphate reabsorption, without phosphate load, per glomerular filtration rate (Tp/GFR) calculated. Results-In the study group the median GFR was 61 ml/min/1.73m 2 (range 46-79 ml/min/1.73m2 ) and the median calculated Tp/GFR SD score was −0.94 (range −2.8-0.68). Five children out of the study group had ultrasonic evidence of renal calcification. There was no significant diVerence between the two groups in renal size, calciuria, before or after calcium load, or RCA. Eight children (three patients, five controls) had an abnormal calcium load test. The RCA of the children in the study and control groups combined was below that of published values, with a median calculated SD score −0.71 (95% CI −1.21 to −0.23). Conclusions-There was evidence of renal dysfunction in children who had been born preterm. Renal calcification detected in the neonatal period does not seem to be a major predisposing factor for the abnormalities of renal function subsequently observed in these infants. (Arch Dis Child 1997;76:F185-F189)

Salt Sensitivity of Children With Low Birth Weight

“…34 If renal damage, such as calcifications, was overt early after birth, then reduced renal function persisted. 35 Two studies of subjects born with LBW, with and without further indication of SGA, found normal renal function at the age of 20 to 30 years. 36,37 Very convincing evidence for the long-term impact of LBW on kidney survival was given in an epidemiological study that showed an increased risk of developing chronic kidney disease stage 5 in those adults born as growthrestricted children.…”

Nephrocalcinosis in preterm neonates

“…Jones et al studied 11 former preterms when they were aged 4-5 years with neonatal NC. They found low median TmP/GFR (tubular maximum of phosphate reabsorption corrected for glomerular filtration rate) in comparison with reference values [71]. Likewise, Saarela et al observed a significantly higher urine β 2 -microglobulin/creatinine ratio in 20 children with NC than in 20 children without NC as preterm neonates, when they were a mean age of 4.7 years.…”

“…On the other hand, two studies demonstrated early morning urine osmolality to be significantly lower in former preterms than in healthy children [6,71]. However, test results indicating impaired concentrating ability after desmopressin was found in 4/30 children with neonatal NC at 1 year and in 2/25 at 2 years [70].…”

“…However, persistence for several years has been described [11,14,69,[71][72][73][74]. In the largest ongoing study of preterm neonates, NC persisted in 34%, 15% and 10% after 15 months, 30 months and 7.4 (±1.0) years, respectively (Fig.…”

“…Several (early) studies comprising a limited number of selected children with preterm NC demonstrated reduced glomerular filtration rate (GFR) when they were aged between 1 year and 5 years [69,71,72]. In a prospective follow-up study, after 7.4±1 years, significantly more children with NC (6/40, 15%) had low GFR (<85 ml/min per 1.73 m 2 body surface area) than did healthy children, this in contrast to children without neonatal NC (2/32, 6%), Fig.…”