Is nephrocalcinosis in preterm neonates harmful for long-term blood pressure and renal function?
OBJECTIVE
The aim of our study was to examine long-term effects of nephrocalcinosis in prematurely born children.


METHODS
Preterm neonates (gestational age <32 weeks) with (n = 42) and without (n = 32) nephrocalcinosis were prospectively studied at a mean age of 7.5 (+/-1.0) years.


RESULTS
Blood pressure did not differ in ex-preterm infants with and without nephrocalcinosis but was significantly higher than expected for healthy children. In comparison to healthy children, more ex-preterm infants with neonatal nephrocalcinosis had (mild) chronic renal insufficiency (glomerular filtration rate: <85 mL/min per 1.73 m2; 6 of 40); this is in contrast to ex-preterm infants without neonatal nephrocalcinosis (2 of 32). Tubular phosphate reabsorption and plasma bicarbonate were significantly lower in children with nephrocalcinosis compared with children without nephrocalcinosis. In addition, more ex-preterm infants with and without nephrocalcinosis than expected had low values for plasma bicarbonate and early-morning urine osmolality compared with healthy children. Kidney length of ex-preterm infants with and without nephrocalcinosis was significantly smaller than expected in healthy children of the same height. Nephrocalcinosis persisted long-term in 4 of 42 children but was not related to blood pressure, kidney length, or renal function.


CONCLUSIONS
Nephrocalcinosis in preterm neonates can have long-term sequelae for glomerular and tubular function. Furthermore, prematurity per se is associated with high blood pressure, relatively small kidneys, and (distal) tubular dysfunction. Long-term follow-up of blood pressure and renal glomerular and tubular function of preterm neonates, especially with neonatal nephrocalcinosis, seems warranted.
Kist-van Holthe
Joana E
JE
Department of Pediatrics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands. j.kist@lumc.nl
van Zwieten
Paul H T
PH
Schell-Feith
Eveline A
EA
Zonderland
Harmien M
HM
Holscher
Herma C
HC
Wolterbeek
Ron
R
Veen
Sylvia
S
Frolich
Marijke
M
van der Heijden
Bert J
BJ
D001794:Blood Pressure; D002118:Calcium / Q000652:urine; D002648:Child; D002657:Child Development; D019343:Citric Acid / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007668:Kidney / Q000000981:diagnostic imaging / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D009397:Nephrocalcinosis / Q000150:complications / Q000503:physiopathology*; D009929:Organ Size; D011446:Prospective Studies; D012016:Reference Values; D051437:Renal Insufficiency / Q000209:etiology / Q000652:urine; D014463:Ultrasonography
D019343:Citric Acid; D002118:Calcium