Kidney volume, kidney function, and ambulatory blood pressure in children born extremely preterm with and without nephrocalcinosis

• Published in: Pediatric nephrology (Berlin, West) Vol. 34; no. 10; pp. 1765 - 1776
• Main Authors: Rakow, Alexander, Laestadius, Åsa, Liliemark, Ulrika, Backheden, Magnus, Legnevall, Lena, Kaiser, Sylvie, Vanpée, Mireille
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-10-2019; Springer; Springer Nature B.V
• Subjects: Age; Blood pressure; Calcinosis; Children; Circadian rhythms; Control; Cystatin C; End-stage renal disease; Gestational age; Glomerular filtration rate; Hypertension; Infants; Kidney diseases; Kidneys; Medicin och hälsovetenskap; Medicine; Medicine & Public Health; Neonates; Nephrology; Original; Original Article; Pediatrics; Renal function; Risk factors; Ultrasound; Urine; Urology; What’s new in Renal Development; Circadian regulation; Nephrocalcinosis; Blood pressure; Kidney volume; Renal function; Preterm
• ISSN: 0931-041X; 1432-198X; 1432-198X
• DOI: 10.1007/s00467-019-04293-9

Background
Reduced kidney volume (KV) following prematurity is a proxy for reduced nephron number and is associated with the development of hypertension and end-stage renal disease in adults. We investigated whether extreme prematurity affects KV, function, and blood pressure in school-aged children and if nephrocalcinosis (NC) developed during the neonatal period had additional effects.
Methods
We investigated 60 children at a mean age of 7.7 years: 20 born extremely preterm (EPT < 28 weeks gestational age with NC (NC+)), 20 born EPT without NC (NC−), and 19 born as full-term infants (control). We measured KV by ultrasound, collected blood and urine samples to evaluate renal function, and measured office and 24-h ambulatory blood pressure (ABPM).
Results
Children born EPT had significantly smaller kidneys (EPT (NC+ NC−) vs control (estimated difference, 11.8 (CI − 21.51 to − 2.09 ml),
p
 = 0.018) and lower but normal cystatin C–based glomerular filtration rate compared with control (estimated difference, − 10.11 (CI − 0.69 to − 19.5),
p
 = 0.035). KV and function were not different between NC+ and NC− groups. Change in KV in relation to BSA (KV/BSA) from the neonatal period to school age showed significantly more EPT children with neonatal NC having a negative evolution of KV (
p
 = 0.01). Blood pressure was normal and not different between the 3 groups. Fifty percent of EPT had a less than 10% day-to-night decline in ABPM.
Conclusions
Kidney growth and volume is affected by EPT birth with NC being a potential aggravating factor. Circadian blood pressure regulation seems abnormal in EPT-born children.