title: Longitudinal assessment of renal size and function in extremely low birth weight children at 7 and 11 years of age.
abstract: There are a lack of studies describing a longitudinal association between preterm delivery and renal complications later in life. We assessed renal size and function in preterm infants born with extremely low birth weight (ELBW) during 4 years of follow-up, comparing these parameters to age-matched children born full term (term controls).
  
  
  
  The results of selected renal laboratory tests [levels of cystatin C, creatinine, blood urea nitrogen (BUN)] and of renal ultrasound evaluations were compared between the ELBW group and the term control group at age 7 and 11 years.
  
  
  
  The study population consisted of 64 children born with ELBW (ELBW children) who had been recruited at birth and 36 children born at term (term children) who took part in both follow-up assessments. Renal ultrasound examination revealed a significantly smaller renal volume in the 7- and 11-year-old ELBW children compared to the term controls [right kidney volume: 50.8 vs. 61.2 ml/m(2), respectively, at 7 years (p <0.01) and 51.4 vs. 58.2 ml/m(2), respectively, at 11 years (p <0.01); left kidney volume: 51.4 vs. 60.3 ml/m(2), respectively, at 7 years (p <0.01) and 55.2 vs. 60.7 ml/m(2), respectively, at 11 years (p = 0.02)]. Renal function in ELBW children was also affected. Serum cystatin C levels were significantly higher in ELBW children than in the controls at 7 years of age, and this difference remained statistically significant at 11 years of age [0.63 vs. 0.59 mg/l, respectively, at 7 years (p = 0.02) and 0.72 vs. 0.61 mg/l, respectively, at 11 years (p = 0.01)]. Six ELBW children also had elevated cystatin C levels (0.97-1.11 mg/l) at 11 years of age. Cystatin C levels were within normal range in the ELBW children at age 7 years and in term children in both follow-up studies. BUN levels were higher in ELBW children at the age of 11 years (4.49 vs. 4.15 mmol/l; p = 0.028).
  
  
  
  Continued follow-up of these patients will reveal whether the observed worsening in renal function will persist into adulthood.
authors.affiliation: Department of Pediatrics, Jagiellonian University Medical College, Wielicka Street 265, Cracow, 30-663, Poland. ka.starzec@gmail.com.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Starzec
authors.affiliation: Department of Pediatrics, Jagiellonian University Medical College, Wielicka Street 265, Cracow, 30-663, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Klimek
authors.affiliation: Department of Pediatrics, Jagiellonian University Medical College, Wielicka Street 265, Cracow, 30-663, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Grudzień
authors.affiliation: Department of Pediatrics, Jagiellonian University Medical College, Wielicka Street 265, Cracow, 30-663, Poland.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Jagła
authors.affiliation: Department of Pediatrics, Jagiellonian University Medical College, Wielicka Street 265, Cracow, 30-663, Poland.
authors.forename: Przemko
authors.initials: P
authors.lastname: Kwinta
mesh_terms: D001724:Birth Weight / Q000502:physiology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D052577:Infant, Extremely Low Birth Weight / Q000502:physiology*; D062071:Infant, Extremely Premature / Q000502:physiology*; D007231:Infant, Newborn; D007668:Kidney / Q000000981:diagnostic imaging / Q000502:physiology*; D007677:Kidney Function Tests; D008137:Longitudinal Studies; D008297:Male; D009929:Organ Size / Q000502:physiology; D012307:Risk Factors; D014463:Ultrasonography; D018615:Ultrasonography, Doppler, Color
keywords: Cystain C; ELBW; Preterm infants; Renal complications; Renal function; Renal ultrasound; Renal volume; eGFR