Acute changes in fluid status affect the incidence, associative clinical outcomes, and urine biomarker performance in premature infants with acute kidney injury

Pediatr Nephrol. 2016 May;31(5):843-51. doi: 10.1007/s00467-015-3258-4. Epub 2015 Nov 16.


Background: During the first postnatal weeks, infants have abrupt changes in fluid weight that alter serum creatinine (SCr) concentration, and possibly, the evaluation for acute kidney injury (AKI).

Methods: We performed a prospective study on 122 premature infants to determine how fluid adjustment (FA) to SCr alters the incidence of AKI, demographics, outcomes, and performance of candidate urine biomarkers. FA-SCr values were estimated using changes in total body water (TBW) from birth; FA-SCR = SCr × [TBW + (current wt. - BW)]/ TBW; where TBW = 0.8 × wt in kg). SCr-AKI and FA-SCr AKI were defined if values increased by ≥ 0.3 mg/dl from previous lowest value.

Results: AKI incidence was lower using the FA-SCr vs. SCr definition [(23/122 (18.8 %) vs. (34/122 (27.9 %); p < 0.05)], with concordance in 105/122 (86 %) and discordance in 17/122 (14 %). Discordant subjects tended to have similar demographics and outcomes to those who were negative by both definitions. Candidate urine AKI biomarkers performed better under the FA-SCr than SCr definition, especially on day 4 and days 12-14.

Conclusions: Adjusting SCr for acute change in fluid weight may help differentiate SCr rise from true change in renal function from acute concentration due to abrupt weight change.

Keywords: Creatinine; Definitions; Fluid adjustment; NGAL; Urinary biomarkers; Very low birth weight.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Kidney Injury / diagnosis*
  • Acute Kidney Injury / epidemiology
  • Acute Kidney Injury / physiopathology
  • Acute Kidney Injury / therapy
  • Alabama / epidemiology
  • Biomarkers / blood
  • Biomarkers / urine
  • Birth Weight
  • Creatinine / blood
  • Gestational Age
  • Humans
  • Incidence
  • Infant, Newborn
  • Infant, Premature*
  • Infant, Very Low Birth Weight
  • Kidney / physiopathology*
  • Models, Biological
  • Predictive Value of Tests
  • Prospective Studies
  • Reproducibility of Results
  • Time Factors
  • Urinalysis
  • Water-Electrolyte Balance*
  • Water-Electrolyte Imbalance / diagnosis*
  • Water-Electrolyte Imbalance / epidemiology
  • Water-Electrolyte Imbalance / physiopathology
  • Water-Electrolyte Imbalance / therapy
  • Weight Loss


  • Biomarkers
  • Creatinine