Article of the Month - Jan 2021

Albuminuria, Hypertension, and Reduced Kidney Volumes in Adolescents Born Extremely Premature

Front Pediatr. 2020 May 12;8:230. doi: 10.3389/fped.2020.00230

Keia R. Sanderson, Emily Chang, Erica Bjornstad, Susan L. Hogan, Yichun Hu, David Askenazi, Rebecca C. Fry and T. Michael O'Shea

Reviewed by Catherine Joseph

Background:

Premature birth is associated with decreased nephron number and an increased risk for chronic kidney disease (CKD). Despite the higher risk of CKD in infants born preterm, evidence based consensus guidelines have not been developed for kidney follow up after discharge from NICU.

What was the purpose of the research?

In order to help develop guidelines for kidney follow up in premature infants, the authors studied a group of individuals born extremely preterm [<28 weeks GA] to characterize the prevalence and predictors of microalbuminuria, elevated blood pressure and/or reduced kidney volume in adolescence.

What were the study design and methods?

This was a prospective cohort study. The subjects for this study were a subset of participants [n=42] enrolled at birth in the Extremely Low Gestational Age Newborns (ELGAN) study. ELGAN is a multicenter prospective observational study of infants before 28 weeks gestation between April 2002 and August 2004. Neonatal characteristics in relation to kidney injury were also abstracted from ELGAN database.

When participants from the study turned 15 years old at a single center, authors obtained 2 manual blood pressures, a spot urine micro albumin measurement, and sonographic measurements of kidney length and volume. 

What were the results of this study?

Of the 42 participants, 60% were male, median age was 15 years.

  • In 33.3% of the cohort, blood pressure was elevated (>120/80 mmHg).
  • 11.9% of the cohort had microalbuminuria (>30 mg/g)  
  • 14% had kidney volume below the 10th percentile of normative data.
  • Twenty-one (50%) of the sample had at least one kidney abnormality (microalbuminuria, elevated blood pressures, and/or kidney hypoplasia)
  • These individuals were more likely to have experienced neonatal hypotension [55% vs. 17% among those with no kidney abnormality, p = 0.02]. 

The strengths of the study includes a cohort selected based on gestation age and the use of non-invasive markers that are predictive of progression of CKD. The study is limited by small sample size and lack of serum creatinine or Cystatin C data.

What was the conclusion?

Half of adolescents in this subset of ELGAN cohort have at least one risk factor of kidney disease (reduced kidney volume, microalbuminuria, and/or elevated blood pressures) at 15 years of age.

Why does this matter?

Children born prematurely are at higher risk of developing kidney disease during adolescence. This study lays the framework for designing larger studies that could possibly replicate and/or add to the findings of the current study. This could provide greater evidence to design guidelines for kidney follow up in this vulnerable population.