Urinary β2-microglobulin and bronchopulmonary dysplasia: Trends in preterm infants

Gestational age, sex, and time affect urine biomarker concentrations in extremely low gestational age neonates

BACKGROUND

Our understanding of the normative concentrations of urine biomarkers in premature neonates is limited.

METHODS

We evaluated urine from 750 extremely low gestational age (GA) neonates without severe acute kidney injury (AKI) to determine how GA affects ten different urine biomarkers at birth and over the first 30 postnatal days. Then, we investigated if the urine biomarkers changed over time at 27, 30, and 34 weeks postmenstrual age (PMA). Next, we evaluated the impact of sex on urine biomarker concentrations at birth and over time. Finally, we evaluated if urine biomarkers were impacted by treatment with erythropoietin (Epo).

RESULTS

We found that all ten biomarker concentrations differ at birth by GA and that some urine biomarker concentrations increase, while others decrease over time. At 27 weeks PMA, 7/10 urine biomarkers differed by GA. By 30 weeks PMA, 5/10 differed, and by 34 weeks PMA, only osteopontin differed by GA. About half of the biomarker concentrations differed by sex, and 4/10 showed different rates of change over time between males vs. females. We found no differences in urine biomarkers by treatment group.

CONCLUSIONS

The temporal patterns, GA, and sex differences need to be considered in urine AKI biomarker analyses.

IMPACT

Urine biomarker concentrations differ by GA at birth. Some urine biomarkers increase, while others decrease, over the first 30 postnatal days. Most urine biomarkers differ by GA at 27 weeks PMA, but are similar by 34 weeks PMA. Some urine biomarkers vary by sex in premature neonates. Urine biomarkers did not differ between neonates randomized to placebo vs. Epo.

The Effect of Antenatal Steroid Therapy on Early Inflammation Markers and Leukocyte Counts in Premature Infants

ObjectiveWe investigated the effect of antenatal steroid therapy(AST) on white blood cell (WBC) and neutrophil counts and the inflammatory markers C-reactive protein(CRP), interleukin 6(IL-6), interleukin 10(IL-10), and beta-2 microglobulin(ß2M) in preterm infants.Materials MethodNeonates born at ≤34 weeks of gestation and admitted at hospital between May and November 2018 were included. The neonates were divided into three groups based on AST dose administered: 24 mg betamethasone (full course), 12 mg betamethasone (incomplete course), and no AST. 170 infants were analyzed.ResultsOf these, 45.2% (n = 77) received a full course of AST, 38.8% (n = 66) received an incomplete course of AST, and 15.8% (n = 27) did not receive AST. WBC, CRP, IL-6, IL-10, and ß2M levels were similar between the three groups, whereas neutrophil count was significantly lower in full course AST group.ConclusionConsistent with the literature data, AST was associated with reduced neutrophil count but did not affect the other inflammatory markers studied.