18 - Association of Gestational Age, Birthweight, and Growth Restriction with Baseline Kidney Function in Youth with Primary Hypertension

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 18
Publication Number: 18.322

Carol Vincent, Wake Forest Baptist Health - Brenner Children's Hospital, Summerfield, NC, United States; Ashton Chen, Wake Forest University School of Medicine, Winston-Salem, NC, United States; Andrew M.. South, Wake Forest School of Medicine of Wake Forest Baptist Medical Center, Winston Salem, NC, United States

Presenting Author(s)

Carol Vincent, MD (she/her/hers)

pediatric nephrology fellow
Wake Forest Baptist Health - Brenner Children's Hospital
Winston Salem, North Carolina, United States

Background: Individuals born preterm are vulnerable to hypertension (HTN) and chronic kidney disease (CKD) throughout their lifetime. Preterm birth is associated with lower nephron mass and worse vascular reactivity that may alter susceptibility to kidney target organ injury (TOI) from HTN. Low birthweight (BW) and growth restriction are also risk factors for non-communicable chronic disease later in life, but the mechanism and interplay between risk factors are not well understood.

Objective: To determine the association of gestational age (GA), BW, and BW z-score with urine albumin-to-creatinine (UACR) ratio, urine protein-to-creatinine ratio (UPCR), serum creatinine, and estimated glomerular filtration rate (eGFR) in youth with primary HTN.

Design/Methods: This is a secondary analysis of baseline data from a pilot prospective cohort study of youth aged 5–17 years with newly diagnosed primary HTN per AAP Clinical Practice Guideline criteria. Exclusion criteria were secondary HTN, diabetes, heart disease or CKD. Early-life data were obtained by parental report, including GA, BW, and maternal pregnancy complications (pre-eclampsia or diabetes). Exposures were GA, preterm birth (GA < 37 weeks), BW, low BW (< 2.5 kg), BW z-scores, and small for GA status (SGA, BW < 10^th %ile for GA and sex). Outcomes were UACR (ln-UACR), UPCR, serum creatinine, and eGFR. We estimated associations between exposures and outcomes using generalized linear models adjusted for maternal pregnancy complications.

Results:

Of the 30 participants, median GA was 39 weeks [IQR 36, 40] with 27% born preterm (Table 1). No participants had a UPCR ≥0.2 mg/mg. There were 4 participants with UACR ≥30 mg/g who were all term with BW ≥2.5 kg. In adjusted analyses, preterm birth was significantly associated with lower UPCR and UACR and low BW was associated with lower ln-UACR. Lower BW and BW z-score were associated with lower eGFR but only by original, not modified, Schwartz equation (Table 2).

Conclusion(s): Early-life risk factors were associated with modest changes in baseline kidney function in youth with primary HTN, specifically less proteinuria but lower eGFR by one of two measures. Youth with and without early life risk factors may not have differential susceptibility to HTN-associated kidney TOI or it may be too early in the disease course to see a difference. Our study was a pilot study and therefore limited by sample size. Future directions include investigating differential biochemical contributions in kidney and cardiac TOI associated with HTN, as the mechanism and timing may be different in longer-term follow-up.