Renal function and size at young adult age after intrauterine growth restriction and very premature birth

Background: Premature birth and intrauterine growth restriction may increase the risk of developing renal disease at adult age. Renal function may already be impaired at young adult age. Study Design: Cross-sectional study. Setting & Participants: Very premature individuals (gestational age < 32 weeks) recruited from Project on Premature and Small for Gestational Age Infants and full-term-born controls (37 to 42 weeks) recruited from a children's hospital in Rotterdam, The Netherlands. All individuals were 20 years of age at the time of study. Predictors: Gestational age and birth weight: premature and small for gestational age (SGA; n = 23), premature and appropriate for gestational age (n = 29), and controls (n = 30). Outcomes & Measurements: Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and filtration fraction before and after renal stimulation with low-dose dopamine infusion and oral amino-acid intake. Urine albumin and renal ultrasound. Results: Height, weight, kidney length and volume, GFR, and ERPF were significantly lower in the SGA group than in controls. After adjustment for body surface area, GFR did not differ significantly among groups. Mean ERPF was 71 mL/min/1.73 m(2) (95% confidence interval [Cl], 3 to 139) less, but filtration fraction was only 1.3% (95% Cl, -0.3 to 3.0) greater, in the SGA group than controls. Renal stimulation significantly increased GFR and ERPF and decreased filtration fraction in all groups. After renal stimulation, ERPF was 130 mL/min/1.73 m(2) (95% Cl, 21 to 238) greater in the SGA group than controls, but GFR and filtration fraction did not differ significantly among groups. Microalbuminuria was present in 2 patients (8.7%) in the SGA group, but none in the appropriate-for-gestational-age group or controls. Renal function correlated with renal size. Limitations: Small sample size. Conclusions: Our findings do not fully support the hypothesis that preterm birth in combination with intrauterine growth restriction contributes to renal function alterations at young adult age. Larger studies are needed to evaluate this hypothesis.