Proteinuria caused by glomerular hypertension during adolescence associated with extremely premature birth: a report of two cases

Background: Prematurity and low birth weight are risk factors for the future development of chronic kidney disease (CKD) and hypertension caused by fewer nephrons with limited filtration surface area. Few reports to date have evaluated their clinical backgrounds and pathological findings, including glomerular hypertension and focal segmental glomerulosclerosis. Case-Diagnosis/Treatment: This report describes two patients, a 15-year-old girl (patient 1), with a birth weight of 618 g and a gestational age of 24 weeks, and a 14-year-old boy (patient 2), with a birth weight of 842 g and a gestational age at 25 weeks. Both had a birth weight appropriate for gestational age. Both were first diagnosed with proteinuria during adolescence, and patient 2 also had hypertension. Pathological findings included glomerulomegaly in both and hypertrophy of the juxtaglomerular apparatus and perihilar glomerulosclerosis in patient 1, suggesting glomerular hypertension. Treatment with lisinopril resulted in the immediate disappearance of proteinuria. Renal dysfunction was observed in both patients, but neither showed evidence of severe aggravation after a follow-up of 5 or 6 years. Conclusions: Proteinuria in both patients was caused by glomerular hypertension with hyperfiltration. Extremely preterm birth itself may be a risk factor for future CKD. Long-term follow-up of patients born prematurely and at low birth weight, including urinalysis and blood pressure measurements, is necessary to diagnose and treat late renal complications.