Proteinuria and Renal Dysfunction Due to Extremely Low Birth Weight in a Patient with Silver-Russell Syndrome.

A 36-year-old woman diagnosed with Silver-Russell syndrome during childhood presented to our department after a primary care physician suspected renal dysfunction. At birth, she had an extremely low weight (1210 g), and in childhood, she was diagnosed with Silver-Russell syndrome. At the age of 14 she was found to have proteinuria; however, the condition was never further examined. One month prior to her presentation to our department, the following were noted: 3+ urinary protein, 3.9 urinary protein/creatinine ratio, and 48 mL/min/1.73 m² estimated glomerular filtration rate. Abdominal computed tomography revealed small kidneys difficult to visualize using ultrasound. Therefore, an open renal biopsy was performed. The renal biopsy revealed no significant findings in the glomerulus except glomerular hypertrophy, and the glomerular density in the cortical area was low (0.6/mm²). The patient was diagnosed with oligomeganephronia. Proteinuria and renal dysfunction were likely due to glomerular hyperfiltration resulting from a low nephron count caused by low birth weight. Silver-Russell syndrome is characterized by intrauterine growth retardation and additional developmental disorders after birth. Here, we detected oligomeganephronia following kidney biopsy in a patient with Silver-Russell syndrome. We suspect that a reduced number of nephrons due to low birth weight caused proteinuria and renal dysfunction.