Background: Low birthweight infants have a reduced number of nephrons and are at high risk of chronic kidney disease. Preterm birth and/or intrauterine growth restriction (IUGR) may also affect peritubular capillary development, as has been shown in other organs.
Case-diagnosis/treatment: We report two patients with a history of preterm birth and extremely low birthweight who showed polycythemia and renal capillary rarefaction.