The relation between age and renal concentrating capacity in sickle cell disease and hemoglobin C disease

1. 1. Renal Concentrating Capacity (RCC) and Glomerular Filtration Rate (GFR) were investigated in groups of subjects of different ages suffering from sickle cell anemia (SS(+F)), sickle cell trait (AS), sickle cell hemoglobin C disease (SC), hemoglobin C disease (CC) and hemoglobin C trait (AC). The RCC of SS(+F) patients aged 10 years and older falls into a very narrow range (mean 434 mOsm: S.D. ± 21), in those younger than 10 years the RCC is much more variable ranging from 460–687 mOsm. As subjects, on the other hand, show a significant progressive decrease in RCC with age. The youngest patients have an almost normal concentrating capacity and the oldest subjects are unable to concentrate better than to the fixed maximum of the anemia group. SC patients also demonstrate a declining RCC, but on a lower level than in the AS subjects, for all age groups; the RCC of the elder ones show the same fixed maximum as in SS(+F). CC and AC subjects have a normal RCC. In none of the groups investigated was a correlation found between RCC and GFR. 2. 2. In three AS patients urine was collected simultaneously from the right and left kidney during hydropenia or vasopressin infusion. The results indicate that the concentrating defect affects both kidneys in the same degree.