Calciuria, oxaluria and phosphaturia after ingestion of glucose, xylitol and sorbitol in two population groups with different stone-risk profiles

The effects of glucose, sorbitol and xylitol ingestion on calciuria, oxaluria and phosphaturia in healthy black and white males on a standardized diet were investigated. After ingestion, they collected urine hourly for 3 h. Glucose decreased phosphaturia in blacks. Sorbitol decreased phosphaturia in both groups and increased oxaluria in whites. Xylitol increased oxaluria in blacks. Decreases in phosphaturia are attributed to penetration by phosphate into cells leading to decreases in phosphatemia and the renal filtered load. We suggest that this mechanism is more sensitive in blacks. We speculate that the increase in oxaluria after sorbitol ingestion occurs via its conversion to glyoxylate and that this pathway may be blocked in blacks. For the increase in oxaluria after xylitol ingestion, it is hypothesized that ketohexokinase and aldolase may be more active in blacks. Our results demonstrate, for the first time, a urinary effect due to sorbitol ingestion and an ethnic dependency of these and other effects.