(See also Introduction to Disorders of Kidney Tubules.)
In renal glucosuria, glucose (sugar) is excreted in the urine, despite normal or low glucose levels in the blood.
Normally, the body excretes glucose in the urine only when glucose levels in the blood are very high (such as in uncontrolled diabetes mellitus). In most healthy people, glucose that is filtered from the blood by the kidneys is completely reabsorbed back into the blood. In people with renal glucosuria, glucose may be excreted in the urine despite normal or low levels of glucose in the blood. This happens because of a defect in the tubular cells of the kidneys that decreases the reabsorption of glucose.
Some forms of renal glucosuria are hereditary, causing glucosuria alone or as part of Fanconi syndrome. The acquired form can be caused by certain drugs or diseases that damage the kidney tubules.
Renal glucosuria has no symptoms or serious consequences.
A doctor makes the diagnosis when a routine urine test detects glucose in the urine even though glucose levels in the blood are normal.
No treatment is needed.