glukosuria

Glucosuria, or glycosuria, is the excretion of glucose in the urine. In healthy individuals, the kidneys reabsorb most filtered glucose in the proximal tubules, so urine normally contains little or no glucose. Glucosuria occurs when the amount of glucose filtered by the kidneys exceeds the reabsorptive capacity or when reabsorption is impaired.

Common causes and types

The most frequent cause is hyperglycemia due to diabetes mellitus, in which elevated plasma glucose saturates the renal reabsorption mechanism and glucose spills into the urine. Less commonly, glucosuria results from inherited defects in renal glucose transporters (proximal tubule disorders such as renal glucosuria, often due to SGLT2 mutations), or from physiological states that lower the renal threshold for glucose (for example, pregnancy). Medications that promote glucose excretion in urine, such as SGLT2 inhibitors used to treat type 2 diabetes, can also cause glucosuria.

Clinical presentation and diagnosis

Glucosuria may be detected incidentally on a urine dipstick test or may accompany symptoms of hyperglycemia (increased thirst, urination, weight loss). A positive urine glucose test does not distinguish between causes, so evaluation usually includes measurement of blood glucose and HbA1c, plasma-urine glucose correlation, and assessment of kidney function. In suspected proximal tubule disorders, additional tests assess urinary losses of other substances (e.g., amino acids, phosphate) and may include genetic testing.

Management and prognosis

Management depends on the underlying cause. If glucosuria reflects diabetes, treatment focuses on glycemic control and monitoring for diabetes-related complications. Benign familial renal glucosuria due to tubular defects often requires no specific treatment but may warrant periodic monitoring. Glucosuria due to pregnancy or medications may resolve with the underlying condition or discontinuation of the drug.