Renal glucosuria is the excretion of glucose in the urine in detectable amounts at normal blood glucose concentrations in the absence of any signs of generalized proximal renal tubular dysfunction. The inherited from of this disorder is called familial renal glucosuria (FRG). In general, renal glucosuria is a benign condition and does not require any specific therapy. Glucosuria may be associated with tubular disorders such as Fanconi-de Toni-Debre syndrome, cystinosis, Wilson disease, hereditary tyrosinemia, or oculocerebrorenal osteodystrophy (Lowe syndrome). Renal glucosuria has also been reported in patients with acute pyelonephritis in the presence of a normal blood glucose level. Glucose loss in the urine may vary from a few grams to more than 100g (556 mmol) per day.
Under normal circumstances, the kidney reabsorbs approximately 180 g of glucose from the glomerular filtrate each day. The glucose transporters in the renal proximal tubule ensure that less than 0.5 g/day (range 0.03-0.3 g/d) is excreted in the urine of healthy adults. Whereas mild renal glucosuria is relatively frequent, heavy glucosuria is extremely rare.
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