Renal Glucosuria.

Renal Glucosuria

Etiology, pathogenesis. Renal glycosuria develops as a result of a hereditary defect in the enzyme systems of the renal tubules that ensure the reabsorption of glucose. Renal glucosuria should be considered in cases where the excretion of glucose in the urine exceeds the level of physiological excretion (200 mg/day).

With renal glucosuria, the daily excretion of glucose in the urine is usually 10-20 g, although cases of glucosuria reaching 100 g are known. The frequency of renal glucosuria is 2-3: 1000; the type of inheritance is autosomal dominant.

Clinical picture.

Clinical symptoms (except glycosuria) are observed mainly in very severe cases and are caused by significant losses of sugar. Patients experience weakness and hunger. Persistent osmotic diuresis (polyuria) causes the development of dehydration and hypokalemia.

Carbohydrate deficiency may be associated with delayed physical development of the child.

Diagnosis. The criteria for renal glucosuria are: 1) increased excretion of glucose with normal blood sugar levels; 2) independence of glucose excretion in urine from the intake of carbohydrates; glucose excretion is relatively constant both during the day and at night; 3) no changes in blood sugar levels when carbohydrates are consumed; 4) identification of sugar excreted in urine as glucose; 5) normal sugar curve after a glucose load.

In addition to diabetes mellitus, when differentially diagnosing renal glucosuria, it is necessary to keep in mind melituria of a different nature, in particular melituria in acute tubular necrosis, toxic kidney damage, “steroid diabetes” when using glucocorticoids for therapeutic purposes, fructosuria, pentosuria. Positive tests for sugar in the urine can be detected with benign fructosuria. The absence of other clinical signs in these cases may lead to the conclusion about the possibility of renal glycosuria.

Identification of carbohydrates excreted in urine is necessary.

You should also keep in mind complex syndromes in which renal glucosuria manifests itself as a particular symptom: gluco-aminophosphate-diabetes, gluco-amino-diabetes, gluco-phosphate-diabetes. This circumstance requires a mandatory study of the amount of excretion of phosphates and amino acids in each patient with renal glucosuria.

Treatment. There are no methods of pathogenetic therapy for this disease. It is important to provide the patient with proper nutrition to avoid carbohydrate overload and hyperglycemia, which contributes to increased sugar losses.

With the development of hypoglycemia, it may be necessary to additionally administer glucose, and in case of hypokalemia, it is advisable to introduce foods containing large amounts of potassium (raisins, carrots, etc.).

The prognosis is favorable.

Prevention: medical and genetic counseling.