Glucosuria is a pathological condition characterized by the detection of glucose in a urine sample. The causes may be diseases of the pancreas, various endocrine disorders, kidney disease. Glucosuria itself has no clinical manifestations. Prolonged excretion of large amounts of glucose in the urine increases the risk of developing urinary tract infections (pyelonephritis, cystitis). The glucose level is examined on an empty stomach in a medium portion of freshly collected urine. Correction of this laboratory deviation is carried out by treating the underlying disease.
Normally, urine does not contain glucose, since it is almost completely reabsorbed from the renal tubules. Those small amounts of glucose present in the urine of a healthy person are not detected by standard diagnostic methods. However, there are physiological situations in which glucosuria can occur.
For example, in young children (due to a low renal threshold for glucose), during pregnancy (due to an increase in the glomerular filtration rate), after taking a large amount of carbohydrate food (alimentary glucosuria). In clinical practice, pathological glucosuria is usually divided into 2 large groups:
Incorrect results can be obtained when determining glucose levels in a urine sample:
The most common cause of glucosuria is diabetes mellitus. With a relative or absolute deficiency of insulin, the consumption of glucose by tissues and the formation of glycogen from it in the liver are greatly slowed down, which leads to hyperglycemia, and, accordingly, an increase in its content in the urine. Glucosuria values can range from traces up to 12 g/10 ml.
The degree of glucosuria does not correspond in any way with its concentration in the blood, however, it directly correlates with the severity of polyuria. It should be borne in mind that in patients with diabetes over the years, glucose reabsorption in the kidneys increases significantly, therefore, even with a high level of glycemia, glucosuria may be completely absent. In some elderly patients, the renal threshold reaches 16 mmol / l.
Even after the appointment of competent treatment and the achievement of a stable normalization of blood glucose and compensation for diabetes, glucosuria can persist, so the concentration of glucose in the urine is only an indicative indicator that requires further examination. Only on the results of a urinalysis it is impossible to make or exclude the diagnosis of diabetes mellitus, as well as to judge the adequacy of therapy.
In acute pancreatitis, glucosuria is a temporary phenomenon and disappears when the inflammatory process subsides. In severe pancreatitis or pancreatic necrosis, the islets of Langerhans, which produce insulin, die, which can lead to the development of diabetes mellitus.
Some diseases of the endocrine system are accompanied by hypersecretion of hormones - thyroxine, glucocorticoids, catecholamines, tropic hormones (thyroid-stimulating, adrenocorticotropic, somatotropic). These hormones have a contra-insular effect, i.e. they cause an increase in blood and urine glucose levels. Glucosuria occurs in approximately 25-30% of those with endocrine disorders. Glucose levels normalize fairly quickly after specific treatment.
The causes of hormonal glucosuria are as follows:
Violation of glucose reabsorption in the proximal tubules of the nephron leads to an increase in its concentration in the urine. This can be observed with isolated renal glucosuria, a benign disease that does not require any treatment. But more often it occurs in tubular dysfunctions - renal tubular acidosis, Fanconi syndrome. With organic pathologies of the kidneys (glomerulonephritis, acute kidney injury), glucosuria is observed much less frequently and is of a moderate nature.
Glycosuria is considered a characteristic manifestation of some diseases accompanied by tubular dysfunction (Wilson-Konovalov disease, cystinosis, vitamin D-resistant rickets). In addition to the excretion of glucose in the urine, an increased excretion of amino acids, bicarbonates, and phosphates is found.
A distinctive feature of renal glucosuria is that the plasma glucose level remains normal, and sometimes low, even despite severe glucosuria. The degree of glucosuria depends on the severity of the nephrological disease. Many patients may have high levels of glucose in their urine after treatment.
Damage to the central nervous system of various origins (traumatic, mechanical, toxic) in some cases leads to glucosuria. The pathogenetic mechanism is explained by the fact that with a serious lesion of the central nervous system, activation of the sympathetic-adrenal, hypothalamic-pituitary-adrenal systems occurs, followed by the release of contra-insular (stress) hormones into the blood.
Under the influence of these hormones, the breakdown of glycogen in the liver increases, hyperglycemia develops, then glucosuria. Central glucosuria, as a rule, is short-lived, temporary, and regresses on its own. The causes of this laboratory disorder are as follows:
If glucosuria is detected, it is necessary to consult a general practitioner to find out the cause of its occurrence. Anamnestic data are important - the doctor clarifies whether the patient was diagnosed with diabetes mellitus, whether the intake of carbohydrate food preceded the test, what medications he takes.
Information about whether the patient is registered with other specialists (nephrologist, endocrinologist) may be useful. The glucose level is most often examined in a general urinalysis using polyfunctional test strips that allow you to determine several indicators. Monofunctional glucose-only urinary strips also exist. To more accurately determine the loss of glucose in the urine, the doctor may prescribe a glucose test in daily urine.
Special attention is paid to vitamin C - if a positive urine glucose result is combined with a high concentration of ascorbic acid, the analysis should be repeated, and not earlier than 24 hours after the last intake of vitamin C. Attention is drawn to other indicators (protein, red blood cells, white blood cells ), the identification of which can help in the differential diagnosis of the etiological factor. An additional examination is scheduled, including:
Urine glucose test
There is no need to correct glucosuria itself, it is necessary to treat the disease against which it developed. If a drug is the cause of the glucosuria, either reduce its dosage or consider discontinuing it. Depending on the etiology, the patient is prescribed:
With the ineffectiveness of conservative therapy for type 2 diabetes, bariatric surgery is performed - gastric banding, gastric bypass or resection. For the treatment of endocrinopathies, the following operations are required - thyroidectomy for thyrotoxicosis, adenomectomy for acromegaly, adrenalectomy for Cushing's syndrome. In case of pancreatic necrosis, the abdominal cavity is opened with excision of necrotic tissue, sanitation and drainage.
Since glucose is a breeding ground for bacteria, long-term glucosuria increases the risk of urinary tract infections several times. The most serious consequences for human health and life depend on the underlying pathology. The most unfavorable prognosis with high mortality is observed in pancreatic necrosis, brain tumors.
In diabetes mellitus, the prognosis can be difficult, but with proper therapy and constant glycemic control, complications are extremely rare. Detection of glucosuria in pregnant women requires further examination to rule out gestational diabetes. The most benign course without any threat to life is typical for people with isolated renal glucosuria.