Clinical diagnosis of the diabetes require some of the laboratory tests, glycosuria (finding glucose in the urine) is one of the significant test for detecting frank diabetes. Those who are non diabetic, for them glycosuria can occur for the short term due to emotional stress, pain, hyperthyroidism, alimentary hyperglycemia or meningitis. It can also occur when there is insufficiency of insulin and if a substantial amount of food with high sugar is consumed.
Glycosuria is a condition in which glucose or simple sugar is detected in the urine despite of normal blood sugar level. The normally functioning kidneys absorb and reabsorb the extra blood sugar till renal threshold, with the help of millions of micro tubules – Nephron (filtering unit of kidney). The renal threshold is a concentration level above which all simple sugar is not absorbed in the blood; hence extra glucose is excreted by the kidneys in the urine. Renal threshold of normal kidney is around 10mmol/L. In few cases, when drugs are used for a longer span of time, it may alter the threshold level of kidney. The amount of glucose not reabsorbed by the kidneys is usually less than 0.1%. Adults excrete about 65 mg of glucose per day. The relationship between glycosuria and the renal threshold are explained in the diagram given below.
In renal glycosuria glucose is abnormally eliminated in the urine due to improper action of the nephron.
The renal glycosuria occurs only when there are abnormally functioning kidneys, due some dent in the kidneys or as an autosomal recessive trait.