Blood is filtered by millions of nephrons, the functional units that comprise the kidneys. In each nephron, blood flows from the arteriole into the glomerulus, a tuft of leaky capillaries. The Bowman's capsule surrounds each glomerulus, and collects the filtrate that the glomerulus forms. The filtrate contains waste products (e.g. urea), electrolytes (e.g. sodium, potassium, chloride), amino acids, and glucose. The filtrate passes into the renal tubules of the kidney. In the first part of the renal tubule, the proximal tubule, glucose is reabsorbed from the filtrate, across the tubular epithelium and into the bloodstream. The proximal tubule can only reabsorb a limited amount of glucose (~375 mg/min), known as the transport maximum. When the blood glucose level exceeds about 160–180 mg/dL (8.9-10 mmol/L), the proximal tubule becomes overwhelmed and begins to excrete glucose in the urine. +Approximate correlation between dipstick designation and urine concentration of glucose Urine dipstick designation Approximate urine concentration trace 100 mg/dL 1+ 250 mg/dL df 2+ 500 mg/dL 3+ 1000 mg/dL 4+ 2000 mg/dL This point is called the renal threshold for glucose (RTG). Some people, especially children and pregnant women, may have a low RTG (less than ~7 mmol/L glucose in blood to have<unk> . If the RTG is so low that even normal blood glucose levels produce the condition, it is referred to as renal<unk> . Glucose in urine can be identified by Benedict's qualitative test. If yeast is present in the bladder, the sugar in the urine may begin to ferment, producing a rare condition known as urinary auto-brewery syndrome.
Glycosuria
Xanthinuria
Hawkinsinuria
Orotic aciduria
Pentosuria
Galactosemia
Aminoaciduria
Alkaptonuria