Urine may have been produced in abnormal amounts or have abnormal appearance or composition.
Some conditions can cause excess urine to be passed: in adults, more than about 3 litres of urine per day. In contrast, abnormally low urine production, of less than about 0.4 litres per day, can occur in extreme dehydration or acute kidney failure. If extremely damaged, the kidneys can fail to produce any urine. Obstruction of the urinary tract by a stone, for example, can also cause cessation of urine flow.
Cloudy urine can be due to a urinary tract infection, the presence of salts, or a stone. Haematuria (blood in the urine) can be due to bleeding in the urinary tract. Urine can become discoloured due to ingestion of some drugs or foods. An excess of protein can cause urine to turn frothy.
Some disorders cause abnormal substances to be excreted in the urine. In diabetes mellitus, glucose enters the urine. Glomerulonephritis (inflammation of the filtering units of the kidneys) or nephrotic syndrome cause protein to leak into the urine. Certain disorders cause abnormal levels of normal waste products or other chemical imbalances. Kidney failure reduces the total amounts of waste products, or other chemical imbalances. Kidney failure reduces the total amounts of waste products such as urea. Other kidney disorders, such as Fanconi’s syndrome and renal tubular acidosis, can make the urine too alkaline or acid, or can cause it to contain excess amino acids, salts , phosphates, or water.