ABSTRACT
Humans have two kidneys, both weighing about 160 g and measuring 10–15 cm long. They filter the toxins and waste products from the blood, and these are then excreted in the urine. Each kidney contains approximately 2 million microscopic sieves called nephrons, which consist of networks of capillaries called glomeruli, where the first phase of filtration occurs. The kidneys secrete some essential hormones such as erythropoietin, which is needed to make red blood cells. Normal urine is straw coloured and transparent. The colour of the urine can also be altered by medication, foodstuff and disease. Bright yellow urine can be caused by some vitamins and other medications. A faecal smell could mean that there is a fistula, or direct connection between the bowel and bladder where faeces is able to contaminate the urine. The presence of various substances in the urine that can be detected on the dip test can be very useful to the clinician in making a diagnosis.
