Loss of kidney function, which may be sudden (acute) or gradual (chronic), as in chronic kidney disease. Loss of kidney function leads to a reduced filtration capacity (The glomerular filtration rate (GFR) is defined as the volume of fluid that is filtered by the glomeruli of the nephrons of both kidneys per unit of time to produce primary urine. It is, therefore, the chief measure of kidney function. The rate corresponds to...) and, thus, an inability to sufficiently filter out urinary substances such as Toxic, nitrogen-containing urinary substances responsible for uraemia and kidney damage..... Renal failure can lead to raised blood Urea is the nitrogen-containing breakdown product of protein metabolism. The nitrogen from the proteins is converted to ammonia in the liver, which is combined with carbon dioxide to form urea. This is continuously excreted via the kidneys but also via sweat. Urea is one of... (A raised level in the blood of urea and other urinary substances, which in chronic kidney disease can no longer be adequately excreted due to impaired renal function (glomerular filtration rate). This leads to renal damage due to uraemic toxins, toxic urinary substances The symptoms...) and its associated symptoms.