The kidneys perform several functions:
maintaining the salt and water balance by regulating the plasma concentration of electrolytes (sodium, potassium, chlorine, calcium, magnesium and phosphates) and eliminating excess fluid through the urine
regulating the acid-base equilibrium (blood pH control) through the reabsorption of bicarbonates and the excretion of hydrogen ions
eliminating the terminal products of metabolism (urea, uric acid, creatinine etc.) and foreign substances (pharmaceutical drugs)
producing hormones, including erythropoietin, which stimulates the formation of red blood cells, and renin, which regulates blood pressure
regulating calcium metabolism, which is crucial for our bones, by activating vitamin D.
The kidneys are two bean-shaped organs located in the abdominal cavity, just below the diaphragm, one on each side of the spine.
Most people have two kidneys; however, it is possible to lead a normal life with only one kidney, which can compensate the functioning of the missing one.
When the kidneys are unable to perform their functions, excess fluid and dregs accumulate in the blood. This results in water and salt retention, which can lead to an onset of oedema (excess of fluid in the tissues) and higher blood pressure. The excess fluid can also accumulate in the respiratory system, resulting in acute pulmonary oedema (fluid in the lungs); this condition may, in some cases, lead to death.
Other possible complications from kidney failure include:
electrolyte alterations, in particular hyperkalaemia (high potassium concentration in the blood), which may cause an onset of cardiac arrhythmia
metabolic acidosis, characterised by low blood pH and bicarbonate deficiency
anaemia, due to a lower production of erythropoietin
alterations in calcium and phosphorus metabolism, resulting in increased parathyroid hormone, bone lesions and vascular calcifications.
Kidney failure can be:
acute: the kidney functions are compromised very quickly (it can be reversible)
chronic: the deterioration of kidney function is slow, progressive and irreversible.
The main causes of chronic kidney failure are hypertension and diabetes mellitus.
For this reason, patients with one or both conditions should closely follow the therapy indicated by their physician and have periodical blood and urine tests to assess their renal function.