One of the important functions of our kidneys is the synthesis of hormones, some of which are: erythropoietin, calcitriol (the active form of vitamin D3) and renin.
They also synthesize prostaglandins, which affect a number of processes related to physiological functions in the human body.
In addition to synthesis, kidneys are also involved in the breakdown of certain hormones – such as insulin or parathyroid hormone.
Erythropoietin is a peptide hormone that regulates erythropoiesis, consist of 165 amino acids.
In adults, approximately 90% of erythropoietin is synthesized in the kidneys and the remaining 10% is synthesized by hepatocytes and interstitial Ito cells of the liver (important during fetal and perinatal periods).
Erythropoietin secretion is controlled by the level of oxygen saturation in the blood. Under conditions of hypoxia (insufficient oxygen supply to cells and tissues), plasma erythropoietin increases. Hypoxia might be due to anemia, decreased oxygen capacity, decreased oxygen saturation of hemoglobin molecules, etc.
Vitamin D taken with food or formed in the skin is hydroxylated in the liver and then in the kidneys to 1,25-dihydroxycholecalciferol, which is the biologically active form of vitamin D called calcitriol. Vit. D facilitates and maintains the intestinal absorption of calcium and those of phosphorus. It supports normal bone mineralization and its deficiency leads to osteoporosis in adults and rachitis in children.
Renin is a hormone produced by the kidneys which has leading role in controlling blood pressure and other important physiological functions.
It is an enzyme involved in the renin-angiotensin system (RAS), which regulates blood plasma, lymph and intestinal fluid through arterial vasoconstriction. Performing that function the blood pressure in the human body is regulated.
Prostaglandins are a group of lipids that have a great influence on the basic physiological processes in the body. Prostaglandins are hormones that are not synthesized by the glands, but are created during a chemical reaction at the site of injury or inflammation. Prostaglandins, which are produced by platelets, are actively involved in the blood clotting process and in the blood thinning process.