22nd June 2023

Hormone production

The kidneys are the main source of erythropoietin (EPO) production, a hormone which stimulates the production of red blood cells. In cases of severe kidney disease, anaemia can result from reduced EPO production.

Renin is an enzyme stored in the juxtaglomerular cells of the kidney in its inactive form and is activated and released in response to low arterial blood pressure. This triggers the renin-angiotensin-aldosterone system, a cascade of vasoactive substances and hormones which work to ultimately increase arterial blood pressure.

The kidney also has a role in the hydroxylation of inactive vitamin D to its active form, 1,25-dihydroxyvitamin D3, also known as calcitriol. Calcitriol has an important role in calcium homeostasis by increasing the deposition of calcium into the bones and increasing the reabsorption of calcium in the gastrointestinal tract.