Which of the following is not a function of our kidneys?

Ammonia produced by metabolism is converted into urea in the liver (through ornithine cycle)  and released into the blood which is filtered and excreted out by the kidneys.Kidneys regulate blood pH by excreting hydrogen ions and conserving bicarbonate ions.Kidneys regulate blood pressure by secreting renin. Renin-angiotensin-aldosterone pathway leads to an increase in blood pressure. Kidneys also regulate blood pressure by regulating the reabsorption of water.Calcitriol, the active form of vitamin D, is produced in the kidneys.