What are the other functions of kidney other than excretion?

In addition to excretion, the kidneys play crucial roles in regulating blood pressure through the renin-angiotensin-aldosterone system, maintaining electrolyte balance, and controlling acid-base homeostasis by excreting hydrogen ions and reabsorbing bicarbonate. They also produce hormones such as erythropoietin, which stimulates red blood cell production in the bone marrow, and convert vitamin D into its active form, calcitriol, aiding in calcium absorption and bone health.