Renal

Renal is an adjective used in medicine to denote relations to the kidneys, which are a pair of retroperitoneal organs responsible for filtering blood and producing urine. Each kidney contains about a million nephrons and receives blood through a renal artery, returning blood via a renal vein.

The kidneys have a cortex and a medulla. The nephron is the functional unit and includes the glomerulus, proximal tubule, loop of Henle, distal tubule, and collecting duct. Filtrate is produced in the glomerulus and modified along the tubules. Blood is supplied by the afferent arteriole, and drained by the efferent arteriole into the peritubular capillaries, which facilitate reabsorption and secretion.

The kidneys regulate fluid and electrolyte balance, acid-base homeostasis, and blood pressure; they excrete waste and help conserve water. They form concentrated urine under antidiuretic signals. Endocrine roles include secretion of renin, erythropoietin, and activation of vitamin D.

Renal function is evaluated using serum creatinine, estimated glomerular filtration rate (eGFR), urinalysis, and measurement of albuminuria. Imaging studies may assess anatomy and obstruction. Common conditions affecting renal function include chronic kidney disease, acute kidney injury, nephrolithiasis (kidney stones), and infections such as pyelonephritis.

Treatments aim to prevent progression and manage symptoms. They include medical control of diabetes and hypertension, dietary modifications, and in advanced disease, renal replacement therapy such as dialysis or kidney transplantation. Prevention focuses on controlling risk factors and avoiding nephrotoxins.