In renal physiology, renal sodium reabsorption refers to the process by which the kidneys, having filtered out waste products from the blood to be excreted as urine, re-absorb sodium ions (Na2+) from the waste. It uses Na-H antiport, Na-glucose symport, sodium ion channels (minor).[1] It is stimulated by angiotensin II and aldosterone, and inhibited by atrial natriuretic peptide.
It is very efficient, since more than 25,000 mmol/day of sodium is filtered into the nephron, but only ~100 mmol/day, or less than 0.4% remains in the final urine.