Which hormone increases in response to decreased urinary output and dehydration?

Which hormone increases in response to decreased urinary output and dehydration?

• A. Creatinine
• B. Uric Acid
• C. Aldosterone
• D. Lactate Dehydrogenase (LDH)

Answer: (C)

Dehydration and decreased urine output trigger the renin-angiotensin-aldosterone system. When kidney perfusion drops, renin release leads to angiotensin II formation, which stimulates the adrenal cortex to secrete aldosterone. Aldosterone acts on the distal tubules and collecting ducts to increase sodium reabsorption; water follows sodium, expanding blood volume and reducing urine output. Among the options, aldosterone is the hormone that directly promotes salt and water reabsorption to conserve volume in this situation. Creatinine, uric acid, and LDH are not regulatory hormones for fluid balance; they are waste products or enzymes that don’t drive the reduced urine output seen with dehydration. (Note: ADH also rises with dehydration to conserve water, but it isn’t listed here.)

Dehydration and decreased urine output trigger the renin-angiotensin-aldosterone system. When kidney perfusion drops, renin release leads to angiotensin II formation, which stimulates the adrenal cortex to secrete aldosterone. Aldosterone acts on the distal tubules and collecting ducts to increase sodium reabsorption; water follows sodium, expanding blood volume and reducing urine output. Among the options, aldosterone is the hormone that directly promotes salt and water reabsorption to conserve volume in this situation. Creatinine, uric acid, and LDH are not regulatory hormones for fluid balance; they are waste products or enzymes that don’t drive the reduced urine output seen with dehydration. (Note: ADH also rises with dehydration to conserve water, but it isn’t listed here.)