During cold exposure, what hormonal changes contribute to diuresis?

During cold exposure, what hormonal changes contribute to diuresis?

• A. Increased AVP/ADH and decreased natriuretic peptide signaling
• B. Reduced AVP/ADH and increased natriuretic peptide signaling
• C. Increased aldosterone and antidiuretic hormone
• D. Decreased atrial natriuretic peptide and decreased renin

Answer: (B)

Cold-induced diuresis happens when the body shifts toward more excretion of water and sodium. The key driver is a fall in AVP/ADH, which reduces water reabsorption in the collecting ducts, combined with a rise in natriuretic peptide signaling (especially atrial natriuretic peptide, ANP) from the stretched heart due to increased central blood volume from cutaneous vasoconstriction. ANP promotes natriuresis and diuresis by increasing GFR and by inhibiting renin-angiotensin-aldosterone activity, which reduces sodium and water reabsorption downstream. This combination—less ADH-driven water retention and more ANP-driven sodium and water loss—best explains the diuresis seen with cold exposure.