If a patient with iodine deficiency receives a fixed dose of exogenous T4, which consequence follows regarding T3 production?

💡 Explanation

Peripheral conversion of T4 to T3 relies on deiodinase enzymes, which require selenium as a cofactor. Iodine deficiency often coexists with selenium deficiency, therefore the deiodinase enzymes are less effective and conversion is impaired, rather than being enhanced or fully compensated. Thus, even with T4 supplementation, T3 production remains suppressed.

• If a researcher introduces a TNF-α inhibitor to counteract inflammation at a localized injury site, which consequence is most likely?
• During resistance training, why does eccentric contraction induce greater muscle hypertrophy compared to concentric contraction at the same load?
• If a patient has a genetic defect causing continuously elevated cytosolic phospholipase A2 (cPLA2) activity, which consequence is most likely within inflammatory cells?
• A patient with liver cirrhosis develops impaired synthesis of clotting factors. Which risk increases as a direct result of insufficient thrombin activation in the coagulation cascade?
• In pancreatic beta cells, what distinguishes insulin secretion in response to a gradual rise in blood glucose from that in response to a sudden, equivalent spike?
• Why does progressive macular degeneration impair high-resolution vision while preserving peripheral vision?