Social & Preventive Medicine The most sensitive indicator of ‘Environmental iodine deficiency’ is:- A Serum T4 levels B Serum T3 levels C Urine iodine excretion D Neonatal hypothyroidism 💡 Explanation The most sensitive indicator of 'Environmental iodine deficiency' is:- ✓ Correct Answer: D. Neonatal hypothyroidism