"Health Science I Practice Test 2026 – The Comprehensive Guide to Master Anatomy, Physiology & Medical Conditions!"

When iodine is scarce, the thyroid can’t make enough thyroid hormones (T3 and T4). The drop in hormones signals the pituitary to release more TSH to stimulate the thyroid. Over time, this constant stimulation makes the gland enlarge in an attempt to trap more iodine and boost hormone production, producing a goiter. Other conditions listed—anemia, diabetes, and asthma—result from issues with iron metabolism, insulin/glucose control, or airway inflammation, not from iodine lack.