Laboratory Evaluation of Patients for Thyroid Disease Hyperthyroidism: • Graves disease - TSH low; free T4 high; in some cases, T3 is elevated and free T4 is normal; TRAbs or TSI elevated • Toxic multinodular goiter - TSH low; free T4 and T3 normal or high; normal or increased radioactive iodine uptake; thyroid scan with multiple areas of increased uptake surrounded by suppressed uptake • Toxic adenoma - TSH low; free T4 and T3 normal or high; normal or increased radioactive iodine uptake; thyroid scan with focal increased uptake in tumor surrounded by suppressed uptake in nontumor tissue • Subacute thyroiditis - TSH low; free T4 and T3 high; increased; decreased radioactive iodine uptake • Painless thyroiditis - TSH low; free T4 and T3 high; erythrocyte sedimentation rate normal; decreased radioactive iodine uptake Hypothyroidism: • Hashimoto thyroiditis - TSH high; T4 normal and then low, preceding a decline in T3; anti-TPO and/or antithyroglobulin antibody positive • Ablative hypothyroidism - TSH high; free T4 and T3 low following procedure that ablates thyroid • Infantile hypothyroidism - TSH high; free T4 low in a newborn or infant • Euthyroid sick syndrome - TSH normal to high; free T4 normal; T3 low; rT3 high; concentrations of TSH and thyroid hormones vary throughout disease course #hypothyroid #hyperthyroid #differential #diagnosis #endocrinology
