Hyperthyroidism Testing: Confirming an Overactive Thyroid

The confirmation pattern

Low TSH + elevated Free T4 (±T3) = biochemical hyperthyroidism. Then etiology sorting begins: TRAb-positive suggests Graves' (autoimmune whole-gland stimulation); TRAb-negative with asymmetric uptake suggests toxic nodules; transient patterns follow postpartum or viral thyroiditis (often resolving without ablative therapy).

Symptoms that trigger testing

Palpitations/racing heart, tremor, anxiety/irritability, heat intolerance/sweating, weight LOSS despite normal-or-increased appetite, loose stools, insomnia, thinning skin/hair, cycle lightening, and in older adults — unexplained atrial fibrillation or apathetic presentation masquerading as depression.

Special situations

• Pregnancy: hCG physiologically suppresses TSH early — trimester-specific ranges prevent misdiagnosis; true Graves' complicates fetal management (TRAb crosses placenta)
• Elderly: 'apathetic hyperthyroidism' presents as lethargy/weight loss/depression rather than classic hyperactivity
• T3-toxicosis: T3 elevates alone with normal T4 — total picture requires T3 measurement

Treatment pathways depend on testing

Antithyroid medications (methimazole), radioactive iodine ablation, or surgical removal — selection integrates TRAb status, uptake-scan patterns, goiter geometry, pregnancy plans, and comorbidities. Post-ablation hypothyroidism is the EXPECTED endpoint requiring replacement thereafter.