TSH decreased

Etiology

• Primary hyperthyroidism, eg, Graves’ disease, toxic multinodular goiter, toxic nodule, subacute thyroiditis, early Hashimoto’s disease
• Thyroid hormone administration
• Severe nonthyroidal illness
• Dopamine or dopamine agonists (levodopa, bromocriptine)
• Pregnancy
• hCG-secreting trophoblastic tumor
• Acute psychiatric illness
• Acute glucocorticoid administration
• Other drugs, eg, NSAIDs, amphetamines, octreotide, opioids, nifedipine, verapamil
• "Subclinical" hyperthyroidism: low TSH, clinically euthyroid, normal T4, common in elderly (10%), risk of atrial fibrillation and osteoporosis