Reduced TSH
July 29th, 2019
Overview
A suppressed TSH is suggestive of primary hyperthyroidism.
Causes of Reduced TSH
Primary Hyperthyroidism
- Grave's disease
- Toxic multinodule goitre
- Toxic nodule
- Thyroiditis - postviral, postpartum, lymphocytic
- Drugs - thyroxine, amiodarone, iodine
- Pregnancy-related - hyperemesis gravidarum, hydatidiform mole
- Struma ovarii
- Congenital hyperthyroidism
Other
- Subclinical hyperthyroidism
- Nonthyroidal illness
- Central hypothyroidism
- Congenital TSH or TRH deficiency
Interpretation
- Supressed TSH with elevated T4 - suggestive of primary hyperthyroidism
- Suppressed TSH with normal T4 - suggestive of subclinical hyperthyroidism
- Suppressed TSH with reduced T4 - suggestive of nonthyroidal illness or central hyperthyroidism
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