Subclinical thyrotoxicosis.

Subclinical thyrotoxicosis as a definite entity has been recognised with the development of highly sensitive immunometric TSH assays. The condition is characterised by suppressed TSH in presence of normal T3 and T4. It may be due to exogenous or endogenous causes. The risks may be osteoporosis and atrial fibrillation. Exogenous subclinical thyrotoxicosis must be prevented by optimising laevothyroxine dosage. Endogenous subclinical thyrotoxicosis may or may not be treated depending upon the clinical situation and existing comorbidities.