Subclinical hyperthyroidism

Abstract

Subclinical hyperthyroidism (SH) is a relatively common disorder; it is defined as a condition in which the thyroid hormones thyroxine (T4) and triiodothyronine levels (T3) are normal with low or even undetectable thyroid-stimulating hormone (TSH) levels. SH may be caused by exogenous or endogenous factors with TSH suppressive therapy in differentiated thyroid cancer or unintentional over-replacement L-T4 therapy being the most common causes. Frank symptoms of hyperthyroidism is most often absent. Patients often present with goitre or for other symptoms of mild thyroid hormone excess such as headache, reduced feeling of well-being, and inability to concentrate. SH leads to increased risk of cardiovascular morbidity and mortality, it may accelerate the development of osteoporosis, and increase bone vulnerability to trauma, especially in postmenopausal women and elderly. It reduces the quality of life, affecting both the psycho and somatic components of wellbeing. Diagnosis of SH is confirmed by repeated testing of TSH spaced months apart in the presence of normal free T3 and T4 concentrations. Radionuclide uptake scan aids us in the diagnosis of the cause of SH. The treatment of SH is similar to the treatment of overt hyperthyroidism, it should be based on the underlying etiology.

Keywords

• american thyroid association guidelines
• bone and mineral metabolism
• cardiovascular effects
• subclinical hyperthyroidism