ABSTRACT
The diagnosis of hypothyroidism relies on laboratory testing because the symptoms are non-specific and multi-systemic. Generally, a rise in thyroid-stimulating hormone with a low level of T4, low level of T3 gives the earliest guide to the onset of hypothyroidism. Prevalence of newly diagnosed overt hypothyroidism is 3-4 per 1000 and the probability of developing hypothyroidism increases with advancing age, reaching 14 per 1000 in women aged between 75 and 80. Hypothyroidism has a tendency to occur in clusters in families, especially in female relatives. Hypothyroidism is a relatively common condition and can be easily managed in the primary care sector. General practitioners know their patients well and can carry out regular monitoring of patients who are at high risk of hypothyroidism, for example, those who have had previous thyroid surgery and radioactive iodine treatment. In hypothyroidism secondary to deficiency of thyroid-stimulating hormone, measurement of free T4 is necessary to guide replacement.
