How is hypothyroidism diagnosed in relation to blood test values?
The diagnosis of hypothyroidism is not easy because the onset of the condition may take many years. Subtle changes in biochemistry blood test results usually precede symptoms. The most sensitive indicator of developing hypothyroidism is a rise in the TSH result. Generally a TSH result of <5 is regarded as biochemically ‘normal’, a result of 5-10 is borderline and a result of >10 (in a patient who is not acutely ill) is regarded as consistent with hypothyroidism. The biochemical results have to be considered along side clinical symptoms, and together they determine the point at which the physician will introduce Thyroxine therapy.
