Thyroid Disorders

The thyroid sets the pace of the body's metabolism, and disorder of it runs in two directions. Too little hormone slows everything: weight creeps up, the bowels slow, the skin dries and cold becomes hard to tolerate. Too much speeds everything: the pulse races, weight falls despite a good appetite and the hands tremble.

Most of it is autoimmune. An antibody either destroys the gland gradually or switches it permanently on, and which of the two you have is a blood test and not a guess from symptoms.

The first test is TSH, the signal the pituitary sends to the thyroid. It rises when the gland is underperforming and is suppressed when the gland is overactive, so it points the direction before anything else is measured.

Thyroxine confirms it, and thyroid antibodies say whether the cause is autoimmune. Where the gland is overactive your doctor also separates Graves' disease from a single hot nodule and from a gland that is simply inflamed and leaking stored hormone, because the three are treated differently. The neck is examined for a goitre or a nodule, and the pulse is checked for an irregular rhythm.

An underactive thyroid is corrected with a daily tablet taken on an empty stomach, and the level is rechecked six to eight weeks after any change, because that is how long TSH takes to respond. Symptoms often lag the blood result by a few weeks.

An overactive gland settles over four to eight weeks on tablets, with a course usually running twelve to eighteen months. Any sore throat with fever while on antithyroid tablets needs a blood count the same day, since a rare effect is a sudden drop in white cells.