[Diagnosis and therapy of hypothyroidism in adulthood]

In the majority of cases, the symptoms of hypothyroidism develop slowly and as a result, they often are not recognized or misjudged for a long time. The complete picture is a late diagnosis. Especially in older patients, the symptoms are quite frequently assigned to the aging process. The most important form is the primary hypothyroidism often caused by auto-immune thyroiditis. The presence of a hypothyroidism should be considered more often and a TSH examination should be run. Normal TSH levels exclude a primary hypothyroidism. Increased TSH levels in conjunction with lowered T4 levels prove the diagnosis. If a secondary form is suspected, complete pituitary diagnostics are mandatory. The substitution therapy is carried out with a medium dosage of levothyroxine, 2.0 micrograms/kg body weight per day. The appropriate dosage should be established slowly using small initial dosages. This is especially important in older patients and in those suffering from coronary disorders. For younger patients and those with a shorter history, a more immediate adjustment is possible. During gravidity, the hormone requirement increasing by 40% must be taken into consideration. The therapeutic effect is shown by the clinic as well as by the TSH level. Overdosage will lead to a reversible appearance of thyreoitoxicosis factitia and require re-adjustment of the dosage. A physiological dosage does not have negative consequences on the bone metabolism. Transitory corrections are possible although a continuous substitution is necessary most of the time. Regular checks must be made as the therapy may be discontinued in 40% of the cases. In case of subclinical hypothyroidism, an indication for treatment does not exist in all patients. However, treatment is indicated if there is a high risk for developing a permanent form of hypothyroidism or if additional findings exist possibly linked to subclinical hypothyroidism. This would make a hormone substitution necessary. In case of doubt, a probatory therapy can be initiated and discontinued after 6-12 months when there is no therapeutic effect.