[Thyroid dysfunction in old age]

Thyroid dysfunctions are common endocrine disorders. With an increasing number of older persons in European societies, the number of older patients affected will also rise. The physiology of thyroid hormones and their regulation change with increasing age. The age-dependent increase of thyroid stimulating hormone (TSH) is clinically most relevant, but many laboratories do not provide age-specific reference ranges. Older patients also have more comorbidities and thyroid dysfunctions will have a negative impact on many of these, in particular on cardiovascular disorders. While there are clear indications to treat overt hyperthyroidism and hypothyroidism, treatment recommendations for subclinical thyroid dysfunctions differ depending on the patient's age. The European Thyroid Association suggests a TSH level of 0.1 mU/l for patients with subclinical hyperthyroidism older than 65 years as threshold. A TSH level < 0.1 mU/l is a clear indication for treatment while concentrations > 0.1 mU/l are relative treatment indications. Patients older than 65 years with subclinical hypothyroidism and a TSH level > 10 mU/l should also be treated, in particular when cardiovascular comorbidities are present. Levothyroxine treatment has to be monitored on a regular basis, as overdosing is also harmful. For patients with TSH concentrations between 7 and 10 mU/l there is no clear indication to initiate a levothyroxine treatment, as they do not have a clearly elevated mortality and morbidity, also quality of life does not improve.