[Diagnostic significance of immunoradiometric serum TSH determination]

TSH measurements using sensitive TSH-IRMA method makes differentiation of euthyroidism and hyperthyroidism possible without TSH stimulation after TRH. TSH-basal values less than 0.1 mU/L proof pituitary TSH suppression (clinical overt and latent hyperthyroidism, thyroid hormone therapy etc.). TSH-basal values between 0.4 and 4.0 mU/L are found in euthyroidism. TSH-basal values greater than 4.0 mU/L indicate latent or manifest hypothyroidism. With basal TSH values between 0.1 and 0.4 mU/L (borderline values between euthyroidism and "relative pituitary hormone excess") a TRH-test ist still necessary as it is not possible to predict stimulated TSH values from basal TSH concentrations with adequate accuracy. TSH measurements using sensitive IRMA methods may be recommanded as a screening test of thyroid function.