[The limit of reference range of TSH: long-term discussion and possibilities of modern diagnostic.]

The review considers problem of upper limit of reference interval of TSH that is discussed predominantly by endocrinologists out of laboratory community. The common values of 0.4-4.0 mE/l combine as a matter of fact two ranges: zone of practically full wellbeing (0.4-2.5 mE/l) and zone of latent pathology and/or high possibility of development of clinically significant hypothyroidism (2.5-4.0 mE/l). At one time, the proposal to diminish upper limit of reference interval provoked many discussions and on balance received no approval. However, no unanimity concerning this issue is still to be achieved. The article discusses data forcing medical specialists to be wary of values of TSH in the range of 2.5-4.0 mE/l. At the same time, the question is putted concerning suitability of using population reference intervals in the case of both of TSH and number of other indices of laboratory diagnostic.