文摘
| Figures/TablesFigures/Tables | ReferencesReferences
Summary
Diagnostic of thyroid dysfunction is largely based on TSH measurement in blood. Defining the upper reference limit of TSH values is of paramount importance to establish normal level of TSH. Ideally, accurate TSH measurement around the normal reference range should permit to determine which of the patients will undergo additional investigation and/or hormonal therapy. At present, there is a common agreement on the 0.4-4.0 mIU/L values but the upper limit range of TSH remains controversial. Work from the past 10 years has rather denied the proposal of lowering the threshold. TSH is a glycoprotein hormone for which the nature and circulating level may widely change depending on environmental (iodine intake and photoperiod) and physiological (age, sex, weight and ethnic origin) factors as well as on patient habits (smoking). In addition, the hormone is composed of multiple glycoforms, which display variable immunological behavior and thereby lead to altered TSH measurement. Therefore, this review aims at reinvestigating the biological significance of blood TSH values and at proposing how to reach improved accuracy in TSH testing.
