Laboratory tests in endocrinology provide quick results, and modern technology is easy to use with reasonable costs. Availability and widespread use of immunoassay-based hormone tests has also recognized analytical problems, differences between results of laboratories and manufacturers, affecting comparison of test results and impairing quality of health care. International professional societies and workgroups undertake activities to harmonize measurement methods and recommend referent methods, define hormone forms of diagnostic importance, reference (standard) material for calibration and traits for referent populations for reference intervals. Mass spectrometry is mostly the reference method, and immunoassays need to be calibrated according to reference material and reference method. Calibration against reference method should improve the performance of automated immunoassays.
The most common problems and limitations of immunoassays for hormone measurement will be discussed which may cause unexpected results or incongruence with clinical presentation. Some of these problems can be solved by the laboratory professional. Future for laboratory endocrinology seems to be better with possibilities of availability and cost-effectiveness of mass spectrometry, providing a more accurate and precise result in hormone measurement. Another interesting option in hormone measurement is point-of-care technology for diagnosis in doctors’ office, fieldwork and during surgery for confirmation of successful operation. Awareness of limitations of routine measurement methods has introduced “assay problem” as differential diagnosis.
Clinical aspect of hormone tests will be discussed on two appropriate examples, challenges in the interpretation of TSH tests in adults, and evaluation of hormone tests in diagnosis and monitoring of congenital adrenal hyperplasia.