Determinación del límite superior de referencia de TSH, en una población de individuos en la ciudad de México

Abstract

Context: The establishment of the reference intervals of thyrotropin (TSH) has changed during the last decades. This point performs vital importance, due to the fact that the TSH has a great sensibility, reflecting accurately the changes in the concentration of the thyroid hormones at tissue level. Objectives: To define the normal upper limit for the TSH in a reference population according to the NACB (National Academy of Clinical Biochemistry) criteria united to the ultrasonographic examination of the thyroid. Patients and Methods: The study was realized in volunteers without known thyroid disease. We recruited 456 individuals (18 to 66 years), the majority was a medical personnel of the hospital. To which a questionnaire was applied to define demographic information, family history, co-morbidities, administration of iodinated contrast material, drugs taken and underwent measurement of the thyroid hormones, thyroid antibodies, thyroid physical examination, thyroid ultrasound and record of the thyroid echogenicity. Results: Of 456 subjects, 199 H/256 M, the mean age of volunteers was 28.6±8.0, the prevalence of TPO-Ab was 9.3 % and 10.3 % Tg-Ab. The mean TSH for the total population was of 2.74±2.87 and the percentila 97.5 was of 7.57 mUI/L. The reference population was limited to 267 subjects (42 % was eliminated), the mean of this population was 2.11±1.71, the percentila 97.5 was of 6.09 mUI/L. Conclusions: The upper reference limit in this population is the highest found in similar epidemiological studies, especially if we consider that the population is young and the selection system has been strict. The possible explanations fall into speculation; more studies must be realized in our population.