Valoración de la función tiroidea durante la gestación: intervalos de referencia de tirotropina y tiroxina no unida a proteína durante el primer trimestre / Evaluation of testosterone levels through distinct analytic methods in healthy men

Objetivos Estudiar los rangos de normalidad de testosterona en varones jóvenes sanos y comparar los resultados de los distintos métodos analíticos utilizados. Material y métodos Se incluyeron 20 hombres sanos con una edad media de 24,5 años (desviación estándar (DE): 5,04), un índice de masa corporal (IMC) medio de 23,8% (DE: 3,3). Se determinaron las concentraciones de testosterona total (TT) mediante inmunoquimioluminiscencia (ICLA), de testosterona libre (TL) mediante radioinmunoensayo (RIA), y se calculó la testosterona libre calculada (TLc) y la testosterona biodisponible (TB) mediante la fórmula de Vermeulen. Se midieron las concentraciones séricas de lutropina (LH), folitropina (FSH) y proteína ligadora de hormonas sexuales (SHBG) por método inmunorradiométrico (IRMA).Resultados Las concentraciones medias de TT fueron de 20nmol/l (DE 4,96), las de TL de 0,054nmol/l (DE 0,01), los de TLc de 0,3834nmol/l (DE 0,09) y los de TB de 9,9nmol/l (DE: 2,8 ). No se encontró correlación entre las concentraciones de testosterona medidos por los distintos métodos, excepto entre TL y TLc (r=0,662; p<0,003) y entre TLc y TB (r=0,979; p<0,0001). Existe una asociación inversa entre IMC y las concentraciones de testosterona total (r: −0,52; p<0,017).Conclusiones Es necesario establecer el intervalo de normalidad para la testosterona en hombres jóvenes sanos en función del método analítico utilizado (AU)

Plasma testosterone concentrations are essential for the diagnosis of several causes of hypogonadism, including late-onset hypogonadism. Defining the normal range for testosterone concentrations poses certain difficulties due to the changes that occur with age and the variability of the different analytical methods used. Objectives To study normal ranges of testosterone in healthy young men and to compare the results of distinct analytical methods. Material and methods We recruited 20 healthy men with a mean age of 24.5 years (standard deviation (SD): 5.04) and a mean body mass index (BMI) of 23.8% (SD: 3.3). Total testosterone (TT) was measured by immunochemiluminescence (ICLA) and free testosterone (FT) by radioimmunoassay (RIA). Calculated free testosterone (FTc) and bioavailable testosterone (BT) were calculated using Vermeulen's formula. Serum lutropin (LH), follitropin (FSH) and sex hormone binding globulin (SHBG) were measured by immunoradiometric assays (IRMA).Results The mean concentrations were 20nmol/l (SD: 4.96) for TT, 0.054nmol/L (SD: 0.01) for FT, 0.3834nmol/L (SD: 0.09) for FTc and 9.9nmol/L (SD: 2.8) for BT. There was no correlation between testosterone measured by different methods other than an association between FT and FTc (r=0.662, p<0.003) and between FTc and BT (r=0.979, p<0.0001). An inverse correlation was found between BMI and TT concentrations (r: −0.52, p<0.017).Conclusions The normal range for testosterone in healthy young men should be established in each laboratory based on the analytical method used (AU)

[Evaluation of thyroid function during pregnancy: first-trimester reference intervals for thyroid-stimulating hormone and free thyroxine]. / Valoración de la función tiroidea durante la gestación: intervalos de referencia de tirotropina y tiroxina no unida a proteína durante el primer trimestre.

BACKGROUND AND OBJECTIVES: The physiological changes that occur during pregnancy affect the physiology of the thyroid gland. Consequently, interpretation of thyroid function markers during pregnancy requires trimester-specific reference intervals. The aims of our study were to: 1) establish first-trimester reference intervals for biochemical markers of thyroid function [thyroid-stimulating hormone (TSH) and free thyroxine (T4)] and 2) to establish the prevalence of autoimmune thyroid disease in pregnant women resident in Cartagena (Murcia, Spain). PATIENTS AND METHOD: A total of 441 women between weeks 11 and 13 of pregnancy were included in this study. A blood sample was extracted from all women to measure TSH, free T4 and antithyroid antibodies. Reference intervals for TSH and free T4 were determined in 400 pregnant women without autoimmune thyroid disease or known thyroid disease. RESULTS: Autoimmune thyroid disease was detected in 23 pregnant women (5.2%) who showed TSH levels higher than those in pregnant women without thyroid autoimmunity. First-trimester reference intervals were as follows: TSH: 0.130-3.710 mUI/L; free T4: 0.89-1.50 ng/dL. These reference intervals differed from the non-pregnant reference intervals used in our laboratory. CONCLUSIONS: The reference intervals established are useful to evaluate thyroid function in women between 11 and 13 weeks of pregnancy. Interpretation of thyroid function requires intervals established in a reference population without autoimmune thyroid disease and with the methodology usually used to analyze these markers.