Seasonal Variations in Sex Steroids in a Young Male Population and Their Relationship with Plasma Levels of Vitamin D.

PURPOSE: Vitamin D (VD) acts on sperm motility, capacitation and survival but its role in steroidogenesis is less clear. Aims: To analyze seasonal variations in sex steroids and VD in a healthy male population. MATERIALS AND METHODS: Twenty-nine healthy males, 34.0±4.8 years were included. Blood collection in winter (W) and summer (S) was performed to measure: 25OHD, total testosterone (TT), free testosterone (FT), estradiol (E2), luteinizing hormone (LH), and sex hormone binding globulin (SHBG). Testosterone/estradiol (T/E2) ratio was calculated. RESULTS: In W, lower levels of 25OHD: 18.8±7.2 ng/mL vs. 38.8±11.9 ng/mL (p<0.0001) and LH: 3.5±1.2 mU/mL vs. 3.9±1.5 mU/mL (p=0.05), and higher levels of TT: 501.9±157.7 ng/dL vs. 405.0±128.0 ng/dL (p=0.0003), FT: 11.8±4.1 ng/dL vs. 10.2±3.7 ng/dL (p=0.017), SHBG: 28.5±10.9 nmol/L vs. 23.6±7.9 nmol/L (p=0.002) and T/E2 ratio: 30.7±19.7 ng/dL/pg/mL vs. 17.3±3.6 ng/dL/pg/mL (p=0.0015) with no variation in E2 levels were observed. A positive correlation between 25OHD and E2 (r=0.28, p=0.04) and negative correlations between 25OHD and TT (r=-0.27, p=0.049), 25OHD and FT (r=-0.32, p=0.01), and 25OHD and T/E2 (r=-0.44, p=0.0008) were found. CONCLUSIONS: In healthy young male population, seasonal variations were observed in 25OHD and LH levels (higher in S) and in TT, FT, SHBG levels, and T/E2 (higher in W). Lower values of TT and FT in S are accompanied by higher levels of LH, which rules out a central mechanism for lowering testosterone. 25OHD negatively correlated with TT, FT, and T/E2 and positively correlated with E2, suggesting a relationship between VD status and changes in gonadal steroids.

Assessment of the utility of measuring Thyroglobulin mRNA levels by Quantitative Real-Time PCR in the follow-up of differentiated thyroid cancer patients.

INTRODUCTION: The determination of thyroglobulin levels by immunoassay and imaging studies is subject to interference by antithyroglobulin antibodies in up to 30% of cases, suggesting a need to find alternative methods for the follow-up of a significant number of thyroid cancer patients. OBJECTIVES: Assess the sensitivity, specificity, and predictive values of thyroglobulin messenger RNA levels measured by quantitative Real Time-PCR (qRT-PCR) in the blood of patients followed for differentiated thyroid cancer. METHODS: This is a prospective study of Tg-mRNA levels measured with qRT-PCR. A peripheral blood sample was taken in patients with excellent response (69) and with structural incomplete response to treatment (23). Results were analysed using the Unity Real-Time program and expressed as fg/µg RNA. A Receiver Operating Characteristic curve was constructed to assess Tg-mRNA cut-off values. RESULTS: Tg-mRNA levels were not significantly different between the group with excellent response [0.10 fg/µg RNA (0.08-0.17)] and the group with incomplete structural response [0.133 fg/µg RNA (0.07-0.33)] (P < .06). Test sensitivity was 69.6%, specificity was 59.4%, negative predictive value was 85.4% and positive predictive value 36.4% CONCLUSIONS: Our experience shows that this technique could be useful as a rule-out test in selected cases, but its low sensitivity and specificity preclude its usefulness as a first-line test.

Assessment of the utility of measuring Thyroglobulin mRNA levels by Quantitative Real-Time PCR in the follow-up of differentiated thyroid cancer patients. / Evaluación de la utilidad de medir los niveles de ARN mensajero de tiroglobulina por PCR cuantitativa en tiempo real para el seguimiento de pacientes con cáncer diferenciado de tiroides.

INTRODUCTION: The determination of thyroglobulin (Tg) levels by immunoassay is subject to interference by antithyroglobulin antibodies in up to 30% of cases, suggesting a need to find alternative methods for the follow-up of a significant number of thyroid cancer patients. OBJECTIVES: Assess the sensitivity, specificity, and predictive values of thyroglobulin messenger RNA (Tg-mRNA) levels measured by quantitative Real Time-PCR (qRT-PCR) in the blood of patients followed for differentiated thyroid cancer. METHODS: This is a prospective study of Tg-mRNA levels measured with qRT-PCR. A peripheral blood sample was taken in patients with excellent response (n=69) and with structural incomplete response to treatment (n=23). Results were analysed using the Unity Real-Time program and expressed as fg/µg RNA. A Receiver Operating Characteristic curve was constructed to establish Tg-mRNA cut-off values. RESULTS: Tg-mRNA levels were not significantly different between the group with excellent response [0.10fg/µg RNA (0.08-0.17)] and the group with incomplete structural response [0.133fg/µg RNA (0.07-0.33)] (p<0.06). Test sensitivity was 69.6%, specificity was 59.4%, negative predictive value was 85.4% and positive predictive value was 36.4%. CONCLUSIONS: Our experience shows that this technique could be useful as a rule-out test in selected cases, but its low sensitivity and specificity preclude its usefulness as a first-line test.