Elecsys 2010

Thyroid function included TSH, fT3, and fT4 levels were evaluated pre-radiotherapy and at each follow-up visit. The electrochemiluminescence method by Elecsys 2010 analyzer (Hitachi High Technology Corporation, Tokyo, Japan) was used, with the reference ranges of 0.27–4.20 μIU/mL, 3.1–6.8 pmol/L, and 12.0–22.0 pmol/L, respectively. The reproducibility of the three thyroid hormones tests was acceptable, and their coefficient variations ranged between 1.3% and 1.5%. After radiotherapy, thyroid hormones tests were performed every 3 months during the first year, every 6 months in the second to the fifth year and annually after that. Biochemical HT is TSH value > 4.20 μIU/mL with the low or normal level of fT4. Patients whose fT3 and fT4 were at low levels and with low or normal TSH level, would be diagnosed as central HT.

This descriptive cross-sectional study was done on 3158 pregnant women in Taleghani Hospital in Tehran, Shahid Beheshti University of Medical Sciences from October 2008-March 2012. For all pregnant women in the first prenatal care and during routine laboratory workup, screening of thyroid function was done by TSH level in endocrine laboratory in Taleghani Hospital by the chemiluminescent immunoassay (Elecsys 2010, Hitachi, Diamond, Japan). If TSH level was >2.5 mIU/L in the first trimester or TSH >3 mIU/L in the second or third trimester, free T4 measurement was done by chemiluminescent immunoassay to know whether it is subclinical or overt hypothyroidism. If serum FT4 was in the normal range (0.8-1.7 ng/dl) SCH was diagnosed and if below the normal range, OH was the diagnosis.
Their demographic (maternal age, gestational age, parity) and clinical details were collected as part of routine antenatal care and were recorded. We asked the women about personal and family history of thyroid disease. Duration of gestation was calculated from last menstrual period and verified by ultrasonography. The Ethical Committee of Shahid Beheshti University of Medical Sciences approved this study and informed consent was taken from all participants. SPSS software version 20 were used for data analysis including t test.

Insulin and C-peptide serum concentrations were measured using Elecsys Insulin Assay® and Elecsys C-Peptide Assay®, respectively, according to the manufacturer’s instructions (Roche Diagnostics, Germany) with electrochemiluminescence, on Elecsys 2010 analyzer (Hitachi High-Technologies Corporation, Japan). Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) index was then calculated based on the following formula: insulin concentration × fasting glycemia × 0.0555/22.5, with insulin concentration expressed in μIU/mL and fasting glycemia expressed in mg/dL.

The serum levels of bone turnover markers, osteocalcin (OC) and β-CrossLaps (β-CTx), were determined by using the N-MID Osteocalcin kit (Cobas-Roche, Switzerland) and β-CrossLaps kit (Cobas-Roche, Switzerland), respectively. OC and β-CTx were analysed with the electrochemiluminescence immunoassay “ECLIA” and immunoassay analyser Elecsys 2010 (Hitachi High-Technologies Corporation, Tokyo, Japan) according to the manufacturers’ instructions.