Indirect estimation of reference intervals for thyroid parameters using advia centaur XP analyzer.

Background: The aim of this study was to determine the reference intervals (RIs) for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and FT3/FT4 ratio using indirect methods. Methods: We analyzed 1256 results TSH, FT4 and FT3 collected from a laboratory information system between 2017 and 2021. All measurements were performed on a Siemens ADVIA Centaur XP analyzer using the chemiluminescent immunoassay. We calculated the values of the 2.5th and 97.5th percentiles as recommended by the IFCC (CLSI C28-A3). Results: The RIs derived for TSH, FT4, FT3 and FT3/FT4 ratio were 0.34-4.10 mIU/L, 11.3-20.6 pmol/L, 3.5-6.32 pmol/L and 0.21-0.47, respectively. We found a significant difference between calculated RIs for the TSH and FT4 and those recommended by the manufacturer. Also, FT3 values were significantly higher in the group younger than 30 years relative to the fourth decade (5.26 vs. 5.02, p=0.005), the fifth decade (5.26 vs. 4.94, p=0.001), the sixth decade (5.26 vs. 4.87, p<0.001), the seventh decade (5.26 vs. 4.79, p<0.001) and the group older than 70 years old (5.26 vs. 4.55, p<0.001). Likewise, we found for TSH values and FT3/FT4 ratio a significant difference (p <0.001) between different age groups. Conclusions: The establishing RIs for the population of the Republic of Srpska were significantly differed from the recommended RIs by the manufacturer for TSH and FT4. Our results encourage other laboratories to develop their own RIs for thyroid parameters by applying CLSI recommendations.

Direct Estimation of Reference Intervals for Thyroid Parameters in the Republic of Srpska.

BACKGROUND: The aim of this study was to determine the reference values for thyrotropin (TSH), thyroid hormones (total and free thyroxine, T4 and fT4; total and free triiodothyronine, T3 and fT3), thyroglobulin (Tg) and thyroid antibodies (thyroid peroxidase, TPOAb and thyroglobulin antibody, TgAb) in the population of the Republic of Srpska. METHODS: A total of 250 euthyroid subjects were enrolled in this study. A direct method for choosing reference subjects was used to establish reference intervals. The hormones and thyroid antibodies were measured by an electrochemiluminescence immunoassay method (ECLIA, Roche Diagnostics, Mannheim, Germany). We calculated the reference intervals by MedCalc, version 12.1.4.0 (MedCalc software, Belgium) as recommended by the IFCC (CLSI C28-A3). RESULTS: Using guidelines recommended by the National Academy of Clinical Biochemistry (NACB) and based on standard statistical approaches, the reference intervals derived for TSH, fT4, T4, fT3, T3 were 0.75-5.32 mIU/L, 12.29-20.03 pmol/L, 73.49-126,30 nmol/L, 4.11-6.32 pmol/L, 1.15-2.32 nmol/L and for Tg, TPOAb, TgAb were 3.63-26.00 µg/L, <18.02 mIU/L, < 98.00 mIU/L, respectively. We found a significant difference (p<0.05) in TSH and fT3 values between different age groups as well as in T4, fT4 and fT3 values between ge nder groups. CONCLUSIONS: The established reference values for the population of the Republic of Srpska were significantly different from the values recommended by the manufacturer of reagents (Roche Diagnostics). Our results showed that a laboratory needs to establish its own reference values in order to set up a proper diagnosis, as well as to treat patients successfully.

The impact of time of sample collection on the measurement of thyroid stimulating hormone values in the serum.

OBJECTIVE: The aim of our research is to determine whether the time of blood sampling and fasting of patients have an impact on TSH values. DESIGN AND METHODS: A total of 198 participants were enrolled in this study and classified into five groups: A--the first sample collection for TSH measurement was taken between 7:00 and 8:00 a.m. at fasting and the second after 140 min without food intake; B--between 7:00 and 8:00 a.m. at fasting and the second after 140 min with food intake; C--between 7:00 and 8:00 a.m. at fasting the previous day and the second one between 7:00 and 8:00 a.m. at fasting the following day; D--between 9:00 and 10:00 a.m. at fasting the previous day and the second one between 9:00 and 10:00 a.m. at fasting the following day, and E--between 9:00 and 10:00 a.m. at fasting the previous day and the second one between 7:00 and 8:00 a.m. on the following day. Serum TSH concentration was measured by electrochemiluminescence immunoassay (ECLIA, Roche Diagnostics, Mannheim, Germany). RESULTS: TSH values (mIU/L) were in group A: 2.50 (2.20-2.81) first samples, 1.74 (1.52-1.96) second samples, p<0.001; B: 2.11 (1.52-2.72) first samples, 1.56 (1.13-1.81) second samples, p<0.001; C: 2.60 (2.28-2.91) first samples, 2.23 (1.92-2.53) second samples, p<0.001; D: 1.80 (1.48-2.11) first samples, 1.77 (1.44-2.09) second samples, p<0.597; and E: 1.32 (1.11-2.16) first samples, 1.67 (1.48-2.93) second samples, p<0.001. CONCLUSION: The time of sample collection must be standardised for the purpose of standardisation and harmonisation of TSH measurements.

Atorvastatin in stable angina patients lowers CCL2 and ICAM1 expression: pleiotropic evidence from plasma mRNA analyses.

OBJECTIVE: Statin pleiotropy is still an evolving concept, and the lack of clarity on this subject is due at least in part to the lack of a definitive biomarker for statin pleiotropy. Using plasma mRNA analysis as a novel research tool for the non-invasive in vivo assessment of gene expression in vascular beds, we hypothesised that atorvastatin lowers the plasma mRNA level from statin pleiotropy-target genes, and the reduction is independent of the reduction of low-density lipoprotein cholesterol (LDL-C). DESIGN AND METHODS: Forty-four patients with stable angina received atorvastatin therapy (20 mg/day, 10 weeks). Plasma chemokine (C-C motif) ligand 2 (CCL2) and intercellular adhesion molecule-1 (ICAM1) mRNA levels and their protein concentrations (MCP-1, sICAM-1) were analysed before and after the treatment. Plasma vascular adhesion molecule-1 (sVCAM-1) concentrations were also analysed. RESULTS: Atorvastatin lowered plasma mRNA levels (CCL2: -31.76%, p=0.037; ICAM1: -34.09%, p<0.001) and MCP-1 protein concentration (-18.88%, p=0.008) but did not lower sICAM-1 and sVCAM-1 protein concentrations, and the decreases appeared to be independent from the lowering of LDL-C. The plasma mRNA levels correlated with their protein concentrations following statin treatment only. CONCLUSION: Our results significantly strengthen the clinical evidence in support of statin pleiotropy. Furthermore, this unique simultaneous measurement of plasma mRNAs and their protein concentrations offers an advanced non-invasive in vivo assessment of the circulation pathology.