Establishment of reference values of markers of non-thyroidal illness syndrome on a state-of-the-art fully automated ABEI-based chemiluminescence system

Abstract Background Non-Thyroidal Illness Syndrome (NTIS), previously called Euthyroid Sick Syndrome has always been a diagnostic dilemma for Chemical Pathologists and treating physicians. Combination of four test i.e. Reverse Triiodothyronine (rT3), Free Triiodothyronine (fT3), Free Thyroxine (fT4) and Thyroid Stimulating Hormone (TSH) can be helpful to diagnose NTIS in critically ill patients. We need, however, to determine the reference values found in a reference population, free of any thyroidal as well as non-thyroidal illness. Methods and Materials Initially, 266 adult volunteers were included in the study from Mohi Uddin Islamic Medical College Mirpur AJ&K (MIMC) and Mohi Uddin Teaching Hospital Mirpur AJ&K (MOTH) after taking written informed consent. About 124 volunteers were selected (males 61; females 63) after exclusion of the volunteers with one or more of the exclusion criteria. Blood specimens were collected and analyzed for rT3, fT3, fT4 and TSH using Maglumi X8 (S nibe, China), an ABEI (N-(aminobutil)-N-(ethyl)-isoluminol) based analyzer at Pathology Laboratory MOTH. Results Reference values of rT3, fT3, fT4 and TSH were found to be 13.3 – 19.8 ng/dL (0.2 – 0.30 nmol/L); 2.65 - 4.15 pg/mL (4.08 - 6.39 pmol/L);10.6 - 16.2 pg/mL (13.64–20.84 pmol/L) and 0.43 - 3.98 μIU/mL (0.43 – 3.98 mIU/L), respectively. Conclusion Reference values determined in our own population should be used when diagnosing and monitoring NTIS and other thyroid disorders