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Test ID: TSH
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Thyroid Stimulating Hormone
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Useful For
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To help diagnose thyroid disorders and to monitor treatment of hypothyroidism and hyperthyroidism
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Method name and description
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Electrochemiluminescence Immunoassay (ECLIA): Sandwich principle
Electrochemiluminescence immunoassay (ECLIA) intended for use on the cobas e 801 immunoassay analyzer. Patient specimen, biotinylated monoclonal TSH‑specific antibodies, and a monoclonal TSH‑specific antibody labeled with a ruthenium complex react to form a sandwich complex. After addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell II M. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier. Results are determined via a calibration curve which is instrument specifically generated by 2‑point calibration and a master curve.
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Clinical information
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TSH is formed in specific basophil cells of the anterior pituitary and is subject to a circadian secretion sequence.The hypophyseal release of TSH is the central regulating mechanism for the biological action of thyroid hormones. TSH. The determination of TSH serves as the initial test in thyroid diagnostics. Even very slight changes in the concentrations of the free thyroid hormones bring about much greater opposite changes in the TSH level. (Roche Cobas TSH package insert ; Roche Diagnostic Corp., Indianapolis, IN)
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Aliases
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Thyroid Stimulating Hormone , TSH, Thyrotropin
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Specimen type / Specimen volume / Specimen container
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Specimen type: Serum, Plasma
Minimum volume of sample: 1 mL
Serum: Plain tube (red or yellow top)
Plasma: Li‑heparin tube
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Collection instructions / Special Precautions / Timing of collection
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Collect blood by standard venipuncture techniques as per specimen requirements. When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.
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Storage and transport instructions
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Storage: 8 days at 20 – 25°C
14 days at 2 – 8°C;
24 months at ‑20 °C (± 5 °C)
Transport: 2-25°C
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Specimen Rejection Criteria
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Grossly hemolyzed, icteric and lipemic samples, wrong collection container, insufficient sample and heat‑inactivated samples.
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Biological reference intervals and clinical decision values
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Age
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Reference interval mIU/L
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From
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To
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From
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To
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0 Days
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5 Days
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0.7
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15.2
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5 Days
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2 M
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0.7
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11
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2 M
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11 M
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0.7
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8.4
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11 M
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5 Y
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0.7
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6.0
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5 Y
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10 Y
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0.6
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4.8
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10 Y
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19 Y
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0.5
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4.3
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19 y
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150Y
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0.3
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4.2
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Interpretative comment:
As per ATA guidelines 2017, for the typical patient in early pregnancy the TSH upper reference limit is 4.0 mIU/L and the lower limit of the reference range is significantly lower than the non-pregnant reference range.
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Turnaround time / Days and times test performed / Specimen retention time
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Daily (24/7)
Turn-around time:
Routine: One working day
Specimen Retention: 4 days
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