Thyroid-Stimulating Hormone (TSH), serum or plasma

Alternate test name

TSH

Lab area

Clinical Biochemistry - General

Method and equipment

Equipment : Roche Cobas Pro e801

Method : Sandwich principle. Total duration of assay: 18 minutes.
▪ 1st incubation: 30 µL of sample, a biotinylated monoclonal TSH‑specific antibody and a monoclonal TSH‑specific antibody labeled with a ruthenium complex react to form a sandwich complex.
▪ 2nd incubation: 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 provided via the cobas link.

Expected turn-around time

STAT: 3 Hours Urgent: 6 Hours Routine: 24 Hours

Specimen type

Serum and plasma heparin

Specimen requirements

300 uL

Storage and transportation

Frozen

Shipping information

The Hospital for Sick Children

Rapid Response Laboratory

555 University Avenue, Room 3642

Toronto, ON

Canada

M5G 1X8

Phone: 416-813-7200

Toll Free: 1-855-381-3212

Hours: 7 days/week, 24 hours/day

Requisition

Thyroid-Stimulating Hormone (TSH), serum or plasma - requisition

Background and clinical significance

Human Thyroid Stimulating Hormone (TSH) or thyrotropin is a glycoprotein with a molecular weight of approximately 28,000 daltons, synthesized by the basophilic cells (thyrotropes) of the anterior pituitary. TSH stimulates the production and secretion of the metabolically active thyroid hormones, thyroxine (T4) and triiodothyronine (T3), by interacting with a specific receptor on the thyroid cell surface. T3 and T4 are responsible for regulating diverse biochemical processes throughout the body which are essential for normal development and metabolic and neural activity. Failure at any level of regulation of the hypothalamic-pituitary-thyroid axis will result in either underproduction (hypothyroidism) or overproduction (hyperthyroidism) of T4 and/or T3. Primary hyperthyroidism (e.g., Grave’s Disease, nodular goiter) is associated with high levels of thyroid hormones and depressed or undetectable levels of TSH.