ISSN 2398-2942      

Thyroid: TSH assay

icanis
Contributor(s):

David Bruyette

Roger Powell

Synonym(s): Thyroid stimulating hormone assay


Overview

  • Thyrotropin releasing hormone (TRH, from the hypothalamus) stimulates production of TSH from the anterior pituitary to regulate the synthesis and secretion of thyroxine (T4) and tri-iodothyronine (T3)  Hypothalamic-pituitary-thyroid axis diagram. This is a negative feedback system, the released (free) T4 and T3 inhibiting further release of TSH.

Sampling

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Tests

Methodologies

  • Requires canine specific or validated assays.
  • Varied Fluorescent and Enzymatic ImmunoAssays (EIAs) Enzyme linked immunosorbent assay (ELISA) or RadioImmunological Assays (RIAs).
  • Laboratory testing should use external quality assurance schemes to validate performance, eg VEEEQAS / ESVE.

Availability

  • Most commercial laboratories (EIAs), few reference laboratories (RIAs).

Validity

  • Varies with study, test methodology and reference method used, historically often relative to dynamic TSH stimulation testing or thyroid gland histopathology.

Sensitivity

  • 75-87%.

Specificity

  • 82-100%. 
  • 10-20% sick-euthyroid dogs have increased TSH.

Predictive value

  • Positive predictive value 55-75% (depending on test and which group of dogs are being tested).
  • Negative predictive value 90-100% (depending on test and which group of dogs are being tested.

Technique (intrinsic) limitations

  • Cannot accurately distinguish low and normal concentrations of cTSH.

Technician (extrinsic) limitations

  • Minimal risk of technician errors.

Result Data

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Dixon R M &Mooney C T (1999) Evaluation of serum free thyroxine and thyrotropin concentrations in the diagnosis of canine hypothyroidism. JSAP 40 (2), 72-78.
  • Panclera D L (1999) Is it possible to diagnose hypothyroidism? JSAP 40 (4), 152-157.
  • Iversen L, Hoier R, Jensen A L et al (1998) Evaluation of the analytical performance of an enzyme immunometric assay (EIA) designed to measure endogenous thyroid-stimulating hormone (TSH) in canine serum samples. JAVMA 45, 93-98.
  • Bruner J M, Scott-Moncrieff C R & Williams D A (1998) Effect of time of sample collection on serum thyroid-stimulating hormone concentrations in euthyroid and hypothyroid dogs. JAVMA 212, 1572-1575.
  • Peterson M E, Melian C & Nichols R (1997) Measurement of serum total thyroxine, triodothyronine, free thyroxine and thyrotropin concentrations for diagnosis of hypothyroidism in dogs. JAVMA 211, 1396-1402.
  • Ramsey I K, Evans H & Herrtage M E (1997) Thyroid stimulating hormone and total thyroxine concentrations in euthyroid, sick euthyroid and hypothyroid dogs. JSAP 38(12), 540-545.
  • Dixon R M, Graham P A & Mooney C T (1996) Serum thyrotropin concentrations - a new diagnostic test for canine hypothyroidism. Vet Rec 138, 594-595.

Other sources of information

  • Information available from commercial laboratories who perform the test.

MEMBER BENEFIT

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code