Equis ISSN 2398-2977

Endocrine: testosterone assay

Contributor(s): Annalisa Barrelet, Graham Munroe, Janice Sojka, Han van der Kolk

Overview

  • Testosterone is secreted by the Leydig cells in the testes under the influence GnRH secretion from the hypothalamus via the production of luteinizing hormone from the pituitary gland.
  • Testosterone exerts a negative feedback on GnRH.
  • Steroid hormone responsible for spermatogenesis, development of male genitalia, descent of the testes in the fetus or neonate, further growth and development of the genitalia and accessory sex glands at puberty.
  • It stimulates the CNS in producing libidio, male sexual responses, and secondary sexual characteristics.
  • There are significant seasonal changes in plasma testosterone concentration (highest levels in May and lowest levels in November-January in northern hemisphere). There is also a diurnal rhythm with higher levels at 6 am than at 6 pm.
  • There is wide fluctuation in testosterone levels within and among stallions, and therefore "one-off" samples need to be interpreted with care.

Sampling

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Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Reimers T J et al (1991) Effects of hemolysis and storage on quantification of hormones in blood samples from dogs, cattle and horses. Am J Vet Res 52 (7), 1075-80 PubMed.
  • Cox J E, Redhead P H & Dawson F E (1986) Comparison of the measurement of plasma testosterone and plasma estrogens for the diagnosis of cryptorchidism in the horse. Equine Vet J 18 (3), 179-82 PubMed.
  • Stabenfeldt G H & Hughes J P (1980) Diagnostic endocrinology of the horse. Vet Clin North Am (Large Anim Pract) (2), 253-265 PubMed.


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