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  • Print publication year: 2015
  • Online publication date: June 2015

8 - Regulation of hormone levels in the bloodstream

Summary

As illustrated in Figures 6.5 and 6.11, pituitary (LH, FSH and ACTH) and steroid (cortisol) hormone levels in the bloodstream fluctuate dramatically over short periods of time (minutes to hours). In addition, hormones such as GH, ACTH and melatonin show marked circadian variations in their secretion patterns (Figure 6.5). These patterns are physiologically important; for example, we saw in the case of LH secretion, a continuous release, rather than a pulsatile secretion, will not stimulate the ovaries or testes correctly (Figure 7.4). In other words, fertility is dependent on an appropriate pulsatile LH signal reaching the gonads. This principle might be generally applicable to all pituitary hormone secretions. The measurement, or assay, of hormone levels is therefore an important clinical goal, as well as a crucial aid in understanding how hormone levels in blood are regulated and how the neuroendocrine system functions in health and disease. This chapter thus begins with an examination of the methods for measuring hormone levels in the circulation.

Analysis of hormone levels

The level of a circulating hormone can be measured directly in blood samples or estimated by measuring hormone levels in the saliva, urine or feces, measuring urinary metabolites, or by using bioassays. The determination of glucocorticoids levels in hair, for example, is a way to detect long-term exposure to stress.

8.1.1 Direct measurement of circulating hormones

In the past 20 years, there have been striking changes in the analytical techniques used to estimate hormone levels. Until recently, the benchmark in determination of hormone levels was the radioimmunoassay. However, this method, employing antibodies specific to each hormone, and radioactively labeled hormones, is slow, labor-intensive and raised safety problems in the use and disposal of radioactive materials. It is now routine to analyze hormone levels using rapid and automated chemiluminescent or immunometric assays that produce data in a matter of hours, rather than days.

A widely used assay is the Enzyme-linked Immunosorbent Assay (ELISA).

Arendt, J. (2006). “Melatonin and human rhythms,” Chronobiol Int 23, 21–37.
Besser, G. M. and Thorner, M. O. (2002). Comprehensive Clinical Endocrinology, rd edn. (St. Louis, MO: Mosby).
Chaudhri, O. B., Salem, V., Murphy, K. G. and Bloom, S. R. (2008). “Gastrointestinal satiety signals,” Annu Rev Physiol 70, 239–255.
Dunger, D. B., Villa, A. K., Matthews, D. R., Edge, J. A., Jones, J., Rothwell, C.et al. (1991). “Pattern of secretion of bioactive and immunoreactive gonadotrophins in normal pubertal children,” Clin Endocrinol (Oxf) 35, 267–275.
Gooley, J. J., Chamberlain, K., Smith, K. A., Khalsa, S. B., Rajaratnam, S. M., Van Reen, E.et al. (2010). “Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans,” J Clin Endocrinol Metab 96, 463–472.
Henley, D. E., Leendertz, J. A., Russell, G. M., Wood, S. A., Taheri, S., Woltersdorf, W. W.et al. (2009). “Development of an automated blood sampling system for use in humans,” J Med Eng Technol 33, 199–208.
Koch, B. C. P., Nagtegaal, J. E., Kerkhof, G. A. and ter Wee, P. M. (2009). “Circadian sleep-wake rhythm disturbances in end-stage renal disease,” Nat Rev Nephrol 5, 407–416.
McNeilly, A. S., Robinson, I. C., Houston, M. J. and Howie, P. W. (1983). “Release of oxytocin and prolactin in response to suckling,” Br Med J (Clin Res Ed) 286, 257–259.
McWhinney, B. C., Briscoe, S. E., Ungerer, J. P. and Pretorius, C. J. (2010). “Measurement of cortisol, cortisone, prednisolone, dexamethasone and 11-deoxycortisol with ultra high performance liquid chromatography-tandem mass spectrometry: application for plasma, plasma ultrafiltrate, urine and saliva in a routine laboratory,” J Chromatogr B Analyt Technol Biomed Life Sci 878, 2863–2869.
Melmed, S. (2009). “Acromegaly pathogenesis and treatment,” J Clin Invest 119, 3189–3202.
Meyer, J. S. and Novak, M. A. (2012). “Minireview: hair cortisol: a novel biomarker of hypothalamic-pituitary-adrenocortical activity,” Endocr 153, 4120–4127.
Mitchell, F. (2012). “Mass spectrometry ‘gold standard’ for measuring steroid sex hormones?”Nat Rev Endocr 8, 320.
Murphy, P. R., Friesen, H. G., Brown, R. E. and Moger, W. H. (1989). “Verification of NB2 lymphoma cell bioassay for the measurement of plasma and pituitary prolactin in the Mongolian gerbil (Meriones unguiculatus),” Life Sci 45, 303–310.
Nussey, S. S. and Whitehead, S. A. (2001). Endocrinology: An Integrated Approach (Oxford: Bios Scientific Publishers), www.ncbi.nlm.nih.gov/books/NBK20.
Plant, T. M. (1986). “Gonadal regulation of hypothalamic gonadotropin-releasing hormone release in primates,” Endocr Rev 7, 75–88.
Soldin, S. J. and Soldin, O. P. (2009). “Steroid hormone analysis by tandem mass spectrometry,” Clin Chem 55, 1061–1066.
Squire, L. R., Berg, D. E., Bloom, F. E., du Lac, S., Ghosh, A. and Spitzer, N. C. (2008). Fundamental Neuroscience, rd edn. (London: Academic Press).
Stanczyk, F. Z. and Clarke, N. J. (2014). “Measurement of estradiol – challenges ahead,” J Clin Endocr Metab 99, 56–58.
Tractenberg, R. E., Jonklaas, J. and Soldin, S. J. (2010). “Agreement of immunoassay and tandem mass spectrometry in the analysis of cortisol and free t4: interpretation and implications for clinicians,” Int J Anal Chem 2010, article no. 234808.
Widmaier, E. P., Raff, H. and Strang, K. T. (2010). Vander's Human Physiology: The Mechanisms of Body Function, th edn. (New York: McGraw-Hill).
Xu, C., Roepke, T. A., Zhang, C., Ronnekleiv, O. K. and Kelly, M. J. (2008). “Gonadotropin-releasing hormone (GnRH) activates the m-current in GnRH neurons: an autoregulatory negative feedback mechanism?”Endocr 149, 2459–2466.
Zerikly, R. K., Amiri, L., Faiman, C., Gupta, M., Singh, R. J., Nutter, B.et al. (2010). “Diagnostic characteristics of late-night salivary cortisol using liquid chromatography-tandem mass spectrometry,” J Clin Endocrinol Metab 95, 4555–4559.