Thyroid Function in Dolphins: Radioimmunoassay Measurement of Thyroid Hormones

doi:10.1016/S0007-1935(17)32994-9

British Veterinary Journal

Volume 135, Issue 1, January–February 1979, Pages 96-102

https://doi.org/10.1016/S0007-1935(17)32994-9 Get rights and content

SUMMARY

Serum samples from Atlantic Bottlenosed dolphins (Tursiops truncatus) were examined by radioimmunoassay for circulating thyroid hormones and the results compared with human values and standard curves. Values for dolphin T₄ and free T₄ index were twice those for human controls, but T₃ and THBC values were similar. The results are in agreement with earlier work using non-immune methods. Human radioimmune tests provide an indicator of thyroid function in the dolphin.

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Cited by (10)

Thyroid hormone concentrations in relation to age, sex, pregnancy, and perinatal loss in bottlenose dolphins (tursiops truncatus)
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Citation Excerpt :
Although a comparable hCG-like substance has not been confirmed in serum of pregnant dolphins (Bergfelt et al., 2012), preliminary results have indicated plasma concentrations of TBG to be higher in dolphins than in humans (Ridgway and Patton, 1971). In a subsequent study (Greenwood and Barlow, 1979), TBG was not successfully measured but analysis of thyroid hormone binding capacity as an indirect measure of TBG indicated results were comparable between dolphins and humans. The present study in dolphins was not designed to evaluate serum concentrations of TBG or other thyroid hormone binding proteins (i.e., TTR and albumin).
This study evaluated circulating concentrations of thyroid hormones in relation to age, sex, pregnancy status, and perinatal loss in bottlenose dolphins (Tursiops truncatus) under human care. A total of 373 blood samples were collected from 60 individual dolphins housed at nine aquariums/oceanariums. Serum concentrations of total and free thyroxine (T₄) and triiodothyronine (T₃) were analyzed with commercial RIA kits validated for use with dolphins. While the effect of age was indicated by higher (P < 0.0001) concentrations of total and free T₄ and T₃ in juveniles than adults, the effect of sex on thyroid hormones was inconclusive. The effect of pregnancy was indicated by higher (P < 0.035) total and free T₄ and T₃ during early pregnancy compared to non-pregnancy. For both successful and unsuccessful pregnancy outcomes, maternal concentrations of thyroid hormones were highest during early, intermediate during mid, and lowest during late pregnancy (P < 0.07 to P < 0.0001). Compared to live and thriving births, concentrations of total and free T₄ and total T₃ were lower (P < 0.08 to P < 0.001) in dolphins with perinatal loss. Lower concentrations ranged from 10% to 14% during early, 11% to 18% during mid, and 23% to 37% during late pregnancy. In conclusion, the effects of age, reproductive status and stage of pregnancy on thyroid hormone concentrations are necessary factors to take into account when assessing thyroid gland function. Since perinatal loss may be associated with hypothyroidism in dolphins, analysis of serum T₄ and T₃ should be considered for those dolphins that have a history of pregnancy loss.
Influences of biological variables and geographic location on circulating concentrations of thyroid hormones in wild bottlenose dolphins (Tursiops truncatus)
2011, General and Comparative Endocrinology
Citation Excerpt :
Limited information exists on the TH system of odontocetes (toothed whales, dolphins, and porpoises), especially in wild populations. Circulating concentrations of TH have been reported for several marine mammal species including bottlenose dolphins (Tursiops truncatus) [10,23,44,51,54,57]. However, none of these previous studies investigated how biological variables such as age, sex, and reproductive status, as well as geographic location, influence TH.
Thyroid hormones (TH) are key regulators of metabolism and development, yet our understanding of the variability in serum TH concentrations in free-ranging marine mammals is limited. Thus, we examined the interrelationships between TH and age, sex, reproductive status, geographic location, and ocean temperatures in wild bottlenose dolphins (Tursiops truncatus). Circulating concentrations of TH (total thyroxine (tT₄), free T₄ (fT₄), and total triiodothyronine (tT₃)) were determined in a total of 195 dolphins; 80 from the coastal waters of Charleston, South Carolina (CHS) and 115 from the Indian River Lagoon, Florida (IRL). Age had the most influence on circulating TH concentrations in dolphins at both sites with decreasing concentrations (p < 0.0001) observed with increasing age for all TH. No significant differences were found between males and non-reproductive females. Geographic location significantly influenced tT₄ and tT₃ concentrations; CHS dolphins had higher concentrations than IRL animals. These TH differences between CHS and IRL dolphins may be attributed to the colder year-round water temperature that CHS dolphins inhabit compared to IRL dolphins and could constitute an adaptive response to their colder environment. Results from this study highlight the importance of establishing reference values for dolphins in different geographic locations to support valid comparisons. This initial assessment provides a foundation of how biological and environmental variables could affect circulating TH in dolphins, which will help to elucidate the impacts of disease, pollution, and climate change on the thyroid hormone system of aquatic mammals.
Disruptive effects of persistent organohalogen contaminants on thyroid function in white whales (Delphinapterus leucas) from Svalbard
2011, Science of the Total Environment
Citation Excerpt :
The standard test protocols for these RIA kits were followed (DPC, 2005a,b,c,d). Because THs are highly conserved among vertebrate species, the RIA method developed for humans is commonly used in measuring marine mammals TH levels with acceptable results (Greenwood and Barlow, 1979; St Aubin, 2001; Braathen et al., 2004; Sørmo et al., 2005). However, since methods for measuring human TSH have been shown to be unsuccessful in detecting this hormone in beluga whales (St Aubin, 2001), we measured TSH levels in the present study using a solid-phase 125I immunoradiometric (IRMA) kit developed for canines (Cout-A-Count Canine TSH IRMA, Siemens Medical Solutions Diagnostics, Los Angeles, CA, USA).
We analysed levels of 56 organohalogen contaminants (OHCs) including brominated flame retardants, polychlorinated biphenyls (PCBs), and organochlorine pesticides in the blubber of white (beluga) whales (Delphinapterus leucas) from Svalbard, Norway (N = 12; 6 adults [5 males and 1 female] and 6 subadults [4 males and 2 females]) collected in 1996–2001. We also measured circulating levels of thyroid hormones (THs) and thyroid stimulating hormone (TSH) in the whales. The results confirm that OHC levels in these white whales are among the highest levels recorded in wildlife from Svalbard, and at the high end of the range when compared to white whales from the North American Arctic. A projection to latent structure (PLS) model (subadults and adult males grouped together) revealed that known or suspected thyroid disruptive contaminants (polybrominated diphenylether [PBDE]-28, -47, -99, -100, and -154, hexachlorobenzene [HCB], and PCB-105) were negatively correlated with circulating levels of total thyroxin (TT4), free T4 (FT4) and free triiodothyronine (FT3). Most of these negative relationships were also confirmed using partial correlations controlling for length (and thus age) of the whales. The positive correlations of TT4, FT4 and FT3 with hexabromocyclododecane (HBCD), α-hexachlorocyclohexane (α-HCH), chlorinated bornanes CHB-40 and CHB-62 revealed by the PLS model were not confirmed by partial correlations. TH levels in the present study appeared to be somewhat lower than levels measured in beluga whales from the Canadian Arctic. However, we were not able to determine if this was caused by different levels of OHCs, or differences in biological factors (e.g. age, sex, moulting status, and season) and analytical methods between the studies. Although the sample sizes were low and statistical models cannot depict the biological cause–effect relationships, this study suggests negative influences of specific OHCs, particularly PBDEs, on thyroid hormone levels in white whales. The impact this might have on individual and population health is unknown.
The Possible Effects of High Vessel Traffic on the Physiological Parameters of the Critically Endangered Yangtze Finless Porpoise (Neophocaena asiaeorientalis ssp. asiaeorientalis)
2018, Frontiers in Physiology
Quantitative Analysis of Thyroid Hormone Levels in the Caspian Seal Pusa caspica (Gmelin, 1788)
2018, Russian Journal of Marine Biology
Atlas of the Anatomy of Dolphins and Whales
2018, Atlas of the Anatomy of Dolphins and Whales

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Thyroid Function in Dolphins: Radioimmunoassay Measurement of Thyroid Hormones

SUMMARY

Lancet

Journal of Clinical Endocrinology and Metabolism

British Medical Journal

Archives of Pathology

Growth

The Investigation of Thyroid Disease

Aquatic Mammals