This study certainly seems to throw up a number of questions - but few or no answers. Fascinating and I sincerely hope that the full paper eventually becomes accessible on-line.
Endocrinology. 2013 Oct 3. [Epub ahead of print]
Thyroid autoantibodies are rare in non-human great apes and hypothyroidism cannot be attributed to thyroid autoimmunity.
Aliesky H, Courtney CL, Rapoport B, McLachlan SM.
Source
Thyroid Autoimmune Disease Unit, Cedars-Sinai Research Institute and UCLA School of Medicine, Los Angeles, CA.
Abstract
The great apes include, in addition to Homo, the genera Pongo (orangutans), Gorilla (gorillas), and Pan, the latter comprising two species, P.troglodytes (chimpanzees) and P.paniscus (bonobos). Adult-onset hypothyroidism was previously reported in four individual non-human great apes. However, there is scarce information on normal serum thyroid hormone levels and virtually no data for thyroid autoantibodies in these animals. Therefore, we examined thyroid hormone levels and TSH in all non-human great ape genera including adults, adolescents and infants. Because hypothyroidism in humans is commonly the end-result of thyroid autoimmunity, we also tested healthy and hypothyroid non-human great apes for antibodies to thyroglobulin (Tg), thyroid peroxidase (TPO) and the thyrotropin-receptor (TSHR). We established a thyroid hormone and TSH database in orangutans, gorillas, chimpanzees and bonobos (447 individuals). The most striking differences are the greatly reduced free-T4 and free-T3 levels in orangutans and gorillas versus chimpanzees and bonobos, and conversely, elevated TSH levels in gorillas versus Pan species. Antibodies to Tg and TPO were only detected in 2.6% of adult animals versus ∼10% in humans. No animals with Tg, TPO or TSHR antibodies exhibited thyroid dysfunction. Conversely, hypothyroid non-human great apes lacked thyroid autoantibodies. Moreover, thyroid histology in necropsy tissues was similar in euthyroid and hypothyroid individuals and lymphocytic infiltration was absent in two hypothyroid animals. In conclusion, free-T4 and free T3 are lower in orangutans and gorillas versus chimpanzees and bonobos, the closest living human relatives. Moreover, thyroid autoantibodies are rare and hypothyroidism is unrelated to thyroid autoimmunity in non-human great apes.
Rod, as you observed, lots of questions but no answers. Humans have adapted to far greater climate variations which would lead me to believe that although there are undoubtedly similarities there are bound to be distinct differences also. PR
Rod, wonderful photography, nobody does it better consistently than Nat Geo, one of the truly good things in the US. Haven't noticed any reports of monkeys in the Artic or Antarctic though, or above the artic circle hanging out with the reindeer. I was watching 'Nature' last night and this series on birds around the world with some of the footage from cameras on the birds' backs. They had some shots of the cranes flying thru the Himalayas and the geese that fly over, not thru, the Himalayas, just breathtaking. PR
Very interesting Rod - thank you. Also great photos. I think the fact that some animals with the anti-bodies did not show to be Hypo is interesting. Wonder how old they were ? - as I believe it can take time for the illness to reveal itself or for symptoms to develop...just a thought.
My vet informs me that dogs can also suffer with AID of the thyroid - probably caused by modern feeding methods...who knows !
I have always felt there is a mismatch between autoimmunity, antibodies and actual thyroid deterioration. Although there is lots of evidence of association, and some evidence of mechanism, I feel short-changed by lack of a clear description of what happens, when and why.
Ta Rod, an interesting one, but a few definite thoughts:
I'm not sure how these guys can blithely purport to reliably detect hypothyroidism and thyroid auto immune issues in these animals - not given the poor correlation between thyroid test results and patient reality in hypothyroid humans.
Our symptoms and protestations of hypothyroidism are routinely ignored in favour of dubious test values ('your thyroid is normal') despite our speaking to doctors, so your average ape desn't seem likely to get far in this regard.
I'm another that's dubious about the comments on auto immune thyroid disease. There's a suggestion that the presence or not of antibodies was the marker used to detect hypothyroidism because 'hypothyroidism in humans is commonly the end result of auto immunity'.
End stage thyroid auto immune issues can eventually destroy the thyroid, but often not for many years - and that doesn't mean that auto immune issues are in the first instance the direct cause of hypothyrodism, or even necessarily present with the condition....
It's surely far more arguable that thyroid auto immune disease in humans is often a consequence of hypothyroidism and a related and interdependent complex of imbalances and functional problems caused by factors like stress, environmental and dietary peculiarities interacting with inherited tendencies. The ability of the standard tests to reliably detect thyroid auto immune issues seems anyway from experience to be suspect....
They then go on to say that hypothyroid apes lacked thyroid antibodies, and that antibodies in the apes were not linked with thyroid dysfunction. That fits with the above possibility (that thyroid disease isn't necessarily caused by auto immunity), but given their linking of hypothyroidism to auto immunity begs the question of how they determined the hypothyroidism in those cases.
It doesn't seem unreasonable that apes might see a much lower incidence of auto immune thryoid disease than humans - not given our unnatural modern diet, environment, and lifestyle and our (over?) active minds.
All in all it feels like somebody might have done well to have simply presented the factual data (the recorded blood hormone and antibody levels in the sample population) - and to have backed off on the theorising and drawing of conclusions that de-facto suggest that thyroid testing and hypothyroidism in humans is well understood territory/hard science....
There is, of course, kudos to have been the first to mention in print... well, anything!
Definitely the potential for interpretation. I do hope that it triggers a bit more research because it could very well help to identify differences which will help to unlock the mysteries.
It doesnt reveal anything about human thyroid disease.what i thought is interesting is that the gorillas and orangutans had lower levels of t3&t4;as arent they both vegetarian animals?
HI C. I saw that too. Another distinction between apes and monkeys might be that the former (that have the low thyroid hormone levels) are as well as vegetarian also far less energetic/more lethargic in their behaviour...
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