Thanks so much Diene! God, I had a complete brain freeze moment there... saying oestrogen dominance causes low thyroid and then asking why my T4 might be low..! Dumbo Yogabare.
Found an article by Peat and it says that "Estrogen inhibits the secretion of hormone by the thyroid gland itself, probably by inhibiting the proteolytic enzyme which dissolves the colloid." Wow. I'm text book Estrogen Dominance! Sounds weird, but it's such a relief to that all these pieces fit together.
Progesterone promotes the release of the hormones from the gland, so if your oestrogen is high, and prog is low, you won't produce T4. At the same time, the thyroid is essential for producing progesterone, and thyroid function also stimulates the liver to inactivate oestrogen's, so oestrogen dominance causes a viscous cycle of low prog and high oestrogen.
Now here's the interesting part:
So according to Peat, there are advantages to treating Ost dom with thyroid medication instead of progesterone, even though this is not how it's normally treated. I imagine it would be T4 that should be supplements, not cytomel? I'll have to check that...
"Progesterone (even one dose, in some cases) can break the cycle. However, if the gland is very big, the person can experience a few months of hyperthyroidism, as the gland returns to normal. It is better to allow the enlarged gland to shrink more slowly by using a thyroid supplement
If the problem is that the ratio of estrogen to progesterone is too high, though progesterone might itself be at a reasonable level, thyroid becomes crucial, to bring the estrogen level down to normal."
I've just posted about it on the Ray Peat forum, hopefully someone there will know more.
In the interim, Peat recommends this book on the thyroid: I think it's out of print now, but apparently you can still get copies and it's amazing:
Thomas Hodge McGavack (Author), James M. Winfield (Contributor), Walter L. Mersheimer (Contributor)
Apparently reprinted as paperback in 2010.
Thomas H. McGavack's 1951 book, The Thyroid, was representative of the earlier approach to the study of thyroid physiology. Familiarity with the different effects of abnormal thyroid function under different conditions, at different ages, and the effects of gender, were standard parts of medical education that had disappeared by the end of the century. Arthritis, irregularities of growth, wasting, obesity, a variety of abnormalities of the hair and skin, carotenemia, amenorrhea, tendency to miscarry, infertility in males and females, insomnia or somnolence, emphysema, various heart diseases, psychosis, dementia, poor memory, anxiety, cold extremities, anemia, and many other problems were known reasons to suspect hypothyroidism. If the physician didn't have a device for measuring oxygen consumption, estimated calorie intake could provide supporting evidence. The Achilles' tendon reflex was another simple objective measurement with a very strong correlation to the basal metabolic rate. Skin electrical resistance, or whole body impedance wasn't widely accepted, though it had considerable scientific validity.
"I think the basic anti-aging diet is also the best diet for prevention and treatment of diabetes, scleroderma, and the various "connective tissue diseases." This would emphasize high protein, low unsaturated fats, low iron, and high antioxidant consumption, with a moderate or low starch consumption.
In practice, this means that a major part of the diet should be milk, cheese, eggs, shellfish, fruits and coconut oil, with vitamin E and salt as the safest supplements."
- Ray Peat