All of your hormones and hormonal glands have an intricate relationship with each other, giving each other feedback and having an influence on each others levels. A little bit of a one hormone going up can cause another to go down, and so imbalances can have a flow on effect which can cause many symptoms.
A major connection to consider is the link between your thyroid health and your oestrogen and progesterone levels.
We know excessive levels of oestrogen can have an impact on thyroid health, with too much oestrogen making your thyroid balance go out of whack, but how does it actually do this?
Oestrogen can raise thyroid binding globulin, which will lower free thyroid hormone levels.
This can be a problem for women who are on artificial hormones such as the oral contraceptive pill, or for women who have higher than normal levels of oestrogen in their system.
Typically this will show up as heavy periods and longer menstrual cycles. The increased oestrogen results in a relative deficiency of progesterone which is responsible for the thinning of the endomentrial lining. It can also impact on the coagulatory factors in the blood which control excessive bleeding.
Potenially thyroid problems can also contribute towards amenorrhoea, when your period disappears for a while.
Thyroid issues can also cause oestrogen to be bound up and carried away less than it should be, as thyroid problems can indirectly cause a reduced level of Sex Hormone Binding Globulin (SHBG) which would typically bind to excess levels of hormones such as oestrogen.
Oestrogen imbalance can be the missing piece of the puzzle for many women (and men) who have issues with T3 balance. It is a cycle that feeds itself until the original cause of the thyroid imbalance or oestrogen excess is addressed.
High Oestrogen -> Increased thyroid binding globulin -> low free thyroid hormone levels.
Low Thyroid Function -> Low SHBG -> High Oestrogen
An interesting action of oestrogen is that it can increase the proliferation of thyroid cells. This isn’t always a bad thing, as it can be helpful to regulate thyroid function and help the repair of the thyroid gland when oestrogen is in normal ranges. However in excess this could result in an increased risk of autoimmune thyroid disease or thyroid cancer.
Now we know that oestrogen isn’t the only female hormone. Progesterone is another important hormone for women, and it too has a connection with the thyroid hormones.
The thyroid – progesterone connection goes two ways. Thyroid helps stimulate release of progesterone from the luteal cells. Given this, we can consider that for some women who appear to have progesterone deficiency they may have underlying issues with their T3 hormone as the cause.
And progesterone deficiency can impact on the conversion of T4 to T3 via reduced deiodinase 2 activity. So for women who are post-menopausal, who have had an oophorectomy (ovaries removed surgically) or do not ovulate regularly (e.g in Hypothalamic Amenorrhoea or PCOS) the state of their thyroid is something to consider.
Imbalances in both progesterone and oestrogen can impact your immune system balance which can increase your risk of autoimmune disease, an issue which is common for thyroid problems.
If you suspect that you have an issue with your hormones and would like some holistic support or perhaps you would like to discuss testing options, contact your health care practitioner to discuss your options.
Role of estrogen in thyroid function and growth regulation. https://doi.org/10.4061/2011/875125
Clinical review: Thyroid dysfunction and effects on coagulation and fibrinolysis: a systematic review. https://doi.org/10.1210/jc.2007-0199
An evidence for the transcriptional regulation of iodothyronine deiodinase 2 by progesterone in ovarectomized rats. https://doi.org/10.1007/s13105-013-0307-y
Menorrhagia and hypothyroidism. Evidence supports association between hypothyroidism and menorrhagia. https://doi.org/10.1136/bmj.https://doi.org/10.1136/bmj.320.7235.649
Menstrual disturbances in various thyroid diseases. https://doi.org/10.1507/endocrj.k10e-216
Thyroid disease and female reproduction. https://doi.org/10.1111/j.1365-2265.2007.02752.x