THE ADRENAL GLAND IMPACT
Not only does birth control suppress the production of testosterone from the adrenal gland but with various receptors located throughout the gland, it impacts other hormones secreted by the adrenal gland such as cortisol and aldosterone. Hormonal contraceptives, mainly by way of the synthetic estrogen, increase aldosterone levels [5]. Aldosterone is a hormone that stimulates the kidneys to restrict passage of sodium from being excreted through the urine; therefore more is reabsorbed into the bloodstream for usage while simultaneously more potassium is excreted through the urine. This causes a higher level of sodium in the body in relation to the amount of potassium. This can lead to weight gain, edema (swelling), high blood pressure and a strong influence on metabolic health (more on why this is so important here: Minerals + Metabolism) [5]. Additionally, birth control usage has been shown to significantly blunt the production of cortisol in response to stress [2,6]. If you’ve been on a health journey for some time you’re probably thinking wait, this a good thing, right? Everyone is always discussing lowering stress and the hormone, cortisol. But the reality is we still need cortisol and we need a healthy amount of stress for our body to function how it was made to function. The adrenal gland and cortisol are key players in your hypothalamic-pituitary-adrenal axis. Low cortisol production sends feedback to these other areas in the brain that also influence your mental health and thyroid health signaling more or less production of hormones but inevitably throwing off homeostasis [6]. Not having sufficient cortisol also does not mean your body will not experience stress. You will still experience the sympathetic response to stress or exciting circumstances (increased heart rate, slowed digestion, sweat, etc) but without the cortisol production many women report feeling almost apathetic to stimulating situations when taking hormonal contraceptives [2,3,6]. Upon discontinuation of birth control, your body should eventually pick up cortisol production again but the impacts low cortisol had on your mental health and thyroid will be much longer lasting.
THE THYROID IMPACT
As with the Sex-Hormone Binding Globulin (SHBG), another protein made in the same area of the liver and influenced by hormones, mainly estrogen, is known as the Thyroid Binding Globulin (TBG) [7]. Similarly to SHBG, TBG binds to circulating thyroid hormones (or thyroxine, more commonly known as T3 and T4) to transport them throughout the body to the appropriate tissues for utilization [7,8]. Hormonal contraceptives have been shown to increase the amount of TBG therefore decreasing the amount of available, free, unbound T3 and T4. The concentrations of the amount of free thyroid hormones in the body are the triggers which send a message to the pituitary gland to say: “we need more or less thyroid hormone”. When the free, unbound amount of thyroid hormone levels are low this causes the brain to increase the levels of TSH (thyroid stimulating hormone) to tell the thyroid gland to make more hormones to maintain circulating, free levels [7]. This rise in TSH can cause misleading interpretations on thyroid health often misconstrued as the thyroid not producing enough when in fact there may be enough thyroid hormones present, they are simply unusable and bound to more proteins produced by higher, synthetic estrogen [7]. Alternatively, women with subclinical hypothyroidism or thyroid complications prior to starting hormonal contraceptives may have exacerbated symptoms while on birth control and long after discontinuation as the thyroid gland attempts to re-regulate itself [7,8].
References
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