Having an understanding of the endocrine system helps to see the big picture and how your changing hormones create a cause and effect loop.
The hypothalamus gland in the brain sends a message to the pituitary and ovaries that the child bearing years are coming to an end and, despite seemingly normal cycles, ovulation doesn’t always occur. Known as unnovulatory cycles, this causes a drop in progesterone since this vital hormone is only produced during ovulation and pregnancy. A drop in progesterone disrupts the fine balance between estrogen and progesterone that your body has relied on since adolescence. Estrogens become “unopposed” and the dominant hormone. This is common referred to as “estrogen dominance.”
The hypothalamus influences food intake, weight regulation, fluid intake and balance, thirst, body heat, and the sleep cycle. Pituitary hormones stimulate growth, egg development and release of hormones by other glands. The pineal gland plays a role in sexual maturation and the circadian rhythm.
Thyroid hormones regulate the metabolic rate of tissues, stimulate the contraction of heart muscle, and are necessary for normal growth and brain development. Parathyroid hormone regulates calcium, phosphorus, and magnesium levels. The adrenal glands regulate salt and water retention, some reactions of the immune system and blood pressure. The islets of Langerhans regulate blood sugar levels. The ovaries produce hormones that regulate the reproductive system.
As you can see, the entire endocrine system is impacted by your changing hormones. In perimenopause, the thyroid and adrenal glands are the two key glands that react the most. This is why many of the common symptoms of “the change” can not only mimic but also lead to hormone related health conditions like hypothyroidism, type II diabetes, adrenal insufficiency, osteoporosis, heart conditions, etc.