With postpartum thyroiditis, postpartum means "after birth", thyroid refers to the thyroid gland, and -itis means inflammation, so postpartum thyroiditis is an inflammation of the thyroid gland that women experience after giving birth.
Normally, the hypothalamus, which is located at the base of the brain, secretes thyrotropin-releasing hormone, or ΤRH, into the hypophyseal portal system - which is a network of capillaries linking the hypothalamus to the anterior pituitary gland.
The anterior pituitary then releases a hormone of its own, called thyroid-stimulating hormone, thyrotropin, or simply TSH.
TSH stimulates the thyroid gland, which is a gland located in the neck that looks like two thumbs hooked together in the shape of a “V”.
If we zoom into the thyroid gland, we’ll find thousands of follicles, which contain a sticky substance called colloid, which sits within follicular cells.
Follicular cells convert the protein thyroglobulin into two iodine-containing hormones, triiodothyronine or T3, and thyroxine or T4.
Once released from the thyroid gland, these hormones enter the blood and the majority is bound to circulating plasma proteins, with only a small amount of T3 and T4 traveling unbound in the blood.
Ultimately, these two hormones get picked up by nearly every cell in the body.
Once inside the cell T4 is mostly converted into T3, and it can exert its effect. T3 speeds up the basal metabolic rate.
So as an example, they might produce more proteins and burn up more energy in the form of sugars and fats. It’s as if the cells are in a bit of frenzy.
T3 increases cardiac output, stimulates bone resorption - thinning out the bones, and activates the sympathetic nervous system, the part of the nervous system responsible for our ‘fight-or-flight’ response.