The main function of the thyroid gland is to make thyroxine (T4) and triiodothyronine (T3) hormones. These hormones are important for the growth and normal function of the body, as well as for breastfeeding.
Thyroid diseases include hypothyroidism (under-active thyroid), hyperthyroidism (over-active thyroid), and thyroid cancer. There is also a condition called post-partum thyroiditis which sometimes includes both a hyperthyroid phase and a hypothyroid phase.
Symptoms of hypothyroidism include:
Some breastfeeding mothers with hypothyroidism struggle to make a full milk supply. Thyroid hormones play a role in normal breast development and helping breasts to make milk. When not enough of the thyroid hormones are made, a mother’s milk supply may be affected.
Hypothyroidism is treated with thyroxine in order to bring the levels back to normal. Women who have been properly treated for hypothyroidism report they have had no problems with their milk supply.
Some women report that their milk supply is sensitive to the level of thyroid hormone in their bloodstream. That is, some women report that having their thyroid hormone levels within the normal range was not enough to support full milk production but they have a full milk supply when their thyroid hormone level is within the upper part of the normal range. This may reflect their own personal set point.
Symptoms of hyperthyroidism include:
Hyperthyroidism is usually treated with anti-thyroid drugs which reduce the amount of thyroid hormones being made. Radioactive iodine or surgery are other treatments for hyperthyroidism, particularly if it is long standing or difficult to control with medication.
Some women with hyperthyroidism report a large milk supply, but others seem to have difficulty with their letdown reflux.
We suggest to get regular testing done for T3, T4 & TSH hormones every quarter so that any irregularities can be handled timely. If thyroid hormones are in check, there should not be any issues with the supply.