Why Measure Thyroid Stimulating Hormone (TSH)

The thyroid is a butterfly-shaped endocrine organ at the base of the neck that helps regulate metabolism. Thyroid disease is a common ailment affecting over 6% of reproductive age women. Thyroid disease is 5 to 8 times more common in women than in men. The easiest way of determining thyroid function is by measuring Thyroid Stimulating Hormone (TSH) in the blood. TSH is produced in the Pituitary Gland at the base of the brain and stimulates the thyroid to produce and secrete thyroid hormones. Many patients ask us why measure Thyroid Stimulating Hormone (TSH)?

Hypothyroidism is a medical condition caused by an underactive thyroid gland that does not adequately respond to TSH stimulation. Consequently in hypothyroidism the TSH is elevated. An elevated TSH can also increase Prolactin production by the Pituitary which can further compromise reproduction.  In hyperthyroidism the thyroid is over active and the TSH level is low. The “normal” reference range in most clinical laboratories for TSH is 0.4 to 4.5mIU/L. Most Endocrinologists, especially Reproductive Endocrinologists consider a TSH above 2.5mIU/L as abnormal.

During pregnancy maternal thyroid production increases by at lest 20% and often by as much as 40%. Normal thyroid function before and during pregnancy can reduce the risk of implantation failure, miscarriage, preterm labor, neonatal and early childhood development problems.

Measuring TSH should be part of the initial evaluation of infertility and recurrent pregnancy loss. Keeping the range of TSH between 0.1 and 2.5mIU/L may enhance fertility and reduce the obstetrical, neonatal and early childhood development risks associated with an elevated TSH.

If you have more questions, please contact us.