Undiagnosed and untreated thyroid disease can be a cause for infertility or even of recurrent miscarriage. The thyroid hormone is crucial for growth and metabolism; since it regulates cellular function, any abnormality in it can also impact your fertility. These are the different types of thyroid disorders:

  • Hypothyroidism- This is an underactive thyroid and is a common cause of infertility. If the thyroid is underactive, the hypothalamus as well as the pituitary gland can sense this. They attempt to get things back to normal by increasing levels of TRH (thyroid-releasing hormone) and TSH (thyroid-stimulating hormone) in your body.

The TRH that’s produced by the hypothalamus prompts the pituitary to then release TSH; in turn, this stimulates the thyroid to do its job. However, TRH also prompts the pituitary to release more of the hormone prolactin. Higher prolactin levels can impact ovulation as it suppresses the release of the FSH and LH hormones (both of which stimulate the ovary). Low thyroid hormone levels may interfere with the speed at which body metabolizes sex hormones; this can cause ovulatory disorders.

  • Excess thyroid hormone – This could be a result of an overactive thyroid gland. Sometimes, it could be a result of excessive thyroid hormone and this too can cause problems. Thyroid hormone can block the effect of estrogen at different points in the body. It means the estrogen won’t be as effective at doing its job. This makes the uterine lining (endometrium) unstable and it can also cause abnormal uterine bleeding.

The most sensitive way to predict thyroid abnormality is to get a simple thyroid-stimulating hormone (TSH) test done. If this is abnormal, you will be required to do a complete thyroid panel to test your T3, T4 and TSH levels.

A normal TSH level is in the 0.5 to 5.5 mIU/ml range. If it’s over 5.5, it’s considered hypothyroid, or underactive; in case it’s under 0.5 it’s considered hyperthyroid, or overactive.

Note: That there is an ongoing controversy amongst endocrinologists, and an increasing number of experts are of the opinion that the normal range should be revised, to 0.3- 3.0. In case you don’t have any symptoms but still have a high TSH, you have subclinical hypothyroidism.

Some infertility specialists are of the opinion that for optimal fertility, the TSH level should be 2 mIU/ml or less. Though it’s still controversial, they treat patients with thyroxine to get it to that level.

If it is found that you have hypothyroidism, Eltroxine (thyroid hormone replacement) is extremely effective to restore fertility. It might take 1-2 months for the medication to take effect and to get your thyroid levels back to normal. Once you have started the medication, it’s important that you check your TSH levels to ascertain that they are in the normal range. Typically, you will have to continue the medicines for all your life. The thyroid function check will have to be auctioned every 6 months.

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Authored by : Dr Aniruddha Malpani, MD and reviewed by Dr Anjali Malpani.

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