Hypothyroidism, which is a type of thyroid disease, is very common in women. Hypothyroidism is a common condition in which the thyroid does not make or release enough thyroid hormone into the bloodstream.

Hypothyroidism is more common in women who were born small and had a low body mass index as kids. It is also a common problem, especially for women over 60. Hypothyroidism is usually more likely to happen to women after menopause.

The most common cause of primary hypothyroidism is a lack of iodine, especially in places around the world where iodine is scarce. Drugs like amiodarone, thalidomide, oral tyrosine kinase inhibitors (sunitinib, imatinib), stavudine, interferon, bexarotene, perchlorate, rifampin, ethionamide, phenobarbital, phenytoin, carbamazepine, interleukin-2, and lithium are also common causes of hypothyroidism. Other reasons include radioactive iodine therapy for the thyroid, thyroid operation, and head or neck radiation therapy

Most of the time, the signs of hypothyroidism come on slowly, sometimes over the course of years. Some of the symptoms include: 

• Feeling tired (fatigue).
• Having tingling and numbness in your hands.
• Gaining weight.
• Having skin and hair that are dry and rough.
• Experiencing a decreased sexual interest.
• Having periods that are heavy and come often.
• Drooping eyelids, as well as puffiness in the eyes and face
• Becoming more forgetful.

Doctors will order a test that measures free T4, such as a free T4 (FT4) or free T4 index (FTI). Most of the thyroid hormone in the blood is in the form of T4.

If your TSH is high and your FT4 or FTI is low, it means you have primary hypothyroidism from a disease in your thyroid gland. If you have a low TSH and a low FT4 or FTI, hypothyroidism is caused by a problem with the pituitary gland.

Treatment

Levothyroxine is the standard treatment for hypothyroidism. The standard daily dose of levothyroxine replacement is 1.6 mcg/kg. To help the body absorb it, levothyroxine should be taken 30–45 minutes before breakfast and at least 3 hours after a meal at bedtime, which are the best times for most patients. 

Also, elemental supplements like calcium and magnesium, to name a few, do change how well levothyroxine is absorbed. Proton pump inhibitors and other commonly used drugs also make it harder for the body to absorb levothyroxine. It is very important to keep the same brand or type of levothyroxine. When switching between generic formulations, certain individuals with hypothyroidism may experience adverse effects due to subtle but significant differences in their dosage.

Hypothyroidism is not preventable. Monitoring for hypothyroidism symptoms is the best method to avoid the development of a more severe form of the ailment or the disruption of your daily life caused by the symptoms. Some studies also suggest that eating foods high in iodine can help prevent thyroid diseases, but the results of these studies vary.

References

Patil N, Rehman A, Jialal I. Hypothyroidism. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519536/

Wartofsky, L., Van Nostrand, D., & Burman, K. D. (2006). Overt and ‘subclinical’ hypothyroidism in women. Obstetrical & gynecological survey, 61(8), 535–542. https://doi.org/10.1097/01.ogx.0000228778.95752.66

Cleveland Clinic (2022). Hypothyroidism. Retrieved November 22, 2022, from https://my.clevelandclinic.org/health/diseases/12120-hypothyroidism

American Thyroid Association (2022). Thyroid Function Tests. Retrieved November 22, 2022, from https://www.thyroid.org/thyroid-function-tests/