What is Hypothyroidism
What is Hypothyroidism?

Hypothyroidism is a disease that occurs when the thyroid is underactive.1

Because the thyroid affects every organ, tissue and cell in the body,2 an underactive thyroid leads to various body functions slowing down.3

Thyroid Gland Thyroid and Pregnancy
How It Develops

How It Develops?

Hypothyroidism develops slowly over months or years. Although fatigue and weight gain are common symptoms of hypothyroidism, they can also have other causes.4

What are the Causes of Hypothyroidism?

There are many causes of hypothyroidism.

Hashimoto's Thyroiditis

Most cases of hypothyroidism are caused by Hashimoto’s thyroiditis. This is an autoimmune disease that causes your immune system to damage or destroy the thyroid gland.5

Thyroid Surgery

Hypothyroidism can also result from radioactive iodine or thyroid surgery where part or all of the thyroid gland is removed. Both are used to treat hyperthyroidism (overactive thyroid) or thyroid cancer.4

Postpartum Thyroiditis

Sometimes after childbirth, women can develop a condition called postpartum thyroiditis (PPT), which is also thought to be an autoimmune disease.6 PPT may cause hypothyroidism due to depleted thyroid hormone stores.7 Treatment is based on severity of symptoms.7 In PPT, levothyroxine 4 (LT4) should be considered for minor symptoms and if the patient wants to get pregnant again.6

Iodine Deficiency

One of the less common causes of hypothyroidism is iodine deficiency, although this is very rare in developed countries where salt is iodized. This is because iodine is a key component of thyroid hormones – if you don’t have enough iodine, your thyroid cannot make enough thyroid hormone.8

Hypothyroidism Symptoms

There are many hypothyroidism symptoms, some of which include:

Hypothyroidism can lead to serious consequences if left untreated.4 If you are concerned about your thyroid, take note of the thyroid symptoms you are experiencing and discuss them with your doctor.

Fatigue9 Fatigue Depression9 Depression Weight Gain9 Weight Gain Cold Intolerance9 Cold Intolerance Dry Skin and Hair9 Dry Skin and Hair Sleep Apnea10 Sleep Apnea Infertility3 Infertility Constipation9 Constipation Coarse Hair and Hair Loss9 Coarse Hair and Hair Loss Muscle Pain9 Muscle Pain Brittle Nails11 Brittle Nails Hoarse Voice9 Hoarse Voice Heavy Periods9 Heavy Periods Swollen Face9 Swollen Face Difficulty Concentrating12 Difficulty Concentrating Erectile Dysfunction13 Erectile Dysfunction
Subclinical hypothyroidism

Subclinical Hypothyroidism

Subclinical hypothyroidism is a condition where the thyroid has slight disturbance of the function.14 In subclinical hypothyroidism, blood tests will show a mildly elevated TSH level, with normal levels of the thyroid hormone T4.15

Subclinical hypothyroidism may eventually progress to “overt” or complete hypothyroidism.14 Patients with antibodies targeting their thyroid are at higher risk of progressing to overt hypothyroidism.16 It is important to note that patients with subclinical hypothyroidism may or may not have symptoms.15

Subclinical hypothyroidism is common in women and in older people.15 Studies show that it affects 15% of women over 60 years of age17 and 4–20% of adults.15

Where Can I Find Hypothyroidism Treatment or Thyroid Medication?

Not all cases of subclinical hypothyroidism require hypothyroidism treatment. Your doctor can determine if treatment is required or if you need thyroid medication. If you think you are experiencing any symptoms of hypothyroidism, speak to your doctor.

References:

1. Beers MH, Fletcher AJ, Jones TV, Porter R, Berkwits M, Kaplan JL, eds. The Merck Manual of Medical Information. 2nd ed. Merck Research Laboratories; 2003. 2. Khan YS, Farhana A. Histology, thyroid gland. In: StatPearls. National Library of Medicine; 2023. 3. Hypothyroidism. MedlinePlus. Accessed May 10, 2023. https://medlineplus.gov/hypothyroidism.html 4. Hypothyroidism (underactive thyroid). National Institute of Diabetes and Digestive and Kidney Diseases. Accessed May 16, 2023. https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism 5. Hashimoto’s disease. National Institute of Diabetes and Digestive and Kidney Diseases. Accessed May 16, 2023. https://www.niddk.nih.gov/health-information/endocrine-diseases/hashimotos-disease 6. Rad NS, Deluxe L. Postpartum thyroiditis. In: StatPearls. National Library of Medicine; 2023. 7. Postpartum thyroiditis. Johns Hopkins Medicine. Accessed May 16, 2023. https://www.hopkinsmedicine.org/health/conditions-and-diseases/postpartum-thyroiditis 8. Hypothyroidism: should I take iodine supplements? Mayo Clinic. Accessed May 16, 2023. https://www.mayoclinic.org/diseases-conditions/hypothyroidism/expert-answers/hypothyroidism-iodine/faq-20057929 9. Hypothyroidism (underactive thyroid). Mayo Clinic. Accessed May 18, 2023. https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284 10. Mete T, Yalcin Y, Berker D, et al. Relationship between obstructive sleep apnea syndrome and thyroid diseases. Endocrine. 2013;44(3):723-728. 11. Safer JD. Thyroid hormone action on skin. Dermatoendocrinol. 2011;3(3):211-215. 12. Psychological symptoms and thyroid disorders. British Thyroid Foundation. Accessed May 19, 2023. https://www.btf-thyroid.org/psychological-symptoms-and-thyroid-disorders 13. Gabrielson AT, Sartor RA, Hellstrom WJG. The impact of thyroid disease on sexual dysfunction in men and women. Sex Med Rev. 2019;7(1):57-70. 14. Cojić M, Cvejanov-Kezunović L. Subclinical hypothyroidism: whether and when to start treatment? Open Access Maced J Med Sci. 2017;5(7):1042-1046. 15. Bekkering GE, Agoritsas T, Lytvyn L, et al. Thyroid hormones treatment for subclinical hypothyroidism: a clinical practice guideline. BMJ. 2019;365:I2006. 16. Collet TH, Bauer DC, Cappola AR, et al. Thyroid antibody status, subclinical hypothyroidism, and the risk of coronary heart disease: an individual participant data analysis. J Clin Endocrinol Metab. 2014;99(9):3353-3362. 17. Al Eidan E, Ur Rahman S, Al Qahtani S, Al Farhan Al, Abdulmajeed I. Prevalence of subclinical hypothyroidism in adults visiting primary health-care setting in Riyadh. J Community Hosp Intern Med Perspect. 2018;8(1):11-15.