The Thyroid

The thyroid gland is the “master controller” of metabolism.
Hypothyroidism

Hypothyroidism

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What is hypothyroidism?

Hypothyroidism, or an under active thyroid gland, is a common condition in which the thyroid gland does not produce enough thyroid hormones.1 This under-production of hormones slows down the body’s metabolism, often leaving patients feeling cold, tired and depressed.2 If you suffer from hypothyroidism then you are also likely to notice you have gained weight, despite following a sensible diet and exercising regularly.1

How common is it?

About 10% of thyroid patients in Singapore are affected by hypothyroidism. The most common causes are Hashimoto’s thyroiditis (a form of autoimmune thyroid disease) and previous treatment for hyperthyroidism (i.e., radioactive iodine or thyroid surgery). People of Indian ethnicity have a higher risk of developing this disorder due to Hashimoto’s thyroiditis than Chinese or Malays.3 

Symptoms of hypothyroidism

The symptoms of hypothyroidism are unpleasant and can affect a person’s self-esteem, work, and home and family life.4

Symptoms include:1,5,6

  • Fatigue/lethargy
  • Slow heart rate
  • Cold intolerance
  • Weight gain or difficulty losing weight
  • Depression
  • Constipation
  • Abnormal menstrual periods or fertility problems
  • Muscle aches or cramps
  • Thin and brittle hair and fingernails, and/or dry flaky skin
  • Decreased libido

If left untreated, hypothyroidism can cause more serious complications and even become life-threatening. Severe complications of hypothyroidism include:

  • Slipping into a coma1,5
  • Heart failure1
  • Therapy-resistant depression1
  • An increased risk of Alzheimer’s disease in women7

Who is at risk?

  • Women are generally more prone to developing hypothyroidism due to autoimmune thyroid disease
  • People who have received treatment for hyperthyroidism such as radioactive iodine or thyroid surgery
  • People who have relatives with autoimmune thyroid disease1,8
  • People with autoimmune diseases, such as type 1 diabetes or rheumatoid arthritis1
  • People who are taking lithium for bipolar disorder8
  • Patients who have undergone neck or upper chest radiation treatment 


How thyroid hormones impact your heart

The heart is a major target of thyroid hormones.

Too little thyroid hormone as a consequence of an underactive thyroid (hypothyroidism) may cause:10

  • Increased levels of low-density lipoprotein (“bad”) cholesterol, total cholesterol, and triglycerides
  • High blood pressure
  • Slow heart rate (less than 60 beats per minute)
  • Increased stiffness of the walls of blood vessels
  • Increased strain on the heart

Even mild hypothyroidism worsens heart disease

Mild hypothyroidism (also known as subclinical hypothyroidism) affects 4–20% of the population.11 It is more common in women than in men and occurs with increasing frequency with age.12 If you have both heart disease and a slightly underactive thyroid, then it is vital that your thyroid function is returned to normal. The presence of both diseases is associated with increased risk for death from heart disease.13

Diagnosing hypothyroidism

Many people remain undiagnosed with thyroid problems and suffer for a long time as their symptoms are often confused with those of other conditions, such as depression or weight gain.9 Hypothyroidism can be confirmed by your doctor through a simple blood test called the thyroid function test which checks the level of thyroid-stimulating hormone (TSH) and thyroid hormones in your blood.

If you are concerned that you could be suffering from problems with your thyroid gland, please discuss this with your doctor. To aid your consultation, download our Wellbeing Diary to help you keep a check of the symptoms you are experiencing, or try our short thyroid disorders symptom checker.

How is hypothyroidism treated?

Treatment for hypothyroidism is straightforward, well-established, and highly effective. As there is no cure for hypothyroidism, the aim of treatment is to replace the missing thyroid hormones in the body.2 Appropriate medication, taken daily, should enable most patients to live a symptom-free life.9

If you have been diagnosed with hypothyroidism, it is important to remember that treatment is a lifelong commitment and medication has to be taken every day in the correct dose and timing as prescribed by your doctor for optimal benefit. This may seem a bit daunting, but by taking control of your condition and following your treatment plan, you should be able to stay healthy and remain symptom-free. It is advisable to see your doctor more frequently if any changes in your condition occur.2

Summary

  • Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones
  • The most accurate way of diagnosing hypothyroidism is through a blood test known as thyroid function test
  • Treatment of hypothyroidism is to replace the missing thyroid hormones in the body via oral medication, which is effective
    and straightforward

References

  1. Hypothyroidism: too little thyroid hormone. Available at: https://www.endocrineweb.com/conditions/thyroid/hypothyroidism-too-little-thyroid-hormone. Last accessed February 2022.
  2. American Thyroid Association. Hypothyroidism. Available at: http://www.thyroid.org/wp-content/uploads/patients/brochures/Hypo_brochure.pdf. Last accessed February 2022.
  3. Aw TC, et al. Thyroid function tests. Proc Singapore Healthc. 2011; 20: 132-7.
  4. British Thyroid Foundation. Your guide to psychological symptoms and thyroid disorders. Available at: https://www.btf-thyroid.org/psychological-symptoms-and-thyroid-disorders. Last accessed February 2022.
  5. Yeo JLS, Yong NTWM, Mahendran DCJ, et al. Approach to goitre in family medicine. Singapore Med J.2022; 63: 604‒614.
  6. Poppe K, Velkeniers B, Glinoer D. The role of thyroid autoimmunity in fertility and pregnancy. NatClin Pract Endocrinol Metab 2008; 4: 394-405.
  7. Tan ZS, Beiser A, Vasan RS et al. Thyroid function and the risk of Alzheimer disease: the Framingham Study. Arch Intern Med 2008; 168: 1514-1520.
  8. Very well Health. Causes and symptoms of hypothyroidism. Available at: https://www.verywellhealth.com/hypothyroidism-causes-risk-factors-3231721. Last accessed May 2023.
  9. Razvi S, Mrabeti S, Luster M. Managing symptoms in hypothyroid patients on adequate levothyroxine: a narrative review.  Endocrine Connect. 2020; 9: R241-R250.
  10. Hormone Health Network. Hypothyroidism and heart disease. Available at: https://www.hormone.org/diseases-and-conditions/hypothyroidism. Last accessed February 2022.
  11. Razvi S, Weaver JU, Pearce SH. Subclinical thyroid disorders: significance and clinical impact. JClin Pathol. 2010; 63: 379-86.
  12. Kek PC, Ho SC, Khoo DH.Subclinical thyroid disease. Singapore Med J. 2003; 44: 595-600.
  13. Iervasi G, Molinaro S, Landi P et al. Association between increased mortality and mild thyroid dysfunction in cardiac patients. Arch Intern Med 2007; 167: 1526–1532.
SG-NONT-00025 | December 2023