The thyroid gland part 4, subclinical hypothyroidism explained


Are you tired all the time, gaining weight while eating the same amount of food? Is your skin dry and your hair falling out too? It can be easy to dismiss these symptoms as being down to living through a typical UK winter when many folks feel under par, suffer the effects of central heating and load up on carbs.

While much of our wellbeing can be age, gender or stress-related. If you are also increasingly sensitive to cold and feeling weak, and simply want to hibernate, your symptoms may suggest that your thyroid gland is not working optimally

Subclinical Hypothyroidism is a medical state in which one hormone made and stored in the thyroid gland is out of balance. In these cases, the level of thyroid-stimulating hormone (TSH) which comes from the pituitary gland is a little elevated. While the other hormones produced and stored by the thyroid gland, T3 and T4 (aka thyroxine), are within normal ranges.

Although around 1 in 3 patients with subclinical, Hypothyroidism will be symptomless. Those who do present to their doctor may have the same cascade of concerns as people presenting with full-blown Hypothyroidism, including:

  • Fatigue
  • Dry skin and dry, thinning hair
  • Increased sensitivity to cold
  • Memory problems
  • Constipation
  • Depression
  • Weight gain
  • Weakness
  • Pale, puffy face
  • Heavy and irregular menstruation
  • An enlarged thyroid, or Goiter

However, its tad confusing as research shows that around 20% of adults with normal thyroid hormone tests report one or more of these symptoms, and many associated with other conditions. Subclinical Hypothyroidism affects up to 20% of the adult population; it is more common in people of caucasian ethnicity, women, and older people too. Of those affected between 2- 5% will progress to full-blown Hypothyroidism each year, the risk factors and causes are the same as the full-blown condition, including:

  • A family history of Hashimoto’s disease.
  • Injury or trauma to the thyroid gland.
  • Following radioactive iodine therapy.
  • Taking medications that contain lithium or iodine.

Getting a diagnosis and treatment

Doctors diagnose subclinical Hypothyroidism with a blood test. There is a lot of debate about how and if subclinical Hypothyroidism should be treated, and the conflicting studies don’t make things any clearer.

The British Medical Journal (BMJ) published a systematic review in 2019, which looked at 21 trials with over 2000 participants. They concluded that with the burden of lifelong management and uncertainty on potential harmful side effects, almost all adults with subclinical Hypothyroidism do not benefit from treatment with thyroid hormones. Their essential advice to doctors included:

  • That they should not prescribe thyroid hormones to adults with subclinical Hypothyroidism because they do not lead to significant quality of life benefits or help the thyroid-related symptoms, including depressive symptoms and fatigue. 
  • Taking medication and attending repetitive testing on an ongoing or lifelong basis is difficult, and patient compliance is perennial an issue.
  • They concluded by advising that the emphasis for clinicians should be on monitoring those who are symptomatic, or at high risk for full-blown thyroid disease. This includes women planning a pregnancy or pregnant. Other risk groups include women who experience premature ovarian failure ad early menopause and those over 60 years, or with a family history of autoimmune illnesses, including Type I diabetes.

If this affects you, the best way forward is to talk with your doctor about your symptoms, blood tests, results, and any past medical history. If offered, treatment is usually with a synthetic thyroid hormone called Levothyroxine which is generally well-tolerated, but it may be several weeks before symptoms start to improve and the dosage may need adjusting to get the correct level for you.


The connection between Subclinical Hypothyroidism and cardiovascular disease is an ongoing debate. Some studies suggest that elevated thyroid-stimulating hormone levels when left untreated, may contribute to developing: high blood pressure, raised cholesterol and congestive heart failure, but more research is needed.

Self-help for subclinical Hypothyroidism

It’s essential to get an optimal amount of iodine in your diet along with:

  • Vitamin B-12 is necessary for cellular response and boosting energy production in cells. 
  • Selenium, which supports efficient thyroid synthesis and metabolism.
  • Zinc is also beneficial in improving thyroid function and hormone levels. 

However, there is little good scientific evidence that avoiding certain foods or changing your diet will help subclinical Hypothyroidism or avoid progression into the full condition. The best thing you can do for your thyroid function and general health is to eat a balanced diet of fresh food. If you plan to use supplements please check with your doctor and seek professional advice, to avoid potential interactions.


Díez JJ, et al. (2004). Spontaneous subclinical hypothyroidism in patients older than 55 years: An analysis of natural course and risk factors for the development of overt thyroid failure. DOI:10.1210/jc.2003-032061

Fatourechi V. (2009) Subclinical hypothyroidism: An update for primary care physicians. PMC2664572/

Vaz CK. (n.d.). Diagnosis and treatment of subclinical hypothyroidism. (n.d.). / about/ about-graves-disease/ patient-bulletins/ diagnosis-and-treatment-of-subclinical-hypothyroidism


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