Does Borderline Hypothyroidism Require Treatment?

Do subclinical and borderline hypothyroidism require treatment?Subclinical hypothyroidism, also called mild thyroid failure or borderline hypothyroidism is diagnosed when thyroid hormone levels are within normal reference range but TSH is mildly elevated.

While this condition affects between 4% and 10% of the population it is more common in women than men and its prevalence increases with age. Between 7% and 26% of the elderly have borderline hypothyroidism.

Studies show that thyroid antibodies can be detected in 80% of patients with borderline hypothyroidism and autoimmune thyroid disease or Hashimoto’s is the most common cause of elevated TSH. The majority of patients with subclinical hypothyroidism have elevated TSH that is lower than 10 mIU/L.

Other causes of borderline hypothyroidism include a mild thyroid failure due to thyroid surgery, previous radioiodine therapy and external radiation therapy as well as temporary subclinical hypothyroidism after episodes of postpartum, silent and subacute thyroiditis.

Some people with borderline hypothyroidism don’t have symptoms but many do. Subclinical hypothyroidism has a  very wide range of symptoms because the thyroid gland affects the function of all cell in your body. Thyroid hormones determine our metabolism.

When metabolism slows down you may start to experience fatigie even when getting an adequate amount of sleep, gain weight or have difficulty to lose weight, depression, brain fog, memory issues, cold intolerance, cold hands and feet or wearing warm clothes and still freezing when other people feel comfortable with the room temperature.

Some other typical symptoms of borderline hypothyroidism are constipation, hair loss, thinning hair, dry skin and brittle nails. They all can reflect suboptimal thyroid function and affect your quality of life.

The importance and therapy for people with TSH lower than 10 mIU/L and normal T4 are a part of a continued debate and controversy in conventional medicine. Some studies argue for routine and some for selective therapy, however in the real life most doctors take the “wait and watch” approach and do not prescribe any treatment.

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10 Benefits of Borderline Hypothyroidism Treatment

Thyroid drug therapyMany research studies have pointed to some adverse effects of subclinical hypothyroidism and benefits of thyroid drug therapy:

1. Thyroid medication can slow down or stop progression to hypothyroidism in Hashimoto’s patients in the early stages of disease even if lab tests are normal.

Patients with borderline hypothyroidism have a high rate of progression to clinically overt hypothyroidism. However, it is different for each person, some people do not show progression and up to 10% of people with elevated levels of thyroid antibodies experience a spontaneous remission.

A TSH level greater than 10 mIU/L predicts a higher rate of progression, and a level of less than 6 mIU/L predicts a lower likelihood of progression to hypothyroidism.

Some research studies showed that prescribing a low dose of thyroid medication can delay or even prevent the progression of Hashimoto’s to hypothyroidism, reduce inflammation and stop the autoimmune attack on the thyroid.

2. Thyroid medication can help to decrease levels of thyroid antibodies to some degree.

This also will mean lower thyroid inflammation and possibly less profound autoimmune activity. Many people with Hashimoto’s disease don’t have any symptoms initially and are not getting diagnosed until they have hypothyroidism.

However, nearly 30% of patients with borderline hypothyroidism may have symptoms that suggest that they are deficient in thyroid hormones.

Increased odds for autoimmune thyroid disease are associated with positivity to TPO or Tb thyroid antibodies during the 2–7 years preceding the hypothyroidism diagnosis. During this time elevated thyroid antibodies are often the only sign that a person has Hashimoto’s disease.

Some research studies showed that prescribing a low dose of thyroid medication can to some degree lower high levels of thyroid antibodies.

While elevated thyroid antibodies can be one of early indicators of autoimmune thyroid disease it is possible to have Hashimoto’s thyroiditis with negative antibodies. In addition, low thyroid antibodies may not necessarily mean that you achieved a Hashimoto’s remission.

3. Thyroid medication can to some extent help to shrink the goiter.

Enlargement of the thyroid gland often accompanies or appears even before hypothyroidism is diagnosed. Thyroid medication can help to stop the growth of the thyroid and shrink the goiter.

4. People on thyroid medication can improve hypothyroid symptoms and overall well-being.

Many studies conducted on patients with TSH in a range from 3 to 32 mIU/L, showed improved symptoms, quality of sleep and memory in a quarter of patients.

5. Thyroid drugs can help to lower cholesterol levels and improve other cardiac risk factors.

Several studies showed an association of subclinical hypothyroidism with increased risk of heart disease, arteries plaque building and heart attack and confirmed reduction of LDL cholesterol and improvement in the lipid profile with thyroid drug therapy. Thyroid related high cholesterol levels are resistant to the cholesterol medication, however respond very well to the normalizing of the thyroid function and TSH levels.

This means if a person has low free T3 levels then it can result in poor  function of LDL receptors. This can increase the risk of heart disease due to elevated cholesterol and increased LDL particles number.

6. Improvement of muscle and nerve pain

Neuromuscular symptoms and dysfunction are very common in patients with borderline hypothyroidism and can be reversed by thyroid drug treatment and optimizing T3 levels.

7. Improvement of thyroid related depression, bipolar disorder and mental function.

Mild thyroid failure can aggravate bipolar disorder and depression that are associated with higher than normal TSH and T3 thyroid hormone in the lower normal range and show improvement after thyroid therapy. It is reasonable to have a low threshold for TSH levels for the borderline hypothyroidism treatment in patients with depression, bipolar disorder and mental dysfunction.

8. Thyroid drugs have positive effects on fetus development during pregnancy and treatment of infertility, un-ovulation and prevention of miscarriages.

Different normal TSH values are proposed for pregnancy because subclinical hypothyroidism and thyroid autoimmunity poses many risks for the health of mother and unborn baby including miscarriages, low baby weight and preterm delivery.

The normal range of TSH levels in the first trimester of pregnancy is 0.3 to 2.3 mIU/L. The upper limit of the normal TSH is 3.5 mIU/L in both the second and third trimesters of pregnancy that suggests that borderline hypothyroidism has to be treated.

Symptoms Of Underactive Thyroid

9. Treatment can stop weight gain and help to lose some weight.

Being outside of the normal range or even when your TSH is above 2.9 can slower down your metabolism and cause weight gain.

When you experience hypothyroid symptoms that are related to low metabolism such as cold hands, cold feet, hair loss, thinning of the outer third of your eyebrow, cravings for sweets and carbohydrates, fatigue and your TSH is elevated the chances are high that there is something going on with your thyroid gland or the ability of thyroid hormones to work properly.

Low metabolism in subclinical hypothyroidism is a very common reason why people cannot lose weight even on a restrictive diet and  with exercise. However, this can be corrected with a proper weight loss optimized thyroid treatment.

10. Prevention of heart disease, cancer, Alzheimer’s disease dementia and other degenerative disorders.

Even subclinical hypothyroidism can contribute to other health issues that can turn into chronic problems and is an increased risk of cardiovascular disease. I just give you an example how subclinical hypothyroidism or low thyroid function are contributing to atherosclerosis.

A recent study evaluated how LDL oxidation affects the development of arterial plaques and atherosclerosis. It found out that the LDL oxidation in people with borderline hypothyroidism can turn it into a more atherogenic form that contributes to atherosclerosis through the lipo-oxygenase pathway when a certain fatty acid oxidation products are produced during the LDL oxidation. These specific fatty acids are known to increase plaques and are reliable biomarkers of oxidative stress.

This study found out that there is also an association between lipid oxidation, TSH levels and biomarkers of subclinical atherosclerosis:

When the TSH goes up to 10 in borderline hypothyroidism there is a higher risk of atherosclerosis and it seems to be related to lipid peroxidation. 

When Borderline Hypothyroidism Should Be Treated

In conventional medicine treatment of borderline hypothyroidism depends only on the TSH levels, however this approach is not optimal for many thyroid patients and borderline hypothyroidism should be treated in most if not all cases.

Elderly patients and pregnant women in particular can benefit from an early subclinical hypothyroidism treatment to avoid potential consequences of untreated thyroid hormone deficiency.

The decision for thyroid drug therapy for people with TSH levels between 5.0 and 10.0 mIU/L but normal T4 should be individualized and can be especially recommended for the following groups:

  1. Pregnant women and women who are trying to get pregnant
  2. Patients with goiter
  3. People with hypothyroid symptoms
  4. Teenage girls with a delay of menstrual cycles
  5. Persistent and gradual increase of TSH
  6. Depression and bipolar disorder
  7. Infertility and un-ovulation
  8. Presence of thyroid antibodies and indication for Hashimoto’s disease
  9. High cholesterol
  10. Elderly people especially those who are at an increased risk for the development of atherosclerosis
  11. Low metabolism and inability to lose weight

According to current hypothyroidism treatment guidelines, all patients with subclinical hypothyroidism and TSH level above 10 mIU/L should be treated with thyroid drugs even if the free T4 is within normal laboratory range.

The strongest arguments for thyroid drug therapy when TSH is lower than 10 are:

  • High risk of progression to full-blown hypothyroidism
  • Possible improvement of quality of life
  • The fact that subclinical hypothyroidism is a cardiovascular risk factor

Natural Treatment For Subclinical Hypothyroidism

Functional medicine has a different approach to determine when a person has hypothyroidism and when thyroid treatment is required. It sets the upper TSH range limit substantially lower than conventional medicine.

This is based on the research studies showing that a normal TSH for people that don’t have any thyroid problems is somewhere between 0.5 and maybe 2.2 or 2.5 (depending on the study that you look at). This upper limit is an indicator for a more thorough investigation and extended thyroid testing that includes testing for thyroid antibodies.

If thyroid antibodies are high and indicate Hashimoto’s disease it can mean a totally different borderline hypothyroidism treatment approach. The main goal becomes to stop or at least delay the progression from Hashimoto’s disease to a full-blown hypothyroidism and it has to include understanding what could trigger thyroid and autoimmune disease and address these underlying issues first.

It is important to consider your age. The upper functional medicine TSH limit for elderly people is different than for younger people. More recent research is suggesting that in people who are in their 80s a TSH of above 3 is actually a normal value. This higher TSH number seems to reflect some age-related changes rather than issues with the thyroid gland itself.

Interestingly, one study even suggested that a higher TSH in people over 80 is associated with a lower total mortality. This means that when choosing treatment for the borderline hypothyroidism it is necessary to evaluate a person as a whole including the age, presence of autoimmune thyroid disease like Hashimoto’s and symptoms.

There is a strong evidence that treating borderline hypothyroidism can improve symptoms of heart disease and cardiovascular function. Back in the 60s and 70s doctors would use low dose of thyroid hormone replacement to treat high cholesterol. The reason for this was that one of many roles of T3 thyroid hormone is to activate the LDL receptor outside of the cells in order to allow LDL to be removed from the blood circulation, let LDL particles bind to receptors and enter the cells.

Some studies have shown that people even with TSH levels between 2.5 and 4.5 which would be considered normal in the conventional medical approach, show improvements in cardiovascular disease. This includes such risk factors as lipid profiles and endothelial cell function which translates into a better functioning blood vessels and decreased thickness of the blood vessels with improvement of thyroid function.

Does it mean that everyone needs a prescription for thyroid medication to treat subclinical hypothyroidism?

Not really. One study was watching 241 women who had borderline hypothyroidism and TSH levels between 4.5 and 10 for 5 years.  According to their findings, only 19% of women progressed to clinical hypothyroidism and had to take thyroid medication, in 23% of women TSH went back to normal spontaneously and over the half of women were still technically mild subclinically hypothyroid and weren’t prescribed thyroid drugs.

This indicates that only 1 out of 5 women actually required thyroid hormone replacement therapy and there are other factors that should be addressed first before reaching to thyroid drugs that can be even more effective.

The key is to find a balance between treating it right and not over-treating. Functional medicine focuses on bringing you back in balance by correcting the underlying cause of subclinical hypothyroidism and this doesn’t always mean the use of medication. This is especially true for the autoimmune thyroid disease.

Thyroid dietWhen treating borderline hypothyroidism caused by autoimmune thyroid disease, people with Hashimoto’s thyroiditis shouldn’t rely on thyroid medication alone.

Most triggers of thyroid autoimmunity are dietary and without addressing your diet and lifestyle modifications that aim to reduce toxicity in your life thyroid drugs have only limited effect or may even don’t help at all.

Hashimoto’s disease is an autoimmune condition when the problem is not with the thyroid gland but with the immune system. New research shows that in addition to genetic and environmental factors leaky gut plays the key role in the initiation of autoimmunity and the increase of thyroid antibodies.

People with subclinical hypothyroidism and elevated thyroid antibodies who start with dietary changes and healing of leaky gut early have the highest chances to stop autoimmune attack on their thyroid and go into a non-medicated remission.

If conventional medicine doesn’t offer you any thyroid treatment it doesn’t mean that there is nothing you can do. Learn about your options here


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1. Should we treat subclinical hypothyroidism? BMJ 2008; 337

2. Subclinical Hypothyroidism: An Update for Primary Care Physicians, Mayo Clin Proc. 2009 January; 84(1): 65–71.

3. Subclinical Hypothyroidism Is Mild Thyroid Failure and Should be Treated, McDermott and Ridgway 86 (10): 4585

4. Effects of Prophylactic Thyroid Hormone Replacement in Euthyroid Hashimoto’s Thyroiditis. Endocrine Journal 2005; 52(3):337-343

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About Marina Gutner, PhD

Marina Gutner, PhD, researcher, medical writer, thyroid blogger, founder and Admin of Outsmart Disease who writes about life-changing treatments for hypothyroidism, Hashimoto's thyroiditis and autoimmune disease and how to balance hormones in women