Hypothyroidism: A Functional Medicine Perspective

An earlier article in this series described how the thyroid works and how to read thyroid tests. This article turns to the clinical questions practitioners actually face: when mild thyroid abnormalities need treatment, how treatment is optimised, why some treated patients still feel unwell, and where a functional perspective adds most value without straying into decisions that belong with the prescriber.

Causes, in order of frequency

The symptom problem

The classic symptoms of hypothyroidism, fatigue, weight gain, cold intolerance, constipation, dry skin, hair thinning, low mood and slowed thinking, are among the most common complaints in any population. Studies comparing people with and without hypothyroidism have found that many of these symptoms are only modestly more frequent in those with the disease. This has 2 implications. Testing is appropriate when these symptoms are present, but a normal thyroid result should prompt a search for other causes rather than repeated thyroid testing. And when thyroid disease is present, it may not explain all of a patient’s symptoms.

Subclinical hypothyroidism: to treat or not

Subclinical hypothyroidism, a raised TSH with normal free T4, is common, particularly in women and older adults. Decisions about treatment depend on several factors.

• Confirm first. TSH varies, and a single mildly raised value often normalises on repeat testing a few months later, particularly after illness.
• TSH above 10 mU/L is generally considered an indication for treatment, because of the higher risk of progression and cardiovascular effects.
• TSH between the upper reference limit and 10 mU/L in older adults: a randomised trial in adults aged 65 and over found that levothyroxine did not improve symptoms or quality of life compared with placebo. Watchful monitoring is often appropriate.
• Younger adults with symptoms may be offered a trial of treatment, with review of whether symptoms improve.
• Pregnancy and planning pregnancy warrant specific thresholds and closer attention, managed by the treating clinician.
• Positive thyroid peroxidase antibodies increase the likelihood of progression and support closer monitoring.

Treatment and its fine details

Levothyroxine is the standard treatment. Full replacement doses are commonly estimated at around 1.6 micrograms per kilogram per day in adults without heart disease, while older adults and people with cardiac disease usually start lower and increase gradually. TSH is rechecked several weeks after each change until stable, then periodically.

Practical factors often determine whether treatment works:

• consistent timing, typically on an empty stomach, separated from food and coffee as advised;
• separation from calcium, iron, magnesium, some antacids and fibre supplements;
• awareness that proton pump inhibitors, coeliac disease, Helicobacter pylori infection and other malabsorptive conditions can increase dose requirements;
• consistency of brand or formulation, as switching can alter levels in some people;
• pausing biotin before testing to avoid falsely abnormal results;
• adjustments during pregnancy, with changes in weight and when starting or stopping oestrogen containing medicines.

The risks of overtreatment

Taking more thyroid hormone than needed, whether through excessive prescribed doses, self adjustment or over the counter thyroid products, causes subclinical or overt hyperthyroidism. This increases the risk of atrial fibrillation and, particularly in postmenopausal women, loss of bone density and fractures. Studies suggest that a meaningful proportion of people on levothyroxine have a suppressed TSH. Practitioners should be alert to patients who have increased their own dose or are taking thyroid glandular supplements, some of which have been found to contain thyroid hormone.

When symptoms persist despite normal TSH

Surveys suggest that a minority of patients with hypothyroidism who have normal TSH on levothyroxine continue to report symptoms such as fatigue and poor concentration. Several explanations are possible, and more than one may apply.

Coexisting conditions

This is where a functional approach adds the most value. Conditions that commonly accompany hypothyroidism and cause similar symptoms include:

Suboptimal treatment

Absorption problems, inconsistent timing or interactions can leave TSH at the edge of target.

Combination therapy

Some patients report feeling better on a combination of levothyroxine and liothyronine, T3. Trials comparing combination and levothyroxine alone have generally not shown consistent advantages, although some patients preferred combination therapy. International thyroid societies have concluded that combination therapy is not recommended routinely but may be considered on a trial basis in selected patients who remain symptomatic despite optimal levothyroxine, under specialist supervision. Desiccated thyroid extract is not recommended by major guidelines because of variable T3 content.

The functional contribution

A functional approach to hypothyroidism does not involve changing thyroid medication independently or treating people with normal thyroid function. It involves:

1. building the timeline, which may reveal pregnancy, stress, iodine intake changes or medicines relevant to onset;
2. checking and correcting coexisting nutrient deficiencies;
3. screening for associated conditions such as coeliac disease and sleep apnoea;
4. helping patients take levothyroxine effectively;
5. addressing sleep, activity, diet and stress, which influence symptoms regardless of thyroid status;
6. communicating findings to the prescriber.

An illustrative case

A 49 year old teacher treated for hypothyroidism for 6 years has a normal TSH but remains exhausted and has gained weight. She has read that she needs T3 and wants to change her treatment. Her timeline shows that her fatigue worsened 2 years ago, around the time her periods became irregular and her sleep deteriorated.

Her assessment finds a low ferritin, low vitamin D and a positive coeliac serology, confirmed on biopsy. She is also perimenopausal, with night sweats disrupting sleep. Her doctor treats her iron and vitamin D deficiency, a gluten free diet is started with a dietitian, and her menopausal symptoms are managed. Her levothyroxine dose is adjusted as absorption improves on the gluten free diet. 6 months later her energy is much better. Her thyroid treatment had been adequate; 3 other conditions had been keeping her unwell.

Thyroid care as team care

Hypothyroidism is one of the most satisfying conditions to treat when the diagnosis is clear and replacement is well managed, and one of the most frustrating when symptoms persist. The difference is often made by looking beyond the thyroid, at the nutrient deficiencies, associated autoimmune conditions, sleep, mood and life stage changes that frequently accompany it.