IBS and Hypothyroidism

Published date: March 15, 2012 | Modified date: July 24, 2019

Hypothyroidism is a serious health condition found in people both with and without food allergies. People with food allergies, including those with celiac disease (a gluten allergy), frequently suffer from hypothyroidism.

What Is the Thyroid Gland?

The thyroid gland sits in the neck in front of and on both sides of the trachea and produces thyroid hormones. The thyroid is small and shaped like a butterfly and the hormones it secretes regulate metabolism and thus affects many aspects of health.

What Is Hypothyroidism?

Hypothyroidism is a condition in which the thyroid gland does not produce adequate thyroid hormones, which are triiodothyronine (T3) and thyroxine (T4). Thyroid hormones are critical to health, contributing to metabolic rate, energy, and cognitive function.

The opposite of this condition is hyperthyroidism, where the thyroid gland produces too much of the thyroid hormones.

Causes of Hypothyroidism

Several factors can prevent the thyroid gland from producing thyroid hormones. The most common cause is an autoimmune condition called Hashimoto’s thyroiditis that attacks the thyroid gland.

Other common causes of hypothyroidism are:

  • Over-response to hyperthyroid treatment
  • Thyroid surgery
  • Radiation therapy of the thyroid
  • Some medications

IBS and Hypothyroidism

What Are the Symptoms of Hypothyroidism?

Hypothyroidism causes fatigue and weight gain as well as other problems. Complexities in thyroid testing and symptoms which may overlap or contradict food allergy symptoms can lead to physicians often overlooking and misdiagnosing hypothyroidism.

There are several different types of hypothyroidism, but in most cases, people who have a hypothyroid condition will feel tired, lack focus, and may experience dry skin, cold extremities, constipation, depression, or weight gain. Hypothyroidism can also cause problems with lipids, infertility, and neuromuscular problems.

Other medical conditions can be present at the same time and may mask many of these symptoms. For example, hypothyroidism is commonly associated with celiac disease, which may cause diarrhea. When that happens, no one suspects hypothyroidism, because it causes constipation, not diarrhea.

Testing for Hypothyroidism

Most physicians measure thyroid function not by testing hormones produced by the thyroid, but by testing levels of TSH or thyroid-stimulating hormone. The pituitary gland produces TSH and stimulates the thyroid gland to produce thyroid hormones.

As thyroid hormone production drops, TSH levels normally increase to compensate for low thyroid hormone levels. Therefore, a higher than normal TSH level indicates a hypothyroid condition.

In theory, this works well for evaluating thyroid function. Unfortunately, many physicians are using an outdated and unnecessarily wide reference range when determining normal TSH levels. Because of this, you may be hypothyroid even when your physician tells you your thyroid level is normal.

A normal TSH level is between 0.30 and 2.5 as determined by the American Association of Clinical Endocrinologists. However, many physicians and labs are using an older standard with a range of 0.30 to 5.00. Therefore, your TSH level may increase to what appears to be a very normal looking 3.00, when you may be quite hypothyroid.

For a more accurate result, an initial evaluation of thyroid function must include not only TSH, but thyroid hormones as well. Whenever there is a diagnosis of hypothyroidism, or when the TSH level fluctuates, it is also important to measure autoimmune thyroid antibodies. This is especially true for people with food allergies and intolerances since there is a higher association of autoimmune hypothyroidism in these people.

Why Does Hypothyroidism Frequently Go Undiagnosed?

Unfortunately, TSH doesn’t always respond correctly to low thyroid hormone levels. If tests do not check for the actual thyroid hormones themselves, physicians can miss hypothyroidism. Autoimmune thyroid problems can also interfere with thyroid function without changing TSH levels. We’ve seen many cases of hypothyroidism with low thyroid hormone production and a normal TSH level.

IBS and Hypothyroidism

Treating Hypothyroidism

Hypothyroidism is usually readily treatable, but there are several factors to consider when evaluating thyroid function.

The most common treatment for hypothyroidism is levothyroxine or T4. Levothyroxine is also known under the brand names Synthroid and Levoxyl. T4 is then converted by the body into T3, the active thyroid hormone. Levothyroxine is identical to the T4 hormone that your body makes and is usually very effective at correcting hypothyroidism.

Physicians sometimes prescribe T3 (Cytomel), which may also be helpful for treat cases of hypothyroidism when the body is not adequately converting T4 into T3. This may be done for patients who are not responding well to levothyroxine (T4) therapy.

They’re also nutritional ways to support the thyroid, as well as other types of thyroid hormone replacement that some patients find beneficial. Armour thyroid and Nature Thyroid are two types of desiccated glandular thyroid replacement options sometimes prescribed to treat hypothyroidism. Glandular products mean that they are from a ground-up porcine gland. They contain both T4 and T3, as well as the other constituents of the thyroid gland.

After starting thyroid treatment, it is important to monitor thyroid levels regularly to make sure the prescribed dosage is correct. This is particularly true in people with autoimmune thyroid conditions and those with newly diagnosed food allergies and intolerances, as their thyroid levels are susceptible to frequent swings. But everyone prescribed thyroid medication should get their thyroid checked monthly until their thyroid levels have returned to normal.

How Does Treatment of Hypothyroidism Impact IBS?

Hypothyroidism is found in a subset of patients with IBS. It can mask the symptoms of IBS, or even be the cause of IBS if not properly diagnosed and treated.

Hypothyroidism often causes constipation. This may be misdiagnosed as IBS of the constipation variety. On the flip side, treating hypothyroidism may relieve constipation only to result in diarrhea. It may appear the patient is being overtreated because too much thyroid can cause diarrhea. However, the treatment dose may be correct, and relieving constipation may have unmasked a problem of IBS with diarrhea, which had previously been hidden by constipation resulting from hypothyroidism.

Another example of the thyroid treatment dose being correct but digestive problems not improving is when hypothyroidism is properly treated but the constipation remains. In this case, constipation is being caused by IBS and will not resolve until both the hypothyroidism and the IBS are properly treated.

In complex cases like these, it is very helpful to have a physician who understands and appreciates both of these conditions and can help you sort them out.

Hypothyroidism and Food Allergy Case Studies

This is one of the most underappreciated causes of hypothyroidism. We often see patients who have both hypothyroidism and food allergies/intolerances and would like to share some case studies.

  • Case #1: 30-year-old woman with complaints of fatigue, weight gain, and forgetfulness. These symptoms had become progressively worse over the last two years. The patient was previously told her thyroid was normal. Re-testing showed she was suffering from hypothyroidism. Treatment with thyroid hormone completely solved her energy shortage resulting in weight loss and much better cognitive function.
  • Case #2: 40-year-old man complaining of fatigue, sluggishness, weight gain, and constipation. Testing showed that he had a hypothyroid condition. Treatment with thyroid hormones quickly turned around his fatigue, resolved constipation, and made it possible for him to lose weight.
  • Case #3: 51-year-old woman diagnosed with hypothyroidism two years ago and recently diagnosed with celiac disease. TSH testing showed fluctuating thyroid levels for over two years, resulting in repeated changes in the dosage of thyroid medication. More recent testing demonstrated high autoimmune thyroid antibodies, explaining the fluctuations in thyroid levels. This patient continued to experience abdominal pain, nausea, and weight loss until a diagnosis of celiac disease. Avoidance of gluten also helped to stabilize her thyroid problem.
  • Case #4: 35-year-old man diagnosed with gluten sensitivity approximately 2.5 years ago. He was very tired and had trouble focusing and remembering. He was also approximately 50 pounds overweight. Lab tests revealed significant hypothyroidism and very high thyroid antibodies. Thyroid medication has quickly begun to restore his energy and clarity of thought and he is doing much better.
  • Case #5: 70-year-old woman diagnosed with hypothyroidism several years after receiving a celiac disease diagnosis. She continued to experience many problems, including fatigue, weight loss, and diarrhea, until both problems were diagnosed and properly treated.
  • Case #6: 12-year-old girl diagnosed with hypothyroidism and being treated for it. She came in to see us for her IBS. After treating her IBS and removing her food allergies/intolerances (including dairy) from her diet, her TSH improved and she was able to get off her thyroid medication. Her parents were thrilled (as were we!) and are very grateful.

If you are concerned about the possibility of having hypothyroidism, have digestive problems, or are wondering about the interpretation of previous lab results, please call the IBS Treatment Center to schedule an appointment for a thorough evaluation of your thyroid function.