Introduction to Hypothyroidism
Hypothyroidism is a relatively common disorder. It affects more women than men, but Dr. Friedman happens to be one of the men who does have it. Symptoms of hypothyroidism include fatigue, gradual weight gain, constipation, muscle aches, joint pain, feeling cold, menstrual irregularities, weakness, hair loss, dry, cold skin and slow reaction time. Many patients will have a goiter (enlarged thyroid). Although it has received much discussion, low body temperature is not a reliable sign of hypothyroidism.
Causes of Hypothyroidism
The incidence of hypothyroidism increases with increasing age. In other words, the older we get, the more likely a thyroid deficiency will show up. The most common cause of primary hypothyroidism (hypothyroidism originating in the thyroid gland itself), is Hashimoto’s Thyroiditis. Hashimoto’s is an autoimmune condition, in which he body’s own antibodies attack the thyroid gland and destroy it, leading to hypothyroidism. Hashimoto’s Thyroiditis may be a manifestation of multiple autoimmune syndromes and may occur in families. Hypothyroidism can also be due to a pituitary problem (central hypothyroidism).
The Importance of Diagnosis
Diagnosing all types of hypothyroidism is important, because treatment with thyroid hormone will improve symptoms in patients with hypothyroidism, but is unlikely to help those who do not have hypothyroidism. In primary hypothyroidism, the thyroid gland, located in the neck, is less able to produce the thyroid hormones, T4 and T3. The pituitary gland, located at the base of the brain, responds to this deficiency by secreting more TSH. Thus, in more mild cases of primary hypothyroidism, T4 and T3 levels are normal, but the TSH is high. In more severe cases, T4 and T3 levels drop. Although the normal range for TSH is often between 0.5 and 5 mU/mL, values at the high end of the normal range may be abnormal. T3 is the more bioactive hormone compared to T4, but T4 is more stable in the circulation.
My approach to diagnosing hypothyroidism is to start with a careful history and physical. Then an Endocrinologist should perform a thyroid examination to determine if the patient has a goiter. Dr. Friedman is able to do this virtually. Blood TSH, free T4, free T3 and anti-TPO antibodies should be tested. Patients with an enlarged thyroid and/or a positive anti-TPO antibody test AND a TSH> 4.0 mU/mL should be considered to have primary hypothyroidism. Patients without an enlarged thyroid and without a positive anti-TPO antibody test but WITH a TSH> 7.0 mU/mL should also be considered to have primary hypothyroidism. Because the TSH varies, an elevated test should be repeated before treatment with thyroid medicine is started. Patients with a free T4 of < 0.9 ng/dL and a TSH< 1.0 mU/mL may have central hypothyroidism, especially if they had damage to their pituitary. Patients with symptoms of hypothyroidism but who do not meet these criteria should be watched, other causes of their symptoms should be sought, and retesting should occur in 6 months.
Hypothyroidism Treatment
Once hypothyroidism is diagnosed, there are many treatment options, including synthetic L-thyroxine (T4) preparations (levothyroxine, Tirosint, Synthroid, Levoxyl and Unithroid), synthetic L-triiodothyronine (T3) preparations (Cytomel), and desiccated thyroid extract (DTE) preparations (Armour, NP thyroid, Erfa and Adthyza). All of the L-thyroxine preparations contain the same active ingredient but contain different fillers and have different quality control.
Most Endocrinologists use L-thyroxine preparations for the initial treatment of all forms of hypothyroidism. Although the use of L-thyroxine (T4) compared to L-triiodothyronine (T3) may be surprising as T3 is the more bioactive thyroid hormone, T4 is most frequently used. This is because tissues convert T4 to T3 to maintain physiologic levels of the T3. Thus, administration of T4 results in bioavailable T3 and T4. As T4 is more stable than T3, T4 therapy gives even blood levels, while T3 therapy leads to high levels after taking the medicine and low levels before the next dose. There is growing interest in using T4/T3 combinations and DTE preparations in patients that are not doing well on L-T4 treatment.
Personalized Treatment Considerations: What is in the literature
A classic study published in New England Journal of Medicine in 1999 suggested that brain T4 to T3 conversion may be impaired in some patients and that a select group of patients should be treated with both T4 and T3. Studies have found that 15% to 20% of patients on L-T4 that have a normal TSH still have hypothyroid symptoms. Most patients who come to see Dr. Friedman have been put on L-T4 replacement and are still symptomatic and looking for a response other than “your TSH is normal, there is nothing else I can do.”
In the May 2013 issue of Journal of Clinical Endocrinology and Metabolism http://www.ncbi.nlm.nih.gov/pubmed/23539727, Hoang and colleagues from the Walter Reed Medical National Military Medical Center in Bethesda, Maryland published the results of a randomized crossover study in which 70 patients completed the study and received either desiccated thyroid (Armour) or levothyroxine replacement. There was a 2.9-pound weight loss among the group that took the desiccated thyroid compared to the levothyroxine group that was significant. Most importantly, 49% of the patients preferred Armour Thyroid, 19% preferred levothyroxine and 33% did not notice a difference. They had better well-being and their thyroid symptoms were significantly better with better cognitive function on Armour Thyroid compared to when they were on levothyroxine.
This study was confirmed by Shakir and colleagues (Shakir MKM, Brooks DI, McAninch EA, et al. Comparative Effectiveness of Levothyroxine, Desiccated Thyroid Extract, and Levothyroxine+Liothyronine in Hypothyroidism. J Clin Endocrinol Metab. 2021;106(11):e4400-e4413). who randomized patients to L-T4, L-T4 + L-T3, or DTE for 22 weeks. They found quality of life outcomes were similar among hypothyroid patients taking DTE vs L-T4 +L-T3 or L-T4 alone. Overall, 45% of patients indicated they preferred desiccated thyroid as their first choice of treatment, 32% preferred LT4/T3 as their first choice, and 23% preferred LT4 alone. However, those patients that were most symptomatic on L-T4 preferred and responded positively to therapy with L-T4 + L-T3 or DTE.
These two studies suggests that a subset of patients do better on DTE as opposed to levothyroxine alone. Are you one of those patients?
Dr. Friedman is the master at using desiccated thyroid preparations, either alone or with other thyroid hormone preparations. Dr. Friedman aims for a free T4 and free T3 in the upper-normal range.
Patients with central hypothyroidism can be treated with any of the preparations available for patients with primary hypothyroidism. The difference is that treatment needs to be monitored by aiming for a free T4 and free T3 in the upper-normal range, as TSH is suppressed with proper treatment. Patients with both central and primary hypothyroidism also needed to be treated by aiming for a free T4 and free T3 in the upper-normal range.
A Personal Case Study
I was diagnosed with primary hypothyroidism in February 2003. An Endocrinologist performed an examination of my thyroid gland, and I was found to have a goiter. My blood values showed a TSH of 8 mU/mL and strongly positive anti-TPO antibodies. I have a strong family history of Hashimoto’s Thyroiditis, but I was lucky to be fairly asymptomatic prior to treatment. I take Tirosint plus twice daily Cytomel and feel great.
Contact Dr. Friedman for a Consultation
For more information about Dr. Friedman’s Endocrinology clinic, visit his website at www.goodhormonehealth.com.