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Standardized dosing needed for thyroid hormone extract
Treatment with thyroid hormone extract should be standardized and regulated by the FDA to diminish reported adverse events, according to a survey of physicians who manage patients with thyroid disease published in Endocrine Practice.
“It is important to provide a broader understanding of issues that may arise from the use of the thyroid extract products among physicians, pharmacists and patients to achieve optimal treatment for hypothyroidism,” the researchers wrote. “Clinicians prescribing thyroid hormone extract preparations should be reminded that these products are not harmless as many ‘natural’ remedies are assumed to be by a portion of the lay public.”
James V. Hennessey, MD , FACP, of the division of endocrinology at Beth Israel Deaconess Medical Center, and colleagues conducted a survey-based study of 1,536 members of the American Thyroid Association, Endocrine Society and American Association of Clinical Endocrinologists to determine the rates of adverse events in people with thyroid disorders treated with thyroid hormone extract. Overall, 63% of survey participants reported no adverse events associated with thyroid hormone products in their patients.
Among 565 reported adverse events, 59% occurred in patients treated with levothyroxine, 31% in patients treated with thyroid hormone extract and 9% in patients treated with liothyronine. After exclusion, adverse events in liothyronine users were not analyzed further, and 91 adverse events in thyroid hormone extract users remained.
Adverse events were due to new or unexpected symptoms in 16% of the thyroid hormone extract users, to a thyroid-stimulating hormone change alone in 15% and to both in 68% of the 91 adverse events among thyroid hormone extract users. Thyrotoxicosis was the most common symptom (65%); two participants experienced arrhythmias, and 5% had symptoms typical of hypothyroidism.
“Based on the relative frequency of extract prescriptions and levothyroxine prescriptions, the number of adverse event reports received from endocrinologists is higher with extract than with thyroxine,” Hennessey told Endocrine Today. “It would seem that patients treated with extract are referred to endocrinologists when they have persistent symptoms — which may not be related to a deficiency of thyroid hormone — and their primary care physicians encounter difficulties adjusting doses because of confusing thyroid function testing. Frequently, the non-specificity of these symptoms is not appreciated and thyroid hormones are prescribed in excessive amounts when other medical conditions are responsible for the symptoms. This results in medical complications due to too much thyroid hormone and no resolution of the symptoms as the root cause of the symptoms is not addressed. Additional symptoms may occur as the underlying condition goes untreated while the patient insists that all symptoms must be due to thyroid problems.” – by Amber Cox
For more information:
James V. Hennessey, MD, FACP, can be reached at Director of Clinical Endocrinology, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215.
Disclosure: The researchers report no relevant financial disclosures.