December 10, 2024, 3:42 pm | Read time: 4 minutes
Many people with a known underactive thyroid (technical term: hypothyroidism) take medication to compensate for the lack of endogenous hormones. This is intended to alleviate the undesirable side effects of their actual condition. However, it appears that a side effect of thyroid medication itself can be just as serious – even if it is taken in the recommended amount. This is shown by a recent study.
The thyroid gland is colloquially known as the “engine of the body.” The hormones it produces are responsible for regulating numerous metabolic processes – the organ influences the entire cardiovascular and nervous system as well as the calcium balance, among other things1 If the thyroid gland is underactive, this can lead to various metabolic complaints, depending on the severity. These include possible weight gain, lack of concentration and fatigue, sensitivity to cold, and much more. A common treatment is the administration of a thyroid medication, and regular monitoring of the dosage makes sense. However, it may also have undesirable side effects in the long term if it is taken as recommended. Radiologists and endocrinologists at Johns Hopkins University came to this conclusion in a joint study.
Overview
Study on Thyroid Medication and Its Side Effects
The reason for the study was the assumption “that a significant proportion of thyroid hormone prescriptions are given to older adults without hypothyroidism.” This is how study author Dr. Elena Ghotbi puts it in a recently published press release2 This careless use of thyroid medication has raised questions about how taking the medication could affect those treated in this way. The answer could be that it has undesirable consequences for bone health.
Bone Loss Due to Taking Levothyroxine?
“Our study suggests that levothyroxine use appears to be associated with greater bone loss in older adults, even when current guidelines are followed.” Lead study author Shadpour Demehri explains in the publication that ‘guidelines’ refer to the general reference values for healthy thyroid hormone levels.
For their study, the researchers used data from the Baltimore Longitudinal Study of Aging (BLSA), one of the oldest and most comprehensive studies of aging3 They focused on women and men aged 65 and older with thyroid levels in the normal range. In 81 of them, these were due to the intake of medication. In contrast, 364 of the test subjects had not taken any thyroid medication during the period under review. The researchers measured the bone density of the senior citizens in at least two examinations during the course of the study.
It is generally normal for bone density to decrease with increasing age. This is generally at its highest around the age of 30. From the mid-30s, around one percent of bone mass is lost every year. Dr. Ghotbi and her colleagues wanted to find out whether taking the thyroid medication levothyroxine has the side effect of promoting natural bone loss.
Results and Their Significance
The analysis showed – also taking into account other known risk factors for bone health – that taking levothyroxine was associated with higher bone density loss. This also applied to subjects who had been helped by the medication to achieve TSH values in the normal range. The effect developed on average over a follow-up period of around 6.3 years.
Based on their findings, the researchers responsible urge close monitoring of drug treatments for hypothyroidism. “A risk-benefit assessment should be performed,” they explain, “in which the strength of the indications for treatment are weighed against the potential adverse effects of levothyroxine (…).” In terms of risks, the researchers are referring to the decrease in bone density as a risk factor for osteoporosis. The finding is associated with a greatly increased fragility of the bones and should therefore be taken seriously. As a preventative measure, it is advisable to eat a diet that is geared towards bone density and to get enough physical activity. Strength training, in particular, is considered beneficial.
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Notes from the Editors
It is generally advisable to avoid taking medication unless necessary. For mild hypothyroidism, a diet rich in iodine and selenium may sometimes stimulate the thyroid and potentially reduce the need for medication.
However, the knowledge of possible side effects should never prompt you to treat yourself or stop taking your prescribed medication without consulting a doctor. This is because massive hypothyroidism can have serious consequences if left untreated. The absence of these hormones can impair critical organ functions, potentially leading to life-threatening consequences. If you have any concerns, be sure to talk to your doctor.