A recent study published in the New England Journal of Medicine examined the clinical benefits of levothyroxine in treating subclinical hypothyroidism in older adults. Previous studies conducted on subclinical hypothyroidism, which can have a large impact on patients and their daily lives, have been small, with limited evidence; this study delves further into the benefit of levothyroxine.

This double-blind, randomized, placebo-controlled, parallel-group study of 737 adults was conducted to determine the benefits that levothyroxine can have on an older patient with subclinical hypothyroidism. The study required that participants be aged 65 years or older and have subclinical hypothyroidism. The participants were randomized to two separate arms, and each arm contained similar baseline characteristics. One arm included 368 participants who received levothyroxine, while the other arm included 369 participants who received matching placebo. The study measured efficacy by determining the change from baseline to 12 months using the Tiredness score and the Thyroid-Related Quality-of-Life Patient-Reported Outcome (ThyPRO) symptom score.

Compared to placebo, at 12 months, there was a larger reduction in TSH levels from baseline in the levothyroxine group. At 12 months, the ThyPRO score, as well as the Tiredness score, was similar in the placebo group and the levothyroxine group. The results showed that even though there was improvement in thyroid function in the levothyroxine arm, the symptoms associated with thyroid function did not resolve in either study arm.

The researchers concluded that there were no symptomatic benefits in older patients when levothyroxine was used for treatment of subclinical hypothyroidism. Dr. David Scott, the study leader, stated “Our study concludes this treatment provides no apparent benefits for older adults and should therefore no longer be started routinely for this condition.”

On the other hand, hypothyroidism is more prevalent in older adults due to autoimmune thyroiditis, which is more common with advanced age. A study conducted by Keating et al  in 1961 consisted of 1,503 patients, the biggest to date, and it studied the effects of treatment of thyroid hormone in elderly patients with hypothyroidism. The study concluded that T4 treatment improved symptoms of angina. The researchers noted that older adults, especially those aged 65 years and older, often have coexisting conditions such as coronary heart disease and, most often, angina. Therefore, as the population ages, special care should be given to the elderly population with signs and symptoms of hypothyroidism while differentiating other comorbidities.

Since thyroid function can play a large role in a patient’s daily life, the study authors conclude, other causes of symptoms such as tiredness, weight gain, and lack of sleep should be further evaluated before prescribing levothyroxine in older adults based on the lack of symptomatic relief.

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