What is a normal TSH in the elderly?

An 80-year-old man came to see me regarding elevated thyroid-stimulating hormone. Over the past 5 years, his TSH has varied between 5 mU/L and 9 mU/L. His primary care physician advised initiation of thyroid hormone replacement therapy. However, the patient felt well. He did not have fatigue, weight gain or other symptoms possibly due to hypothyroidism. He was mentally alert and physically active; indeed, he still occasionally went for a jog. He did not have a goiter or thyroid nodules.

Because he did not have any symptoms he asked me whether it was absolutely necessary for him to begin thyroid hormone therapy or if we should hold off.

Subclinical hypothyroidism has been associated with a variety of symptoms, metabolic abnormalities and an increased risk for progression to overt hypothyroidism. Some have suggested that the upper limit of normal for TSH be decreased to 3 mU/L. In my own practice, I treat patients with hypothyroidism to a target TSH within lower half of normal.

In those who present with high normal TSH, I may also consider treatment, especially in specific circumstances. This includes young women who plan to become pregnant, those with high titer of anti-thyroidperoxidase antibody, those with goiter or thyroid nodules, as well as anyone who has symptoms that may possibly be due to hypothyroidism.

The elderly, however, may be different. In the oldest of old, elevated TSH might not be as much of a concern as we had previously thought. In the Netherlands, a prospective population-based study of 599 participants assessed the long-term impact of abnormal thyroid function on performance and survival in old age. Beginning at age 85 years, activities of daily living, cognitive performance and depressive mood were evaluated annually through age 89 years. The study found no association with disability in activities of daily living, depressive symptoms or cognitive impairment related to abnormal TSH or thyroxine levels. A surprise: the study observed that a higher TSH was actually associated with increased survival.

What is a “normal” TSH in the oldest of old?

Should the target range for TSH in the elderly being treated with thyroid hormone differ from that of other populations?

Without a randomized, placebo-controlled, clinical trial we cannot know the answer to these questions for certain. When I am presented with someone over age 80 years who has mildly elevated TSH and is asymptomatic, I am willing to observe if there is no other indication to treat and that is the patient’s preference. I would not hesitate to initiate therapy in someone with elevated TSH with or without symptoms of hypothyroidism who desires treatment, however, no matter what their age.

After explaining our options, the patient chose to be followed by observation. We do have an understanding that if he develops symptoms or his TSH continues to trend upward, we will again discuss therapy.

For more information:

Gussekloo J. JAMA. 2004;292(21):2591.