Clinical Thyroidology® for the Public

Summaries for the Public from recent articles in Clinical Thyroidology
Table of Contents | PDF File for Saving and Printing

HYPOTHYROIDISM
TSH spontaneously normalizes in many older adults with subclinical hypothyroidism

11

Instagram Youtube LinkedIn Facebook Twitter

 

BACKGROUND
Subclinical hypothyroidism is a mild form of hypothyroidism defined by TSH levels above the normal range and normal thyroid hormone (FT4) levels in the blood. TSH is a pituitary hormone that is very sensitive to changes in thyroid hormone levels. In the early stages of hypothyroidism, TSH levels increase before the thyroid levels become low. However, sometimes mildly elevated TSH levels normalize after a few months. This study was done to better understand how common this normalization occurs, and which patients are more likely to normalize.

THE FULL ARTICLE TITLE
 Van der Spoel E et al 2023 Incidence and determinants of spontaneous normalization of subclinical hypothyroidism in older adults. J Clin Endocrinol Metab. Epub 2023 Oct 20:dgad623. PMID: 37862463.

SUMMARY OF THE STUDY
This study looked at individuals older than 65 years old from four different European countries (UK, Netherlands, Switzerland and Ireland). At the beginning of the study all the patients had mildly elevated TSH levels: 4.6-19.9 mIU/L and normal FT4 levels. The study looked at TSH over time.

The authors studied two groups of patients: the first group (2335 patients) had one single elevated TSH value at the beginning of the study and a repeat test at one year. Their average age was 72, 60% were women and their average TSH level was 5.4.

The second group (361 patients) had two abnormal TSH levels tested about three months apart, confirming persistent subclinical hypothyroidism, and a third TSH level tested after 1 year. Their average age was 75, 52% were women and the average TSH level was 5.75. None of these patients received treatment with thyroid hormone.

In the first group, 60% of the patients had normal TSH levels when retested at one year. This was even more common among younger patients, female patients and those who had lower initial TSH and higher FT4 levels. TSH normalization was also more common if the second measurement was done in the summer months. In the second group, 40% of the patients had normal TSH levels at one year. The patients most likely to have normal TSH levels at one year were younger, female, had initial lower TSH and higher Ft4 levels and had negative TPO (thyroid peroxidase antibodies).

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that, among people older than 65 years old, TSH levels in the subclinical hypothyroid range commonly normalize over time without treatment. Clinicians should measure TSH levels at least twice before recommending treatment. In addition, a third TSH measurement over time, particularly for those patients who are most likely to normalize, such as women and those with minimal TSH elevations, may be helpful in order to avoid unnecessary treatment.

— Susana Ebner MD

ABBREVIATIONS & DEFINITIONS

Subclinical Hypothyroidism: a mild form of hypothyroidism where the only abnormal hormone level is an increased TSH. There is controversy as to whether this should be treated or not.

Hashimotos thyroiditis: the most common cause of hypothyroidism in the United States. It is caused by antibodies that attack the thyroid and destroy it.

TSH: thyroid stimulating hormone — produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally.

TPO antibodies: these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.

Table of Contents | PDF File for Saving and Printing