Clinical Thyroidology for the Public summarizes selected research studies discussed in the previous month’s issue of Clinical Thyroidology, an official publication of the American Thyroid Association. Editor-in-chief, Alan Farwell, MD, FACE

Volume 15 Issue 12

December is Hyperthyroidism Awareness Month

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Clinical Thyroidology for the Public Volume 15 Issue 12 (PDF file, 2.56 MB)



Are there long-term adverse effects of L-T3 therapy for hypothyroidism?

L-T4 effectively controls biochemical and clinical features of hypothyroidism in most individuals. A trial of L-T4 and L-T3 combination therapy can be considered in patients with continued symptoms on L-T4 alone and may result in improvement in symptoms. The aim of the present study was to compare the risk of osteoporosis, atrial fibrillation, cancer risk, and mood disorders in patients treated with L-T4 alone versus L-T3 therapy (either alone or in combination with L-T4) in a large patient groups in Korea.
Yi W et al 2022 Heart failure and stroke risks in users of liothyronine with or without levothyroxine compared with levothyroxine alone: A propensity score-matched analysis. Thyroid 32:764–771. PMID: 35570696.

A history of hypothyroidism is associated with higher dementia risk in elderly Asians

Dementia is a brain disease that causes memory loss, more commonly seen in the older people, and cases are increasing through the years. Because of these similar symptoms with hypothyroidism, there has been increasing interest in exploring the role of thyroid function in dementia. This study examines possible link between hypothyroidism and dementia in the East Asian people.
Wieland DR et al 2022 Thyroid disorders and dementia risk: A nationwide population-based case-control study. Neurology. Epub 2022 Jul 6. PMID: 35794019.

What is the risk of missed cancer in the longterm follow-up of thyroid nodules?

Thyroid nodules are common and up to 65% of the adult population being expected to have this condition. The cancer risk of thyroid nodules has been estimated to be 5-15%, based on prior studies. This study aimed to assess the cancer rate of thyroid nodules larger than 1 cm in diameter diagnosed by ultrasound during long-term follow-up of up to 23 years.
Grussendorf M et al. Malignancy rates in thyroid nodules: a long-term cohort study of 17,592 patients. Eur Thyroid J. 2022 Jun 29;11(4):e220027. doi: 10.1530/ETJ-22-0027.

Delayed radioactive iodine therapy does not impact response or survival in patients with thyroid cancer

Radioactive iodine therapy is considered in patients with intermediate or high risk thyroid cancers to decrease the risk of thyroid cancer recurrence. Following thyroid surgery, patients typically spend the first two weeks recovering before they receive radioactive iodine therapy at 6-10 weeks. The goal of this study was to determine whether a delay of more than 3 months in administering radioactive iodine after thyroid surgery would affect how well the thyroid cancer responded to treatment.
Cheng F et al 2022 Delay of initial radioactive iodine therapy beyond 3 months has no effect on clinical responses and overall survival in patients with thyroid carcinoma: A cohort study and a meta-analysis. Cancer Med 11:2386– 2396. PMID: 35179295.

Radioactive iodine therapy for patients with Graves’ disease with positive TPO antibodies is associated with early hypothyroidism

Radioactive iodine therapy is frequently used to treat Graves’ disease. A number of factors have been associated with rates of hypothyroidism after radioactive iodine therapy. The authors sought to determine whether the presence of positive anti-TPO was associated with the subsequent development of hypothyroidism after radioactive iodine therapy.
Verdickt S et al 2022 TPO antibody status prior to first radioactive iodine therapy as a predictive parameter for hypothyroidism in Graves’ disease. Eur Thyroid J 11(4):e220047. PMID: 35687484.

What is a useful cutoff of TSH-receptor antibody level in pregnant women with low TSH level in early pregnancy?

The most common cause of hyperthyroidism in pregnancy is Graves’ disease, where high levels of TSH-receptor antibody (TRAb) cause thyroid gland to make too much thyroid hormone. Since low TSH levels can occur in normal pregnancy, it is sometimes difficult to tell apart normal transient low TSH levels from Graves’ disease. A key part of the diagnosis depends on the presence of TRAb levels. The researchers of this paper studied how often TRAb levels were elevated and how often they were associated with low TSH levels.
Udall Torp NM et al 2022 TSH-receptor antibodies in early pregnancy. J Clin Endocrinol Metab. Epub 2022 Jun 23. PMID: 35737956.