Thyroid blog

Studies have reported an increasing incidence of thyroid cancer since 1980. One possible explanation for this trend is increased detection through more widespread and aggressive use of screening tests. Researchers at the American Cancer Society analyzed thyroid cancer incidence between 1988 and 2005 using the National Cancer Institute’s (NCI’s) Surveillance Epidemiology and End Results (SEER) dataset.

They found incidence rates increased for all sizes of tumors, suggesting that screening is not the only explanation for the rise. The highest rate of increase was for primary tumors smaller than 1.0 cm, which rose nearly 10 percent per year among men from 1997 and 2005, and nearly 9 percent/year from 1988 to 2005 among women. Incidence of tumors 4 cm or larger increased more than 3.5 percent per year from 1988 to 2005 among men and 5.7 percent per year from 1988 to 2005 among women.

The authors conclude that incidence rates of differentiated thyroid cancers of all sizes increased between 1988 and 2005 in both men and women, and that the increased incidence across all tumor sizes suggests that increased detection through testing is not the sole explanation. Other explanations, including environmental influences and molecular pathways, should be investigated.

Cholesterol-lowering statins, used by millions of Americans to treat and prevent atherosclerosis, may falsely indicate thyroid problems, according to researchers at Texas Health Presbyterian Hospital Dallas.

Their study, "Radioiodine studies, low serum TSH, and the influence of statin drugs," appears in the journal Thyroid.

"These findings could help physicians make quicker, more accurate diagnoses of suspected thyroid problems," said Dr. William Harvey, a nuclear medicine physician and author of the study. "It also has very provocative scientific implications as we learn more about how statins affect different systems in the body."

The researchers re-examined 307 patients whose initial TSH blood tests, the most common measure of thyroid function, showed overactive thyroids. Symptoms of the condition, called hyperthyroidism, can include a fast heart rate and palpitations, tremors, anxiety, weak muscles, and difficulty sleeping.

For their study, the researchers administered more specialized diagnostics than the simple TSH tests. These new tests showed that the majority of patients on statins who appeared to be hyperthyroid by TSH tests actually had normal thyroid function. The tests also confirmed that the majority of patients not taking statins did indeed have thyroid problems, as the initial TSH tests suggested.

"These findings are fascinating because there’s a possibility that statins may improve thyroid function in patients with overactive thyroids," said Dr. Mark Feldman, chairman of internal medicine at Texas Health Dallas and the study’s senior author. "It could be an unexpected but delightful consequence of this research one day."

Hyperthyroidism affects about 4 million people in the United States. Graves’ disease is the most common form of the condition, which occurs when the body’s immune system mistakenly attacks the thyroid gland.

"This paper is important because it suggests that most people on statins for high cholesterol likely do not have any problem with their thyroid — even if they have low TSH test results (usually an indicator of an overactive thyroid)," said Dr. Patrick Barr, chief of nuclear medicine at Texas Health Dallas and co-author of the study. "That’s important because patients and their doctors might choose to not undergo a lot of expensive, invasive tests."

Statins have anti-inflammatory properties, which could affect other systems in the body, including the thyroid and other glands and organs, the researchers theorize