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Nodular thyroid disease risk increased for adults with acromegaly

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February 26, 2019

Adults with acromegaly may be prone to developing nodular thyroid disease and advanced nodule growth, according to findings published in Pituitary.

“Acromegaly is a rare, multisystemic disease caused by growth hormone hypersecretion, and it may cause multiple comorbidities,” Sema Ciftci Dogansen, MD, of the division of endocrinology and metabolism in the department of internal medicine for the Istanbul Faculty of Medicine at Istanbul University in Turkey, and colleagues wrote. “Nodular thyroid disease is one of these comorbidities, which is as common as nearly 60%. Associated factors on nodule formation are highly variable, and the most common ones are the effects of GH and insulin-like growth factor I.”

Dogansen and colleagues recruited 138 adults with acromegaly (73 women) from the hospital of Istanbul University in Turkey for analysis. Participants were considered to have nodular thyroid disease if they had a growth of more than 5 mm. Of the original cohort, 95 presented with nodular thyroid disease (mean age, 44 years; 51 women). The researchers noted that participants with nodular thyroid disease were older (P = .05) and had higher IGF-I levels (P = .01) than those without the condition.

After 7 years of follow-up, 56 of the participants with nodular thyroid disease returned for re-evaluation. A participant was considered to have nodular shrinkage if there was at least a 20% decrease in nodule size. Stable nodular status was defined by a change of less than 20% while growth was considered an increase in size of more than 20%. In addition, the researchers confirmed active acromegaly with high IGF-I levels and a GH level of more than 1 ng/mL.

Twenty-five percent of participants had nodule growth, 30% had shrinkage and 45% were stable. Higher rates of active acromegaly (P < .001) and IGF-I levels (P = .03) were found in participants with nodular growth compared with those without. The researchers further observed that active acromegaly led to a 9.1-fold increase in nodule growth (OR = 9.01; 95% CI, 2.011-35.129) and that there was a 1.01 odds increase for every 1 U change in IGF-I levels (OR = 1.01; 95% CI, 1.001-1.019).

“While the increased frequency of [nodular thyroid disease] is well-known in patients with acromegaly, various mechanisms have been proposed for nodule formation,” the researchers wrote. “Most importantly, GH and IGF-I have mitogenic and anti-apoptotic effects, and IGF-I has been shown to potentiate TSH-induced thyroid cellular growth in vitro studies. It is also reported that the effects of IGF-I receptor located on thyroid follicular cells are also responsible in cell proliferation due to autocrine and paracrine effects of IGF-I.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures. 

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