DENVER – Undergoing percutaneous coronary intervention (PCI) may impair thyroid function and change the gland’s morphology, probably because of the cumulative effects of handling and exposure to radiation and iodine in the contrast dye, Samir Naim Assaad, MD, said during a poster presentation at the annual meeting of the American Thyroid Association.
Cardiologists should inform their patients of these possible effects as part of their pre- and post-PCI counseling so that they won’t be alarmed by the changes in how they feel, Dr. Assaad, chief of the division of endocrinology at Alexandria (Egypt) University, said in an interview.
Similarly, when a formerly euthyroid patient presents to an endocrinologist with sudden-onset hyperthyroidism, “Have you had a PCI recently?” should be one of the first questions asked. If the answer is yes, then further testing and imaging should be delayed at least 3 months, he noted.
Dr. Assaad and his associates examined 113 clinically euthyroid patients both before and several months after they underwent PCI for management of stable coronary artery disease. The cohort included 93 men, and patients’ ages ranged from 32 years to 73 years.
All the patients underwent a series of tests immediately before PCI, 24 hours after, and 3 months later. Those tests included serum free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), free T3/T4 ratio, antithyroperoxidase (anti-TPO), and high-sensitivity C-reactive protein.
The gland’s morphology, including volume, vascularity, nodules, and echogenicity, were assessed on the same timetable using ultrasonography.
One day after PCI, there was a significant increase in serum FT3 (5.2-0.5 vs. 3.3-0.7 pg/mL, P less than .001), and serum FT4 (1.3 – 0.5 vs 1.2 – 0.3 ng/dL, P = .04), with no significant change in serum TSH.
Three months after PCI, there was a further significant increase in serum FT4 (1.5 – 0.3 ng/dL), decrease in serum FT3 returning to baseline (3.2 – 1.3 pg/mL), and a significant increase in serum TSH, compared with just before PCI (mean, 3.2-5 vs. 1.5-2.1 mIU/L, P less than .001). Serum anti-TPO (AU/mL) showed a significant increase 3 months after PCI.
There was a significant increase in thyroid gland volume 3 months after PCI (13.6-3.9 vs. 13.1-3.5 cm3, P = .02). The measured echogenicity of the thyroid gland showed a significant decrease 3 months after PCI (67.1-10.9 vs. 88.7-25.6 GWE, P less than .001).
Thyroid radiation had a negative effect on serum TSH, anti-TPO, FT3, and FT3/FT4 ratio, and an inverse correlation of dye injection time with serum anti-TPO and TSH, judging from the findings of a regression analysis model.
Dr. Assaad was not included on the list of presenters with relevant financial disclosures that was provided by the American Thyroid Association.