Male sex, low free T4 risk factors for liver dysfunction with radioactive iodine therapy
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Among adults who undergo radioactive iodine therapy for differentiated thyroid cancer, risk for hepatic dysfunction is elevated for men and all with low free thyroxine or high triglycerides, according to study data.
“The classic method of preparation for radioactive iodine therapy is thyroid hormone withdrawal,” Renfei Wang, MD, PhD, of the department of nuclear medicine at Tianjin Medical University General Hospital in China, and colleagues wrote in a study published in BMJ Open. “However, the application of thyroid hormone withdrawal usually results in some physical or psychological side effects associated with hypothyroidism, such as general oedema, constipation and depression. Evidence indicates that hypothyroidism may affect liver function or structure directly. Therefore, the identification of factors that may cause hepatic dysfunction is rather crucial.”
Researchers conducted a retrospective study of 996 adults who underwent radioactive iodine therapy following a complete or partial thyroidectomy at Tianjin Medical University General Hospital from January 2012 to March 2018 (68.5% women; mean age, 45.07 years). Demographics, surgery details, the presences of metastases, free triiodothyronine, free T4, thyroid-stimulating hormone, thyroglobulin, antithyroglobulin antibodies, total cholesterol and triglyceride levels were recorded during radioactive iodine therapy. Liver function test results were used to identify hepatic dysfunction. Follow-up was conducted monthly up to 4 months after surgery.
Of the study cohort, 31.6% had hepatic dysfunction, with most showing no clinical symptoms aside from abnormal liver function tests. The most common abnormal liver function was elevated alanine aminotransferase or aspartate aminotransferase, observed in 47.5% of cases. Of those with hepatic dysfunction, 80% were defined as mild and 20% as moderate.
In univariate analysis, men, thyroid hormone withdrawal time of longer than 21 days, free T3 less than 2.01 pmol/L, free T4 less than 4.78 pmol/L, TSH greater than 78.195 µIU/mL, total cholesterol higher than 5.17 mmol/L and triglycerides higher than 1.71 mmol/L were associated with an increased likelihood for hepatic dysfunction. In forward stepwise regression analysis, male sex, free T4 less than 3.8 pmol/L and triglycerides of 1.28 mmol/L or higher remained independent risk factors for predicting hepatic dysfunction.
The remission rate after 1 month of radioactive iodine therapy was 86.34%. Of those with mild hepatic dysfunction, about 90% had normal liver function tests at 1 month. The remission rate for those with moderate hepatic dysfunction was 71.43%.
Among adults with mild hepatic dysfunction, those receiving hepatoprotective treatment did not have a difference in remission rate compared with those not given treatment. Of 63 participants with moderate hepatic dysfunction receiving hepatoprotective treatment, 35 had remission 1 month after radioactive iodine therapy, 23 had remission at 2 months and five at 3 months. The average time for liver function to return to normal levels with moderate hepatic dysfunction was 1.8 months.
There were 189 participants with elevated triglycerides and hepatic dysfunction prior to undergoing radioactive iodine therapy. In subgroup analysis, 48 adults continued to have elevated triglycerides 1 month after radioactive iodine therapy. Twenty-five of those 48 were treated with lipid-lowering therapy. The remission rate of those who underwent lipid-lowering therapy was 84%, whereas those who were not given lipid-lowering therapy had a 65.21% remission rate.
“Lipid-lowering therapy is particularly important for patients with differentiated thyroid cancer with hepatic dysfunction before radioactive iodine therapy,” the researchers wrote. “For patients with differentiated thyroid cancer with hepatic dysfunction combined with dyslipidemia, lipid-lowering therapy is recommended, which is expected to shorten the remission time of hepatic dysfunction.”
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