Predictors of cardiovascular risk in patients with hyperthyroidism before and after radioiodine therapy
Anna Brona, Andrzej Milewicz, Anna Bohdanowicz-Pawlak, Diana Jedrzejuk & Anna Arkowska
It is suggested that radioiodine therapy in hyperthyroidism can increase mortality because of cardiovascular diseases. To determine that fact we have evaluated how the levels of predictors of the cardiovascular risk in serum such as: glucose, insulin, total cholesterol and high-density cholesterol, low-density cholesterol and triglycerides as well as CRP, fibrinogen and D-dimers changed in hyperthyroidism cases before and 12 up to 16 and 24 up to 28 weeks after radioiodine therapy. We studied 20 patients (non- smoking women, age 5169 years) with hyperthyroidism, before and after treatment. The following parameters were measured and estimated in serum using the commercial methods: TSH, fT4 and fT3, insulin, glucose, HOMA-IR, lipid profile, CRP, fibrinogen and D-dimers.Thyroid function was in the normal range in 19 patients 12 up to 16 weeks after therapy. Statistical analysis showed no significant changes in serum glucose (94.25±14.07 vs 93.9±11.73 mg/dl), total cholesterol (203.45±50.56 vs 213.75±43.98 mg/dl) and HDL cholesterol (64.7±16.99 vs 65.5±13.85 mg/dl) before and 24 up to 28 months after therapy. In contrast LDL cholesterol (110.15±39.82 vs 124±40.96 mg/dl), triglycerides (111.35±54.9 vs 120.25±41.42 mg/dl) and CRP (3.25±2.9 vs 3.98±1.97 mg/l) levels in serum increased significantly (P < 0.05) 24 up to 28 months after radioiodine therapy. The insulin level increased 24 up to 28 months after treatment (6.44±2.5 vs 7.45±3.65 μIU/ml) accompanied by slight increase in HOMA-IR (1.52±0.67 vs 1.66±0.81 mM mU/l). Serum levels of D-dimers (632.85±606.62 vs 500.5±281.36 ng/ml) as well as fibrinogen (393±89.68 vs 355.8±86.17 mg/l) decreased significantly 24 up to 28 months after therapy.
Our results suggest that radioiodine treatment have role in changing carbohydrate metabolism as well as lipid profile. The results support the observation about negative influence of radioiodine on cardiovascular risk in patients with hyperthyroidism when insulin, LDL cholesterol, triglycerides and CRP serum levels are considered. However it reduced hypercoagulable state. Due to small number of patients and short time of observation the answer for the question about the influence of radioiodine therapy on cardiovascular risk factors require further studies.