Purpose: To examine the association between peak systolic velocity (PSV) in superior thyroid arteries (STA) and free ß-human chorionic gonadotrophin (free ß-hCG) in pregnant women with normal and suppressed level of thyroid stimulating hormone (TSH) and to determinate the role of thyroid ultrasound in differentiating the cause of hyperthyroidism in the first trimester of pregnancy.
Material & Methods: Color flow Doppler sonography (SFDS) with determination peak systolic velocity in STA were investigated in 44 pregnant women at 11-13 weeks of gestation (20 with elevated level serum free ß-hCG and normal serum TSH, 10 with gestational thyrotoxicosis (GT), who had elevated serum ß-hCG and suppressed serum TSH, 5 with Graves’ disease and 10 healthy euthyroid pregnant women with normal level serum free ß-hCG).
Results: The STA peak systolic velocity in patients with GT (41 [39- 43] cm/s) was significantly higher (p<0,05) than those in euthyroid patients with elevated level serum free ß-hCG (35[33-40] cm/s) and in euthyroid pregnant women with normal level serum free ß-hCG (30[25- 32] cm/s). But STA-PSV in pregnant women with Graves’ disease (87 [78-96] cm/s) was significantly higher than those in pregnant with GT (p< 0,001). There was significant association between free ß-hCG and PSV in STA in euthyroid patients with elevated level serum free ß-hCG (r= 0,68, p< 0,001) as well as euthyroid pregnant women with normal level serum free ß-hCG (r=0,64,p<0,05), but not in those with GT (r=0,15, p =0,69).There was not significant association between TSH and STA-PSV in all of patients’ groups (p>0,05)
Conclusions: CFDS with determination of STA-PSV is useful to differentiate Graves’ disease and GT at 11-13 weeks of gestation. Free ß-hCG has a weak thyrotrophic property and cannot be considered as a sole factor in the etiology of GT.
