A T2S cross-reactive material (compound W) in hyperthyroid patients with trophoblastic disease

In a previous study we observed increased serum levels of a 3,3'-diiodothyronine sulfate (T2S)-like material (compound W) in women who received human chorionic gonadotropin (hCG) treatment. In the present study we assessed serum compound W values in 113 women (total serum sample: 190) with trophoblastic disease, in 7 normal nonpregnant women during the menstrual cycle and 7 women given hCG treatment in the course of in vitro fertilization. Fifty-three women with trophoblastic disease had serum free thyroxine (FT4) concentrations greater than 3.0 ng/dL with suppressed serum thyrotropin (TSH) levels; 61 had FT4 values less than 3.0 ng/dL with a mean TSH of 0.83 mU/L. Mean (+/- SE) compound W concentrations in the high FT4 group were significantly higher than in the low FT4 group (76 +/- 8.1 vs. 21 +/- 1.7 ng T2S equivalent, p < 0.001) There were significant correlations between serum hCG and compound W concentrations (r = 0.472, p < 0.001), serum FT4 and hCG (r = 0.503, p < 0.0001) and serum FT4 and compound W (r = 0.585, p < 0.0001). In nonpregnant women serum compound W levels increased from 7.5 +/- 8 ng/dL at the end of the menstrual period to 15 +/- 1.7 ng/dL 21 days after the last menstrual period. Finally, a single dose of hCG (10,000 USP units, intramuscularly) increased mean (+/- SE) serum compound W levels from 12.8 +/- 2.3 to 64 +/- 9.7 ng/dL and 54 +/- 12 ng/dL at 9 and 16 days, respectively. These results indicate that hCG and perhaps luteinizing hormone (LH) increase serum compound W concentrations in women. The mechanism and significance presently are unclear.