Table 2 Co-factors between cohorts of success and failure of first RAI therapy for hyperthyroidism
Variable | Success (n = 295) | Failure (n = 21) | P value |
|---|---|---|---|
Age (y) at time of diagnosis | 41.9 | 45.5 | NS (P = 0.32) |
Gender (F:M) | 226:69 | 12:9 | (P = 0.046) |
No prior treatment | 176 (59.7%) | 3 (14.2%) | (P < 0.001) |
Prior antithyroid medication | 114 (38.6%) | 17 (80.9%) | (P < 0.001) |
Methimazole | n = 35 | n = 2 | (P < 0.001) |
Propylthiouracil | n = 79 | n = 15 | (P < 0.001) |
Interval from diagnosis to treatment (d) | 329.6 | 289.6 | (P = 0.024) |
Size of thyroid gland (grams) | 49.3 | 62.1 | (P = 0.0017) |
24-h RAIU uptake | 0.56 | 0.62 | NS (P = 0.235) |
Dose of RAI 131I administered (mCi) | 18.1 | 19.9 | NS (P = 0.193) |
Dosing factor (mCi per gram) | 0.21 | 0.19 | NS (P = 0.259) |
Weight (lbs) | 150.1 | 136.8 | NS (P = 0.050) |
Thyrotropin (TSH) (normal 0.3–5.5 mIU/L) | 0.13 | 0.010 | NS (P = 0.948) |
Total tri-iodothyronine (TT3) (normal 95–170 pg/mL) | 328 | 415 | NS (P = 0.139) |
Free thyroxine (FT4) (normal 0.73–1.79 ng/dL) | 3.2 | 3.8 | (P = 0.026) |
Race: caucasian | 212 (71.8%) | 11 (52.5%) | NS (P = 0.195) |