Table 3.
Thyroid Hormone Levels of Participant Groups, by Serum TSH
| LT4-Treated (n = 469) | Matched Controls (n = 469) | |||
|---|---|---|---|---|
| TSH 0.24–1.74 (n = 213) | TSH 1.75–5.40 (n = 256) | TSH 0.24–1.74 (n = 210) | TSH 1.75–5.40 (n = 259) | |
| Age (y) | 64.1 ± 13.2 | 64.5 ± 14.8 | 64.0 ± 13.4 | 64.3 ± 14.35 |
| Female (%) | 178 (84) | 182 (71)b | 181 (83) | 195 (72)c |
| Race/ethnicity (%) | ||||
| Non-Hispanic white | 156 (73) | 180 (70) | 162 (74) | 186 (89) |
| Non-Hispanic black | 19 (9) | 17 (7) | 17 (8) | 21 (8) |
| Hispanic | 28 (13) | 48 (19) | 29 (13) | 51 (19) |
| Other | 10 (4) | 11 (4) | 9 (4) | 12 (4%) |
| Serum TSH (mIU/liter) | 0.95 ± 0.43 | 3.11 ± 0.97b | 0.98 ± 0.41 | 3.09 ± 0.95c |
| Serum free T3 (pg/ml) | 2.88 ± 0.34 | 2.83 ± 0.33 | 3.05 ± 0.40 | 2.98 ± 0.38 |
| Serum total T3 (ng/ml) | 98.04 ± 21.26 | 97.15 ± 20.14 | 111.96 ± 28.38 | 105.32 ± 21.25c |
| Serum free T4 (ng/ml) | 0.99 ± 0.21 | 0.90 ± 0.20b | 0.83 ± 0.14 | 0.78 ± 0.14c |
| Serum total T4 (μg/dl) | 9.52 ± 1.80 | 8.84 ± 1.67b | 8.29 ± 1.48 | 7.92 ± 1.60c |
| Free T3:free T4c | 3.03 ± 0.75 | 3.31 ± 0.81b | 3.76 ± 0.75 | 3.91 ± 0.75c |
| Total T3:free T4c | 104.07 ± 35.09 | 114.19 ± 36.71b | 138.47 ± 41.09 | 138.45 ± 36.33 |
| Total T3:total T4c | 10.60 ± 2.63 | 11.34 ± 2.99b | 13.80 ± 3.85 | 13.61 ± 2.93 |
The mean serum TSH level from the entire population was 1.75 mIU/liter. Participants within each group were then classified as having serum TSH levels above or below this mean, and then thyroid function tests reassessed for each subgroup. Data are mean ± sd, n (%). P value by χ3 (categorical data) or Student’s t test (continuous data).
a
For the comparison of LT4-treated and matched controls.
b
Multiplied × 1000.