Thyroid Signaling Biomarkers in Female Symptomatic Hypothyroid Patients on Liothyronine versus Levothyroxine Monotherapy: A Randomized Crossover Trial
Table 1
Baseline characteristics.
Prior to randomization (n = 59)
Allocated to first LT4 and then LT3 (n = 27)
Allocated to first LT3 and then LT4 (n = 32)
P Value
Age at inclusion (years)
42.9 ± 9.7
42.8 ± 8.6
42.9 ± 10.7
0.991
Age at hypothyroidism diagnosis (years)
30.6 ± 10.2
29.8 ± 8.6
31.2 ± 11.4
0.590
Duration of substitution monotherapy LT4 (years)
10.6 ± 7.0
10.9 ± 7.3
10.3 ± 6.8
0.778
Type of therapy at inclusion
LT4 monotherapy
46 (78.0)
20 (74.1)
26 (81.3)
0.513
LT4/LT3 combination therapy
12 (20.3)
7 (25.9)
5 (15.5)
0.728
Thyroid extract
1 (1.7)
0 (0)
1 (3.1)
1.000
Etiology of hypothyroidism
Autoimmune/idiopathic
56 (94.9)
27 (100%)
29 (90.6)
0.299
Postsurgical
2 (3.4)
0 (0)
2 (6.3)
0.549
Radioiodine
1 (1.7)
0 (0)
1 (3.1)
1.000
Body mass index (kg/m2)
28.1 ± 5.6
28.5 ± 5.9
27.8 ± 5.5
0.624
Resting heart rate (beats/minute)
64.7 ± 11.2
67.4 ± 12.1
62.4 ± 9.9
0.084
Systolic blood pressure (mmHg)
118.0 ± 13.7
115.5 ± 13.2
120.2 ± 13.9
0.191
Diastolic blood pressure (mmHg)
78.3 ± 7.9
77.2 ± 8.7
79.4 ± 7.0
0.282
TSH (mU/L)
0.64 (0.26–1.60)
0.82 (0.28–1.50)
0.63 (0.25–1.9)
0.767
FT4 (pmol/L)
16.8 (14.7–19.0)
17.0 (14.2–20.0)
16.4 (14.8–18.0)
0.970
FT3 (pmol/L)
4.4 (3.8–4.9)
4.4 (3.8–4.8)
4.4 (3.8–5.0)
0.664
Positive TPO-ab1
31 (52.5)
17 (63.0)
14 (43.8)
0.226
Residual hypothyroid symptoms
Fatigue
57 (96.6)
26 (96.3)
31 (96.6)
1.000
Cold intolerance
54 (91,5)
26 (96.3)
28 (87.5)
0.460
Cognitive disturbances
48 (81.4)
24 (88.9)
24 (75.0)
0.303
Emotional disturbances
38 (64.4)
16 (59.3)
22 (68.8)
0.627
Data are presented as mean ± SD or number (%) or median (interquartile range: 25–75%) as appropriate. TSH: thyroid-stimulating hormone (ref. range 0.5–3.6), FT4: free thyroxine (8.0–21.0), FT3: free triiodothyronine (2.8–7.0), TPO-ab: thyroid peroxidase antibodies. 1 Cutoff value for positive TPO-ab was 35 kIU/l.
