| Methods | 1. Generation of allocation sequence: Not cleary described 2. Allocation concealment: Patients were randomly assigned to receive either L‐T4 (as two 0.025 mg tablets), or two identical placebo tablets in a blinded manner. 3. Blinding: Double‐blinding 4. Sample size calculation: Not cleary described 5. Loss to follow‐up: None 6. Intention‐to‐treat analysis: Not cleary described 7. Similarity between groups: Yes | |
| Participants | 1. Inclusion criteria: Patients with TSH level greater than 4.0 mU/L in the presence of normal free thyroxine level (0.9 ‐ 1.9 ng/l). The etiology of SHT was Hashimoto's thyroiditis in patients (37/45). Only eight patients had been previously treated for hyperthyroidism (five by subtotal thyroidectomy, three with radioiodine). Euthyroidism was defined as a normal TSH level (0.4 ‐ 4.0 mU/L) with normal FT4. 2. Exclusion criteria: Neither the patients nor the members of the control group displayed signs of cardiovascular disease in their medical histories, physical examinations or electrocardiographies. Routine laboratory chemistry (plasma fasting glucose, blood urine nitrogen, creatinine, ALT, AST) was normal in all participants, and none were taking any medication. 3. Characteristics (Age (mean (SD)), gender, ethnicity, other): N=45, 38 female and 7 male, age 39.9 +/‐ 7.9. | |
| Interventions | 1. Intervention in experimental group (including number of patients, dosage, mode of administration, duration of treatment): L‐T4 (as two 0.025 mg tablets. A laboratory technician, who was in our study team, had access to the treatment code and the dose of L‐throxine was increased by 0.025 mg if the TSH level was still greater than 4.0 mcg/ml. This process continued until euthyroidism was achieved, with a mean dose of 0.064 mg daily. 2. Intervention in control group 1 (including number of patients, dosage, mode of administration, duration of treatment): Patients taking two identical placebo tablets in a blinded manner; some were given additional placebo tablets to maintain the blindness of the study. | |
| Outcomes | 1. BSA‐ body surface area 2. BMI‐ body mass
index 3. DBP‐ diastolic blood pressure 4.
SBP‐ systolic blood pressure 5. HR‐ hear rate
6. FT4 7. TSH 8. Conventional and
doppler echocardiographic measurements: FS (fractional
shortening), EF (ejection fraction), ICT (isovolumic contraction time), PEP
(pre‐ejection period), ET (ejection time), CO (cardiac output),
PEP/ET ratio. IRT (isovolumic relaxation time), Amax (late
transmitral flow velocity), E/A ratio, Emax (early transmitral flow
velocity), EDT (deceleration time), IRT (isovolumic relaxation time),
IMT (index of myocardial performance) EDD (left
ventricular end‐diastolic diameter), ESD (left ventricular end
systolic diameter), IVST (interventricular septum thickness), PWT (posterior
wall thickness), LVMI (left ventricular mass index), ESV(left ventricular
end‐systolic volume), EDV (left ventricular end‐diastolic
volume), SVR(systemic vascular resistance), EDT(mitral wave deceleration
time), ETC (left ventricular ejection time), Duration of follow‐up: 6 months |
|
| Notes | 1.Setting: Thoracic and Cardiovascular Surgery Center, Department of Cardiology, Istanbul, Turkey 2. Funding source: None. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear risk | B ‐ Unclear |
BMI = body mass index; SCH = subclinical hypothyroidism