Clinical InvestigationFunctional Capacity and Muscular Abnormalities in Subclinical Hypothyroidism
Section snippets
Study Design
A cross-sectional case-control study was performed, in which the presence of neuromuscular symptoms, muscle strength, and functional capacity of patients with sHT were investigated and compared with healthy subjects without thyroid diseases.
Patients
Individuals with sHT, defined as having elevated serum TSH (> 4.0 μUI/mL) and normal FT4 levels (0.9–1.8 ng/dL), were recruited from the outpatient clinic of Clementino Fraga Filho University Hospital in Rio de Janeiro, Brazil. Forty-four patients aged between
RESULTS
General characteristics of patients and controls are presented in Table 1. A higher prevalence of smokers was observed in the control group, but this did not interfere in the analyses [Figure 1, Figure 2]. Mean serum FT4 levels were statistically lower in patients than in controls (1.06 ± 0.19 versus 1.21 ± 0.16; P < 0.05), although all were in the reference range. As expected, TSH levels were markedly higher in sHT (5.1 ± 3.3 versus 1.4 ± 0.7; P < 0.05) (Table 1).
Complaints of cramps (54.8% versus 25.0%; P
DISCUSSION
Only a few studies have been published about neuromuscular alterations in sHT. In the current study, patients had a greater frequency of neuromuscular complaints than controls. They also had greater frequency of reduced muscle strength as evaluated by MMT in sHT than in controls, and this correlated positively with neuromuscular complaints. In addition, patients with altered MMT had lower median values of IS and QS. The frequency of abnormal QS was not different when comparing sHT and controls
CONCLUSIONS
Functional capacity was not apparently affected by sHT in the studied population.
Neuromuscular complaints and altered MMT were significantly more frequent in patients with sHT. Despite no difference being observed for QS and IS, they tended to be lower in patients with altered MMT and in those with neuromuscular symptoms. We believe that these findings may suggest a mild incipient neuromyopathy that must be considered in the decision to begin levothyroxine treatment.
Finally, we believe that
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