Abstract
Background
Few studies have scrutinized the spectrum of symptoms in subclinical hypothyroidism.
Methods
From 3 Danish Investigation on Iodine Intake and Thyroid Diseases (DanThyr) cross-sectional
surveys performed in the period 1997 to 2005, a total of 8903 subjects participated
in a comprehensive investigation including blood samples and questionnaires on previous
diseases, smoking habits, alcohol intake, and education. From the 3 surveys we included
patients with subclinical hypothyroidism (n = 376) and euthyroid controls (n = 7619).
We explored to what extent patients with subclinical hypothyroidism reported 13 previously
identified hypothyroidism-associated symptoms (tiredness, dry skin, mood lability,
constipation, palpitations, restlessness, shortness of breath, wheezing, globus sensation,
difficulty swallowing, hair loss, dizziness/vertigo, and anterior neck pain). In various
uni- and multivariate regression models we searched for circumstances predicting why
some patients have more complaints than others.
Results
Subclinically hypothyroid patients did not report higher hypothyroidism score [(median,
interquartile range), 2 (0-4) vs 2 (0-4), P = .25] compared with euthyroid controls. Within the group of subclinical hypothyroid
patients, comorbidity had the highest impact on symptoms (tiredness, shortness of
breath, wheezing; all P < .001); TSH level had no impact on symptom score; and younger age was accompanied
by higher mental burden (tiredness, P < .001; mood lability, P < .001; restlessness, P = .012), whereas shortness of breath was associated with high body mass index (P < .001) and smoking (P = .007).
Conclusion
Patients with a thyroid function test suggesting subclinical hypothyroidism do not
experience thyroid disease-related symptoms more often than euthyroid subjects. In
subclinical hypothyroidism, clinicians should focus on concomitant diseases rather
than expecting symptomatic relief following levothyroxine substitution.
Keywords
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Article info
Publication history
Published online: April 15, 2021
Footnotes
Funding: The present study is based on previous cross-sectional studies (C1+C2) and a register study of hypothyroid patients. Funding has been acknowledged in several papers. For the present study we were supported by the Beckett Foundation.
Conflicts of Interest: The authors declare no conflicts of interest that may be perceived as prejudicing the impartiality of the research reported.
Authorship: All authors had access to the data, and participated in analyzing data and writing and revising the manuscript.
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