Does Subclinical Hypothyroidism Add Any Symptoms? Evidence from a Danish Population-Based Study

Allan Carlé; Jesper Scott Karmisholt; Nils Knudsen; Hans Perrild; Bettina Heinsbæk Thuesen; Lars Ovesen; Lone Banke Rasmussen; Inge Bülow Pedersen

doi:10.1016/j.amjmed.2021.03.009

Does Subclinical Hypothyroidism Add Any Symptoms? Evidence from a Danish Population-Based Study

Am J Med. 2021 Sep;134(9):1115-1126.e1. doi: 10.1016/j.amjmed.2021.03.009. Epub 2021 Apr 16.

Authors

Allan Carlé¹, Jesper Scott Karmisholt², Nils Knudsen³, Hans Perrild³, Bettina Heinsbæk Thuesen⁴, Lars Ovesen⁵, Lone Banke Rasmussen³, Inge Bülow Pedersen²

Affiliations

¹ Department of Endocrinology, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Institute, Aalborg University, Denmark. Electronic address: carle@dadlnet.dk.
² Department of Endocrinology, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Institute, Aalborg University, Denmark.
³ Department of Endocrinology, Bispebjerg University Hospital, Copenhagen, Denmark.
⁴ Centre for Clinical Research and Prevention, Capital Region of Denmark, Copenhagen, Denmark.
⁵ Department of Internal Medicine, Slagelse Hospital, Slagelse, Denmark.

PMID: 33872585
DOI: 10.1016/j.amjmed.2021.03.009

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: Case-control study; Hypothyroidism; Overt hypothyroidism; Population-based study; Subclinical hypothyroidism; Symptoms.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Age Factors
Alcohol Drinking / epidemiology
Asymptomatic Diseases / epidemiology*
Body Mass Index
Case-Control Studies
Denmark / epidemiology
Educational Status
Female
Humans
Hypothyroidism* / blood
Hypothyroidism* / diagnosis
Hypothyroidism* / epidemiology
Hypothyroidism* / psychology
Male
Mental Health
Middle Aged
Smoking / epidemiology
Symptom Assessment* / methods
Symptom Assessment* / statistics & numerical data
Thyrotropin / analysis*
Thyroxine / therapeutic use*

Substances

Thyrotropin
Thyroxine