Is suppressed thyroid-stimulating hormone (TSH) associated with subclinical depression in the Danish General Suburban Population Study?
BACKGROUND
The first phase of the Danish General Suburban Population Study (GESUS) including 8214 individuals was an attempt to evaluate the association between subclinical hypothyroidism without or with elevated peroxidase antibodies and depression. No such association was found. In the second phase, including 14,787 individuals, we have focused on suppressed TSH (thyroid-stimulating hormone) and depression.


OBJECTIVE
To evaluate to what extent suppressed TSH is associated with subclinical depression.


METHODS
The total scores of the Major Depression Inventory (MDI) were used to evaluate subclinical depression, both by its total score and by an algorithm of the subthreshold depressed by presence of at least three of the 10 ICD-10 depression symptoms. Serum levels of TSH were used to classify the individuals into suppressed (TSH < 0.4 mIU/l), elevated (TSH ≥ 3.8 mIU/l) and normal reference (TSH between 0.4 and 3.7 mIU/l).


RESULTS
We identified 285 individuals with suppressed TSH and 1266 individuals with elevated TSH. The MDI total score was 7.55 in suppressed TSH individuals, 6.22 in elevated TSH individuals and 6.52 in normal reference individuals (P = 0.01). When the MDI was used diagnostically to identify subclinical depression, the prevalence was 8.07% in suppressed TSH individuals, 5.8% in normal reference individuals and 5.29% in elevated TSH individuals.


CONCLUSIONS
This population-based study supports that persons with suppressed TSH (subclinical hyperthyroidism) seem to have a risk, although small, of subclinical depression.
Jan Kvetny, Chief Physician, Department of Research, Naestved University Hospital, Copenhagen University Hospital , and Professor of Endocrinology, Faculty of Health and Medical Sciences, University of Southern Denmark , Denmark.
Jan
J
Kvetny
Christina
C
Ellervik
Per
P
Bech
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D003865:Major Depressive Disorder / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D013383:Suburban Population; D013972:Thyrotropin / Q000097:blood*
D015415:Biomarkers; D013972:Thyrotropin
MDI; Subclinical depression; suppressed TSH