Subclinical Hypothyroidism is Associated With Neuroendocrine Stress-Axis Dysregulation
Open Access
- Author:
- Connor, Chloe
- Area of Honors:
- Biobehavioral Health
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Laura Cousino Klein, Thesis Supervisor
Marie P Cross, Thesis Honors Advisor - Keywords:
- Thyroid
subclinical hypothyroidism
hypothyroidism
stress
HPA axis
HPT axis
biomarker
blood pressure
cortisol
thyroid stimulating hormone
TSH
t4
t3
depression
anxiety
Trier Social Stress Task - Abstract:
- Subclinical hypothyroidism, defined as normal T4 concentration with elevated thyroid-stimulating hormone concentration (TSH), affects up to 10 percent of the adult population. The diagnosis of subclinical hypothyroidism is based on statistically defined reference ranges and does not consider whether patients are at risk to develop overt disease. Our goal was to determine which poor health markers, if any, were associated with elevated TSH, and if this elevation is associated with pathophysiology of the HPA and HPT stress axes at elevation as minor as 2.0 mIU/L. To study this, we administered the Trier Social Stress Task and placed participants into a euthyroid group (TSH levels under 2.0 mIU/L) and a subclinical hypothyroidism group (TSH levels 2.0 mIU/L- 9.9 mIU/L). We found that TSH levels significantly predicted baseline depression scores [b = +0.50, t(45)= 3.84, p<0.001], predicted baseline anxiety scores [b = +0.34, t(48)= 2.49, p<0.05], predicted baseline perceived stress scores [b = +0.28, t(48)= 2.03, p<0.05], but did not predict fatigue or difficulty concentrating among participants. Participants with subclinical hypothyroidism displayed significantly higher systolic blood pressure levels than their euthyroid counterparts [F(1,49)=9.56, p<0.05]. However, these two groups did not differ in baseline DBP and HR. Separate one-way ANOVAs revealed that baseline cortisol and BMI were higher among participants with subclinical hypothyroidism [F(1,49)=13.22, p<0.001 and F(1,49)=5.77, p<0.05, respectively] Salivary cortisol decreased significantly between baseline and stress among participants in the subclinical hypothyroid group, but not among euthyroid individuals [timeXgroup effect: F(1,47)=4.64, p<0.05]. These results indicate that elevated TSH levels (2.0 mIU/L- 9.9 mIU/L) are associated with some measures of biobehavioral health dysfunction.