Elevated thyroid stimulating hormone is associated with elevated cortisol in healthy young men and women

Abstract

BackgroundRecent attention has been given to subclinical hypothyroidism, defined as an elevation of TSH (4.5-10 uIU/L) with T4 and T3 levels still within the normal range. Controversy exists about the proper lower limit of TSH that defines patients in the subclinical hypothyroidism range and about if/when subclinical hypothyroidism should be treated. Additional data are needed to examine the relationship between markers of thyroid function in the subclinical hypothyroidism range, biomarkers of health and ultimately health outcomes.ObjectiveWe aimed to assess the relationship between serum TSH levels in the 0.5-10 uIU/L range and serum cortisol in a cohort of healthy young men and women without clinical evidence of hypothyroidism. Based on data in frank hypothyroidism, we hypothesized that serum TSH levels would be positively correlated with serum cortisol levels, suggesting derangement of the cortisol axis even in subclinical hypothyroidism.MethodsWe conducted a cross sectional study in 54 healthy, young (mean 20.98 +/− 0.37 yrs) men (19) and women (35). Lab sessions took place at 1300 hrs where blood was drawn via indwelling catheter for later assessment of basal serum TSH, free T3, free T4, and cortisol levels.ResultsAll but 1 participant had free T3 levels within the normal reference intervals; free T4 levels for all participants were within the normal reference intervals. Linear regression modeling revealed that TSH levels in the 0.5-10 uIU/L were significantly and positively correlated with cortisol levels. This positive TSH-cortisol relationship was maintained below the accepted 4.5 uIU/L subclinical hypothyroid cutoff. Separate regression analyses conducted by systematically dropping the TSH cutoff by 0.50 uIU/L revealed that the TSH-cortisol relationship was maintained for TSH levels (uIU/L) ≤4.0, ≤3.5, ≤3.0, and ≤2.5 but not ≤2.0. Linear regression modeling did not reveal a relationship between free T3 or free T4 levels and cortisol levels.ConclusionsResults suggest a positive relationship between TSH and cortisol in apparently healthy young individuals. In as much as this relationship may herald a pathologic disorder, these preliminary results suggest that TSH levels > 2.0 uIU/L may be abnormal. Future research should address this hypothesis further, for instance through an intervention study.

Thyroid disorders in obese patients. Does insulin resistance make a difference?

“…No correlation was found between cortisol and FT4 levels, which is consistent with previously reported data in the specialized literature (30).…”

A Case Control Study of Serum Lipid Level Alterations in Subclinical Hypothyroid Patients

“…Thyroid hormone analysis in the present case-control study revealed significantly higher mean TSH level of the SCH group as compared to the euthyroid group, in contrast to the results of the comparison of free T3 and T4 levels, between the groups. In addition, the free T3 and T4 levels between the groups in the present study were similar, consistent and within the normal range, similar to the observation by Walter et al (13) . In the present study, the mean values of serum cholesterol, triglycerides and apolipoprotein A was significantly high in the SCH group.…”

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“…Elevated levels of cortisol due to stress have observed to interfere with thyroid function in fish Walpita et al (2007). Chronic elevation in cortisol negatively feeds back the hypothalamus-pituitary-interrenal axis thus decreasing the peripheral circulating levels of T4 and T3 (Walter et al, 2012). Furthermore, prolonged cortisol elevations, caused by chronic stress, decrease the liver's ability to clear excess estrogens from the blood (Santin and Furlanetto, 2011).…”

“…In Amur sturgeon (Acipenser schrenckii), serum concentrations of total triiodothyronine (T3), free T4, and free T3 have been found inversely related to higher stocking densities, whereas serum total T4 level remained stable Li et al (2012). Crowding stress-induced elevation in levels of cortisol while suppression in profile of T4 might be due to negative feedback mechanism of elevated cortisol level on hypothalamus-pituitary-interrenal axis thus decreasing (Walter et al, 2012). Insufficient levels of circulating T4 levels and their carrier proteins (Fazio, Faggio, Piccione, Bonfiglio, & Marino, 2014) may cause the suppression of fish growth as observed in brook charr (Salvelinus fontinalis) (Vijayan, Ballantyne, & Leatherland, 1988).…”