Thyroid function in seasonal affective disorder

Lingjaerde, O; Reichborn‐Kjennerud, Ted; Haug, Egil

doi:10.1016/0165-0327(94)00071-g

Cited by 9 publications

(1 citation statement)

References 17 publications

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“…A number of small studies have attempted to investigate a possible link between SAD and thyroid function but have not conclusively established a statistically significant correlation. 58,59 However, an intervention trial did demonstrate that individuals suffering from SAD undergoing light therapy for 1 week had reduced TSH levels as well as significant reduction in depressive symptoms. 60 Those individuals with the most significant response in depression scoring to light therapy also had the largest decreases in TSH during treatment.…”

Section: Seasonal Changesmentioning

confidence: 99%

Extra-Thyroidal Factors Impacting Thyroid Hormone Homeostasis: A Review

McGregor¹

2015

j restorat med

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Peripheral metabolism plays a significant role in maintaining thyroid hormone expression in local tissues. The thyroid secretes thyroxine (T4) at substantially greater levels than triiodothyronine (T3), relying on peripheral mechanisms to convert T4 to T3. Peripheral control is exerted through a number of pathways. These pathways include deiodination, facilitated by deiodinase enzymes, as well as conjugation and lipid peroxidation. Factors influencing any or all of the peripherally active pathways continue to be explored and may help explain why many patients continue to experience symptoms consistent with hypothyroidism, including low body temperature, even when their thyroid blood tests are normal. These factors include liver and kidney function as well as seasonal changes. Although nonthyroidal illness syndrome was originally defined as a condition occurring without direct thyroid function impact, there is evidence that the thyroid itself may alter T3 and T4 during illness via modified gene regulation in the presence of proinflammatory cytokines. There are also a number of lifestyle behaviors, including fasting, alcohol dependence, and smoking that have been shown to affect peripheral metabolism of thyroid hormones. Zinc affects both the synthesis and mode of action of action of thyroid hormones. For example, thyroid transcription factors, which are essential for modulation of gene expression, contain zinc at cysteine residues. Selenium is required for the selenocysteine moieties that confer the function of the deiodinase enzymes. Selenium supplementation has been shown to reduce anti-thyroid peroxidase antibodies and anti-thyroglobulin antibodies in patients with autoimmune thyroiditis. Selenium has been shown to increase the level of glutathione peroxidase, which contains selenocysteine. Both Withania somnifera and Commiphora mukul have been shown to improve hypothyroidism by elevating T3 levels and increasing T3:T4 ratios through peripheral metabolic pathways.

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Section: Seasonal Changesmentioning

confidence: 99%