Is TSH useful for allergy?

TSH (thyroid-stimulating hormone) is not a standard marker for allergy diagnosis. Allergy testing relies on specific IgE, skin prick tests, or provocation tests. However, some evidence suggests that thyroid dysfunction (e.g., Hashimoto's thyroiditis) may be associated with increased risk of allergic conditions such as chronic urticaria or atopic dermatitis, possibly via immune modulation by thyroid hormones and autoimmune mechanisms. The evidence is mostly mechanistic and based on observational studies, not RCTs. Therefore, TSH screening may be considered in unclear allergy cases but does not replace specific allergy diagnostics. From a personalized medicine perspective (e.g., MyBody-X), TSH alone is insufficient as an allergy biomarker. A comprehensive approach including IgE, eosinophils, and thyroid autoantibodies is recommended. Caveat: TSH levels fluctuate diurnally and can be affected by medications.