Neutrophil phagocytic capacity is lower in patients with abnormal thyroid function in critical illness

Background: Thyroid function is affected by critical illness – termed as non-thyroidal illness – and usually presents with low serum TSH and FT3 levels but normal FT4 concentrations. Critically ill patients may also have impaired immune function that could contribute to increased susceptibility to acquired infections and mortality. Thyroid hormones influence neutrophil levels and function but the effect of nonthyroidal illness on neutrophil function in critically ill patients is unknown.