Hyponatremia: A possible immuno-neuroendocrine interface with COVID-19 in a kidney transplant recipient

There is fast-emerging, cumulative clinical data on coronavirus disease 2019 (COVID-19) in kidney transplant recipients. Although respiratory tract symptoms are often the initial presentation among kidney transplant recipients who contract COVID-19, other clinical features which may indicate underlying SARS-CoV-2-related inflammation, such as gastrointestinal symptoms, are not uncommon. Hyponatremia can develop and may reflect underlying inflammation. Interferon-6 is an important pro-inflammatory cytokine involved in the pathogenesis of severe COVID-19 complications and may play a role in the inappropriately higher secretion of antidiuretic hormone leading to hyponatremia. This pathway is the so-called immuno-neuroendocrine interface. Hyponatremia in COVID-19 has been reported in a few case series of non-kidney transplant patients and only one reported kidney transplant recipient. However, the clinical course and prognostic value of hyponatremia in this population are not described in detail. We report a kidney transplant recipient who was infected with COVID-19 and exhibited severe hyponatremia secondary to the syndrome of inappropriate antidiuretic hormone secretion. Hyponatremia is one of the clinical presentations of COVID-19, although less common, and may occur more frequently in kidney transplant recipients. Thus, the possible underlying immuno-neuroendocrine relationship related to the inflammatory process of COVID-19 leading to hyponatremia and its prognostic value are reviewed.