Okan ÖZGÖKÇE, Murat ALAY
Intercontinental Journal of Internal Medicine - 2026;4(3):60-64
Aims: Hyponatremia observed during the course of COVID-19 infection is closely associated with disease prognosis. The objective of this study is to determine the prevalence of syndrome of inappropriate antidiuretic hormone secretion (SIADH) in patients diagnosed with COVID-19 and to analyze the relationship between this condition and inflammatory markers and stress response parameters. Methods: The study included 50 patients hospitalized with a diagnosis of COVID-19 who were found to have hyponatremia (Na<135 mEq/L). The diagnosis of SIADH was based on the criteria of clinical euvolemia, low plasma osmolarity (<275 mOsm/kg), and high urinary sodium (>40 mEq/L). TSH and cortisol levels were evaluated to rule out secondary causes in the differential diagnosis. Patients were divided into two groups: SIADH-positive (n=37) and non-SIADH (n=13). The Mann-Whitney U test was used for intergroup comparisons, and the Spearman test was used for correlation analyses. Results: The mean age of the patients was 62.1+/-12.3 years, and a higher proportion of female patients was observed in the SIADH group (p=0.038). Serum sodium levels (median: 130.0 mEq/L) were significantly lower in the SIADH (+) group compared to the Non-SIADH group (p<0.01). Among inflammatory markers, ferritin levels were found to be significantly higher in the SIADH group (741.0 vs 335.0 ng/ml; p=0.029), and serum cortisol levels were also found to be markedly elevated in this group (7.5 vs 1.6 µg/dl; p=0.017). In the correlation analysis, a significant negative correlation was found between serum sodium levels and cortisol (r=-0.325, p=0.021) and ferritin (r=-0.284, p=0.046). Conclusion: The primary etiological factor for COVID-19-associated hyponatremia is SIADH. Elevated ferritin and cortisol levels accompanying this condition indicate that systemic inflammation and the stress response are associated with the severity of hyponatremia. Preserved urinary sodium and elevated cortisol levels are key clinical clues supporting the diagnosis of SIADH in the course of COVID-19.
