Role of hyponatremia in differentiating complicated appendicitis from uncomplicated appendicitis: a comparative study

Some studies suggest that serum sodium level may decrease at a greater degree in complicated acute appendicitis (CA) because of the increased severity of inflammation. This study aimed to determine the predictive value of some inflammatory markers and hyponatremia in differentiating CA from uncomplicated acute appendicitis (UCA).

In this retrospective cohort study, the data of patients who underwent urgent appendectomy in Department of General Surgery, Eskisehir Osmangazi University from January 01, 2016 to January 01, 2021, were analyzed. Patients were divided according to appendicitis type, UCA and CA.

In this study, 10.2% (n = 79) of 772 acute appendicitis cases were CA. Multiple logistic regression analysis revealed that high age (p = 0.001), male sex (p = 0.014), high leukocyte count (p = 0.045), low lymphocyte count (p = 0.023) and hyponatremia (p <0.001) were independently associated with CA. Patients with hyponatremia (sodium level ≤134 mEq/L) had 3.050-fold higher risk for CA than patients with normal sodium level (odds ratio: 3.050, 95% confidence interval: 1.668-5.576). The results of the ROC analysis performed to assess the role of sodium level in detecting CA showed a sensitivity of 27.8% and a specificity of 92.1% (cut-off: 133.5 meq/L) (p = 0.001; area under the curve: 0.612 [0.539-0.684]).

Clinicians should be aware of the higher likelihood of CA occurrence in patients with appendicitis in whom hyponatremia, leukocytosis, or lymphopenia is detected in the laboratory examination.