Thrombocytosis and Hyponatremia as Predictors of Complicated Acute Appendicitis: Predictors of Appendicitis.

Background: Multiple serologic markers have been studied to predict complicated acute appendicitis (CAA) (C-reactive protein and procalcitonin); these increase health care costs and are not always available in medical centers in Mexico. There is a need for low-cost serologic markers to predict CAA and guide the preoperative management of patients. Our objective was to analyze the predictive value of hyponatremia and thrombocytosis for complicated acute appendicitis.

Methods: We analyzed 274 patients with AA surgically treated and divided them into two groups: the CAA group and the uncomplicated AA group. We compared the serum values of sodium and platelet blood counts on presentation in the emergency room between the two groups and the proportion of patients with hyponatremia and/or thrombocytosis. Receiver operating characteristic analysis was performed for the two biochemical markers. Sensitivity, specificity, and positive and negative predictive values were calculated for complicated appendicitis in the presence of hyponatremia and thrombocytosis.

Results: We found 87 patients with CAA and 187 with uncomplicated acute appendicitis. Patients with CAA presented with lower serum sodium values and higher platelet counts than uncomplicated patients. Hyponatremia was found in 54.8% of complicated patients and 29.2% in the uncomplicated group. Thrombocytosis was present in 11.6% of the complicated group and 3.2% in uncomplicated patients. We found a specificity and positive predictive value of 100% for complicated appendicitis in patients with hyponatremia and thrombocytosis.

Conclusions: In patients with abdominal pain and suspected acute appendicitis, the presence of hyponatremia and thrombocytosis is a strong predictive tool for the complicated disease. This is the first study to analyze the association between thrombocytosis and complicated appendicitis.