Alterations and diagnostic performance of capillary ketonemia in pediatric acute appendicitis: a pilot study

INTRODUCTION: The diagnostic performance of capillary ketonemia (CK) has been previously evaluated in context of pediatric acute gastroenteritis. To our knowledge, there is no literature on its performance in the setting of pediatric acute appendicitis (PAA). MATERIALS AND METHODS: In this study, 151 patients were prospectively included and divided into two groups: (1) patients with non-surgical abdominal pain in whom the diagnosis of PAA was excluded (n = 53) and (2) patients with a confirmed diagnosis of PAA (n = 98). In 80 patients (Group 1, n = 23 and group 2, n = 57) a CK was measured at the time of diagnosis. The PAA group was further classified into complicated (n = 18) and uncomplicated PAA (n = 39). Quantitative variables were compared between groups using the Mann–Whitney U test. Diagnostic performance of CK was evaluated with ROC curves. RESULTS: CK values were 0.3 [0.1–0.9] mmol/L in group 1 and 0.7 [0.4–1.4] mmol/L in group 2 (p = 0.01). Regarding the type of PAA, CK values were 0.6 [0.4–0.9] mmol/L in uncomplicated PAA and 1.2 [0.8–1.4] mmol/L in complicated PAA (p = 0.02). The AUC for the discrimination between groups 1 and 2 was 0.68 (95% IC 0.53–0.82) (p = 0.24) and the AUC for the discrimination between uncomplicated PAA and complicated PAA was 0.69 (95% IC 0.54–0.85) (p = 0.04). The best cut-off point (group 1 vs group 2) resulted in 0.4 mmol/L, with a sensitivity of 80.7% and a specificity of 52.2%. The best cut-off point (non-complicated vs complicated PAA) resulted in 1.1 mmol/L, with a sensitivity of 61.1% and a specificity of 76.9%. CONCLUSIONS: This study found significantly higher levels of CK in patients with PAA than in those with NSAP. Similarly, significantly higher levels were observed in patients with complicated than in those with uncomplicated PAA. Nevertheless, the diagnostic performance of CK was only moderate in the two settings analyzed. The potential usefulness of CK determination as a tool to guide the preoperative rehydration regimen of patients with PAA to prevent postoperative hyporexia and vomiting is a promising line of research and should be evaluated in future studies. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00383-022-05332-7.