Evaluation of Ketone Bodies in Blood during Vomiting Episodes for Diagnosing Cyclic Vomiting Syndrome: A Nested Case-Control Study

Abstract Cyclic vomiting syndrome (CVS) is a very common emergency pediatric condition but can be challenging to diagnose due to the need to ascertain a history of recurrent vomiting episodes. The present study aimed to evaluate the utility of the blood ketone (beta-hydroxybutyric acid) level in diagnosing CVS by investigating ketone bodies in pediatric patients presenting to the emergency department with vomiting symptoms. The study included 395 patients who underwent rapid beta-hydroxybutyric acid testing for vomiting episodes between August 24, 2021 and September 30, 2023. Of these, 21 (5.3%) were diagnosed with CVS while 374 (94.7%) were classified as non-CVS. Additionally, 21 patients with CVS were compared with 63 controls matched for age and fasting duration. The beta-hydroxybutyric acid level was higher (3.6 mmol/L vs. 1.7 mmol/L, P < 0.001) in the CVS group than in the control subjects. The diagnostic probability model for CVS based on age (≥ 8 years) and beta-hydroxybutyric acid level (≥ 2.9 mmol/L) in the present study demonstrated a specificity of 97.1%, sensitivity of 42.9%, and positive likelihood ratio of 14.3. Conclusion: The blood ketone level was higher in pediatric patients with CVS presenting to the emergency department with vomiting symptoms than in matched control subjects. Age and the blood ketone level may have the potential to aid the early diagnosis of cyclic vomiting syndrome.