SUMMARYObjectivesBlood ketone (beta-hydroxybutyrate) measurements are suggested instead of urine ketone (acetoacetate) measurements in the diagnosis of diabetic ketoacidosis. Urine ketone examination is difficult and time consuming, and may result in an incorrect interpretation. Studies performed in emergency departments on blood ketones are limited. Our objective is to compare urine ketones and capillary blood ketones in patients whose serum glucose levels were ≥150 mg/dl.MethodsIn our cross-sectional prospective study, finger-stick blood beta-hydroxybutyrate, arterial blood gas and urine ketone measurements of patients whose serum glucose levels were 150 mg/dL and higher were performed in the emergency department.ResultsA total of 265 patients were included in the study. The mean age of the patients was 62.4±14.9 years, and 65.7% of them were female. The mean of the capillary blood ketone levels of the patients was determined to be 0.524±0.9 mmol/L (min: 0 mmol/L, max: 6.7 mmol/L). In 29 (13.1%) of the 221 patients whose urine ketone levels were negative, the finger-stick blood ketone levels were positive. Three of these patients were severely ketonemic, six were moderately ketonemic, and 20 were mildly ketonemic.ConclusionsIn patients admitted to the emergency department with a blood glucose level of 150 mg/dL or higher, performing a capillary blood ketone measurement instead of a urine ketone measurement was a better predictor of ketonemia.