Use of Serum Bicarbonate to Substitute for Venous pH in New-Onset Diabetes

Abstract

OBJECTIVE: To investigate whether serum bicarbonate (HCO3) levels can be used to accurately diagnose diabetic ketoacidosis (DKA) and classify its severity in children with new-onset diabetes mellitus (NODM). METHODS:Retrospective study of all patients with NODM presenting to Boston Children's Hospital from October 1, 2007, to July 1, 2013. DKA was defined as blood glucose $200 mg/dL, venous pH (vpH) ,7.3, and urine ketones $2+, and severe DKA as vpH ,7.1. Linear regression was used to assess serum HCO3 as a predictor of vpH, and logistic regression to evaluate serum HCO3 as a predictor of DKA and severe DKA.RESULTS: Of 690 study cohort subjects (47% girls, age 10.8 6 4.3 years, 76.7% white), 19.4% presented with DKA. The relationship between serum HCO3 and vpH was log-linear (r = 0.87, 95% CI 0.85-0.89, P , .001). HCO3 predicted vpH (R 2 0.75, P , .001) using the formula Diabetes mellitus in youth is common, with an estimated worldwide annual incidence of 80 000 children younger than 15 years 1 and the incidence is rising. 2 Diabetic ketoacidosis (DKA) at presentation of new-onset diabetes mellitus (NODM) occurs in approximately 15% to 70% of patients in Europe and North America. 3 The incidence of DKA at presentation is higher in younger children, ethnic minorities, families of lower socioeconomic status, and regions with a lower prevalence of diabetes, 3-7 which includes many resource-limited countries.In many pediatric academic medical centers in the United States, the standard initial diagnostic evaluation for children with NODM and especially those suspected to have DKA includes a panel of laboratory tests to measure venous blood gas (VBG) and the concentrations of plasma glucose, serum electrolytes, serum bicarbonate (HCO3), serum urea nitrogen (SUN), creatinine, hemoglobin A1c (HbA1c), and serum or urinary ketones. Acidemia is defined as arterial pH ,7.35 or venous pH (vpH) ,7.3, and traditionally, a vpH ,7.3 or a serum HCO3 ,15 mmol/L is used to confirm the diagnosis of DKA, with lower values of both indicating greater severity of the condition. Venous pH ,7.1 or serum HCO3 ,5 mmol/L has been used to define severe DKA. 3,8 These definitions are incorporated into hospital practice guidelines, and emergency department physicians and pediatricians often base management decisions, for example, admission to hospital and use of intravenous versus subcutaneous insulin therapy, on the vpH value. However, in remote or limited resource settings, VBG is not readily available.A recent study of pediatric patients seen in an emergency department suggested that the venous HCO3 concentration accurately predicts abnormal vpH in children with DKA. 9 Similarly, in adults, venous HCO3 concentrations predicted arterial pH with a high degree of sensitivity and specificity. 10 The objective of our study was to evaluate the ability of serum HCO3, measured at presentation, as part of a routine basic metabolic panel, to accurately predict DKA and classify its severity in a large population of youth with NODM. METHODS Stu...

Temporal trends in diabetic ketoacidosis at diagnosis of paediatric type 1 diabetes between 2006 and 2016: results from 13 countries in three continents

“…While venous pH and/or bicarbonate provide reliable data on the proportions of new cases presenting with DKA, this might not be possible in all settings and potentially raises cost implications. Serum bicarbonate can be a reliable substitute for venous pH in settings where access to venous pH measurement is limited [48]. A basic metabolic profile (including plasma glucose, venous pH or bicarbonate, blood urea nitrogen, serum creatinine and serum electrolytes) and, preferably, a blood ketone measurement (or, at least, a urine measurement) should be the standard of care for evaluating new-onset diabetes mellitus in a child.…”

ISPAD Clinical Practice Consensus Guidelines 2018: Diabetic ketoacidosis and the hyperglycemic hyperosmolar state

“…This can be caused by starvation (anorexia or religious fasting), a low carbohydrate high fat diet, or the off‐label use of SGLT2‐inhibitors . Serum bicarbonate concentration alone can substitute for vpH to diagnose DKA and classify severity in children with new onset diabetes mellitus and is suggested as an alternative to reliance on vpH in settings where access to vpH measurement is limited …”

“…[23][24][25] Serum bicarbonate concentration alone can substitute for vpH to diagnose DKA and classify severity in children with new onset diabetes mellitus and is suggested as an alternative to reliance on vpH in settings where access to vpH measurement is limited. 26 The frequency of type 2 diabetes mellitus (T2DM) in the pediatric age range is increasing. 27,28 The worldwide incidence and prevalence of type 2 diabetes in children and adolescents vary substantially among countries, age categories, and ethnic groups, which can be explained by variations in population characteristics and methodological dissimilarities between studies.…”

“…††Serum bicarbonate concentration alone can substitute for vpH to diagnose DKA and classify severity in children with new onset diabetes mellitus. It is suggested as an alternative to reliance on vpH, especially in settings in which access to vpH measurement is limited …”

ISPAD Clinical Practice Consensus Guidelines 2018: Limited Care Guidance Appendix

“…Subcutaneous regular insulin given every 4 hours has been shown to effectively and safely manage children with pH >7.0 . If blood gas testing is not available, serum bicarbonate concentration can be used in lieu of venous pH as an accurate predictor of the severity of DKA …”