LBODP029 Pseudohypobicarbonatemia In The Setting Of Diabetic Ketoacidosis And Severe Hypertriglyceridemia

Abstract

Abstract Background Severe hypertriglyceridemia is a rare complication of diabetic ketoacidosis (DKA); however, the resulting spuriously low measurements of serum bicarbonate ("pseudohypobicarbonatemia") are less well known. Clinical Case A healthy 15-year-old female presented to the emergency department with polydipsia, polyuria, and abdominal pain. She had a normal BMI and a sibling with type 1 diabetes (T1D). Labs demonstrated serum glucose of 351 mg/dL, serum ketones of 3.4 mmol/L, serum bicarbonate of <5 mmol/L, anion gap of >23 mmol/L, and triglycerides of >21,000 mg/dL. Serum lipase was normal at 70 units/L. She was admitted for protocolized DKA treatment with intravenous fluids and regular insulin drip. Hospital day 2, serum bicarbonate remained very low (7 mmol/L) despite declining ketones (1.9 mmol/L), decreasing anion gap (15 mmol/L), normal chloride (112 mEq/L), and normal lactic acid (1.3 mmol/L). A spurious lab was suspected, so bicarbonate was calculated from a venous blood gas (VBG) which showed a pH of 7.28 and a bicarbonate of 16.2 mmol/L at a time when serum bicarbonate was 7 mmol/L. Serial BMPs and VBGs were trended, with the serum bicarbonate consistently 7-10 mmol/L lower than the blood gas bicarbonate. Her ketoacidosis resolved, yet she remained hospitalized for continued IV regular insulin drip (max 0.3 units/kg/h) for treatment of severe hypertriglyceridemia. On hospital day 7, triglycerides fell below 500mg/dL. She never developed pancreatitis. She was discharged home on multiple daily injection insulin and a low-fat diet. Her triglyceride level two weeks later was 173 mg/dL. Diabetes autoantibodies returned positive, confirming a diagnosis of T1D. Clinical Lessons This case demonstrates that very high triglycerides can occur with pediatric DKA and cause a falsely low serum bicarbonate level, also known as "pseudohypobicarbonatemia". This is due to chemistry panel analyzers using absorbance to estimate bicarbonate levels, which makes them susceptible to triglyceride interference. In contrast, blood gas analyzers use the Henderson-Hasselbalch equation to calculate bicarbonate, thus, are not vulnerable to the same triglyceride interference. This is especially relevant in pediatrics, as triglyceride levels may not be routinely checked for patients in DKA, so massive elevation may be missed. It is also pertinent for centers where serum bicarbonate levels may be trended to monitor for DKA resolution, instead of blood gases. If the serum bicarbonate level remains low in a patient with DKA and resolving ketosis, a blood gas may be obtained as another way of looking at the acid/base status. If there is a discrepancy between the two measurements, triglycerides should be assessed, as this could change management and prevent complications such as pancreatitis. Presentation: No date and time listed