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Abstract: FR-PO629

Spurious Low Serum Bicarbonate Level due to Severe Hypertriglyceridemia: A Clinical Challenge

Session Information

Category: Fluid and Electrolytes

  • 902 Fluid and Electrolytes: Clinical

Authors

  • Dana, Ali Pardis, Vista Del Mar Medical Group, Inc, Oxnard, California, United States
  • Kazory, Amir, University of Florida, Gainesville, Florida, United States
Introduction

A low serum bicarbonate level (SBL) in the presence of a high anion gap (AG) generally indicates presence of metabolic acidosis secondary to an increase in unmeasured anions. Herein, we report 2 patients with profound hypertriglyceridemia (HTG) who presented with low measured SBL and a high AG. Evaluation revealed that the low SBL was spurious and resulted from extremely high serum triglyceride (TG) levels; once HTG was treated, the reported SBL was corrected.

Case Description

The first patient is a 48-year old man with a history of chronic pancreatitis secondary to severe HTG. He was admitted for acute pancreatitis and was found to have a serum TG of 3267 mg/dl. He had normal renal function and electrolytes but SBL was reported <5 mmol/l on chemistry panel with an AG of >28. However, arterial blood gas (ABG) revealed absence of acidemia with PH 7.4, PCO2 35, PO2 84, and bicarbonate 23 suggesting presence of spurious low SBL. Therapeutic plasma exchange (TPE) resulted in rapid improvement of HTG to 731 mg/dl the next day; SBL rose simultaneously to 18 mmol/l confirming the diagnosis.
The second patient is a 26-year old woman with a history of diabetes who was admitted for acute pancreatitis. She was found to have a serum TG level of 10,950 mg/dl. SBL on routine chemistry panel was reported 9 mmol/l with an AG of 27. ABG showed pH 7.4, PCO2 37, PO2 75 and bicarbonate 23.7. She underwent 3 sessions of TPE, which lowered her serum TG to 1420 mg/dl and raised measured SBL to 18 mmol/l within 3 days with no additional intervention.

Discussion

Accurate assessment of bicarbonate is essential for the diagnosis of acid-base disturbances. Bicarbonate can be “measured” in serum as total carbon dioxide (tCO2) or “calculated” from ABG analysis (Henderson-Hasselbalch equation). In most instances, tCO2 and bicarbonate are closely related due to the constancy of the apparent dissociation constant of blood carbonic acid (pK’). Presence of a marked difference between the two values creates a clinical challenge that should prompt identification of a cause. Severe HTG interferes with laboratory testing in several ways (e.g. turbidity) and should be considered in the settings where there is no clinically apparent reason for low SBL. These 2 cases highlight the need for the clinicians to keep severe HTG in the differential diagnosis of SBL to avoid management errors.