P1818 - Pseudo Hyponatremia Secondary to Obstructive Jaundice Delaying Management

Muhammad Bilal, MD¹, Rida Fatima, MD¹, Azhar Hussain, MBBS², Saurav Kini, MD³, Samhitha Bitla, MD⁴, Carmine Catalano, MD^1
1Bassett Medical Center, Cooperstown, NY; ²SUNY Upstate Medical University, Syracuse, NY; ³Tufts Medical Center, Boston, MA; ⁴Trinity Health Oakland / Wayne State University School of Medicine, Pontiac, MI

Introduction: Pseudohyponatremia, a form of iso-osmolar and isotonic hyponatremia, arises when severe hypertriglyceridemia or paraproteinemia significantly elevates the solid phase of plasma, impacting serum sodium results based on the measurement technology used. We represent a rare case of pseudo hyponatremia in obstructive jaundice delaying the management of pancreatic mass.

Case Description/Methods: A 67-year-old male with a past medical history of chronic hepatitis C and type 2 diabetes mellitus presented with weight loss and decreased appetite for the last two weeks. Labs were significant for elevated serum AST, ALT, ALP, total bilirubin, and severe hyponatremia (table 1). Serum and urine osmolality were 302 and 736, respectively. Urine sodium was 23 mEq/L. Blood glucose and alcohol level were normal. CT abdomen shows dilated intra- and extra-hepatic biliary ducts and a hypodense lesion in the pancreatic head. Endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic ultrasound-guided biopsy of the pancreatic mass was scheduled but was canceled due to concern about persistent hyponatremia for three consecutive days. The patient was put on fluid restriction of 1.2 L for 24 hours and given salt tablets with no significant difference in sodium levels. Due to concern about pseudo hyponatremia due to cholestasis, a lipid panel was checked (table 1). The sodium level with the direct ion-selective electrode (ISE) method was 132. The patient underwent ERCP and EUS with the placement of a CBD stent and biopsy of the pancreatic lesion. Repeat sodium levels, liver enzymes, and lipid panel were normal after one month (table 1).

Discussion: The formation of lipoprotein X, due to the entry of unesterified cholesterol and phospholipids into the bloodstream in patients with cholestasis, is the main cause of pseudo hyponatremia as it increases the solid component of plasma. The indirect ISE remains the widely used method for measuring serum electrolyte concentration in hospitals, assuming that plasma comprises 93% water and 7% proteins and lipids. The sample is analyzed without dilution with direct-ISE methods, such as those used in blood gas analyzers, and electrolytes are measured independently of serum plasma concentration. It is crucial to recognize pseudo hyponatremia secondary to obstructive jaundice and consider using the direct ISE method in such patients, as it may delay management, which usually involves addressing the underlying cause of the obstruction.


Disclosures:


Muhammad Bilal, MD¹, Rida Fatima, MD¹, Azhar Hussain, MBBS², Saurav Kini, MD³, Samhitha Bitla, MD⁴, Carmine Catalano, MD¹. P1818 - Pseudo Hyponatremia Secondary to Obstructive Jaundice Delaying Management, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.