Pseudohyponatremia Associated with Severe Hypertriglyceridemia

The determination of serum electrolyte concentrations is a fundamental aspect of clinical laboratory testing, often accomplished through potentiometric methodologies ion-selective electrodes (ISE). Pseudohyponatremia, characterized by falsely low serum sodium levels amidst normal osmolality, poses diagnostic challenges, particularly in cases of extreme hypertriglyceridemia and hyperproteinemia. Here, we present a case of a 30-year-old woman with Congenital generalized lipodystrophy, manifesting pseudohyponatremia secondary to profound hypertriglyceridemia. Despite initial suspicion of hypovolemic hyponatremia, intravenous saline failed to rectify the sodium levels, prompting further investigation. Serum lipid profile analysis revealed markedly elevated triglyceride levels, implicating pseudohyponatremia due to lipoproteinemia. Diagnosis was confirmed through serum osmolality measurements and direct sodium analysis. Subsequent plasmapheresis sessions effectively reduced triglyceride levels and normalized serum sodium concentrations. Analytical interferences, particularly lipemia, underscore the importance of vigilant pre-analytic assessment and appropriate method selection. Mitigation strategies, including direct ISE methodologies and lipid removal techniques, are discussed in light of their implications for accurate sodium measurement. This case underscores the necessity of considering pseudohyponatremia in hyperlipidemic patients, advocating for comprehensive lipid profile assessment in hyponatremia workups. Additionally, it highlights the need for laboratory vigilance in detecting and managing analytical interferences to ensure accurate clinical interpretations and prevent potential complications associated with erroneous electrolyte corrections.