Pseudohiponatremie

Pseudohiponatremie is a clinical laboratory phenomenon characterized by a falsely low serum sodium concentration that does not reflect a true hyponatremia. It is typically caused by laboratory interference or sample issues rather than an actual disturbance in the body's sodium balance. This condition is important to recognize to prevent unnecessary treatment based on misleading laboratory results.

The primary mechanisms leading to pseudohiponatremie involve interference in the measurement process, commonly due to hyperlipidemia, hyperproteinemia, or the presence of paraproteins. These substances can affect analytical methods such as indirect ion-selective electrodes (ISE), which are sensitive to sample turbidity or abnormal plasma composition. When the sample is lipemic or contains high levels of proteins, automated analyzers may inaccurately report low sodium levels, creating the illusion of hyponatremia.

Differential diagnosis of pseudohiponatremie includes genuine hyponatremia caused by conditions such as syndrome of inappropriate antidiuretic hormone secretion (SIADH), heart failure, or renal impairment. To confirm pseudohiponatremie, clinicians often re-analyze the serum using direct ion-selective electrode techniques, which are less susceptible to interference, or perform sample dilution and examination via manual methods.

Understanding pseudohiponatremie is crucial in clinical practice to avoid unnecessary interventions. Correct diagnosis relies on correlating laboratory data with clinical presentation and meticulous laboratory techniques. Recognizing this phenomenon helps prevent misdiagnosis and ensures appropriate management of patients with true hyponatremia or related disorders.