Imagine you’re driving a car and suddenly your dashboard lights up, warning you that your gas tank is running dangerously low. Just like that, scientists have discovered a marker in the blood that can serve as an early warning sign for respiratory failure in patients with amyotrophic lateral sclerosis (ALS). In this study, researchers looked at the levels of serum chloride, a simple and inexpensive blood test, in ALS patients at the time of diagnosis. They found that higher serum chloride levels were associated with a greater risk of impending respiratory decompensation. By identifying this marker early on, doctors can intervene with non-invasive ventilation and improve patient outcomes. The researchers also noted correlations between serum chloride and other clinical features, such as forced vital capacity and weight loss. This study highlights the potential of using a readily available biomarker to stratify ALS patients into different prognostic categories. So next time you’re giving your car a check-up, don’t forget to give your blood a check too! Dive into the research to learn more about this exciting discovery.

Respiratory failure is the most common cause of death in patients with amyotrophic lateral sclerosis (ALS) and occurs with great variability among patients according to different phenotypic features. Early predictors of respiratory failure in ALS are important to start non-invasive ventilation (NIV). Venous serum chloride values correlate with carbonate (HCO3-) blood levels and reflect metabolic compensation of respiratory acidosis. Despite its wide availability and low cost, few data on serum chloride as a prognostic marker exist in ALS literature. In the present study, we evaluated serum chloride values at diagnosis as prognostic biomarkers for overall survival and NIV adaptation in a retrospective center-based cohort of ALS patients. We collected all ALS patients with serum chloride assessment at diagnosis, identified through the Piemonte and Valle d’Aosta Register for ALS, evaluating the correlations among serum chloride, clinical features, and other serum biomarkers. Thereafter, time-to-event analysis was modeled to predict overall survival and NIV start. We found a significant correlation between serum chloride and inflammatory status markers, serum sodium, forced vital capacity (FVC), ALS functional rating scale-revised (ALSFRS-R) item 10 and 11, age at diagnosis, and weight loss. Time-to-event analysis confirmed both in univariate analysis and after multiple confounders’ adjustment that serum chloride value at diagnosis significantly influenced survival and time to NIV start. According to our analysis, based on a large ALS cohort, we found that serum chloride analyzed at diagnosis is a low-cost marker of impending respiratory decompensation. In our opinion, it should be added among the serum prognostic biomarkers that are able to stratify patients into different prognostic categories even when performed in the early phases of the disease.

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