# Flow Cytometry as a New Accessible Method to Evaluate Diagnostic Osmotic Changes in Patients with Red Blood Cell Membrane Defects

## TL;DR

This paper introduces a new flow cytometry method to diagnose red blood cell membrane defects like hereditary spherocytosis, offering a simpler and accessible alternative to current techniques.

## Contribution

A novel flow cytometry-based diagnostic method for red blood cell membrane defects is proposed and validated with high accuracy.

## Key findings

- The flow cytometry method achieved 100% sensitivity and 93.3% specificity in pediatric patients.
- In adults, the method showed 80% sensitivity and 90.9% specificity for diagnosing spherocytosis.
- The technique is easily replicable and could replace less accessible diagnostic methods like osmotic gradient ektacytometry.

## Abstract

Hereditary spherocytosis (HS) is a membranopathy that impacts the vertical junctions between the cytoskeleton and the plasma membrane of erythrocytes. The gold standard method for diagnosing it is osmotic gradient ektacytometry (OGE). However, access to this technique is scarce. We have devised a straightforward approach utilizing flow cytometry to quantify variations in an osmotic gradient, relying on FSC-H/SSC-H patterns. We studied 14 patients (9 pediatric, 5 adults) and 54 healthy controls (16 pediatric, 38 adults). After assessing the behavior of the samples in several osmolar gradients we selected for the study the 176, 308, and 458 mOsm/kg levels as hypo-osmolar, iso-osmolar, and hyper-osmolar references. We then selected the iso-osmolar point for assessment to determine its efficacy in discriminating between patient and control groups using a receiver operating characteristic curve. In the pediatric group, the area under the curve (AUC) was 1.0, indicating 100% sensitivity and 93.3% specificity. Conversely, in the adult group, the AUC was 0.98, with 80% sensitivity and 90.9% specificity. We introduce a method that is easily replicable and demonstrates high sensitivity and specificity. This technique could prove valuable in the diagnosis of spherocytosis.