Ektacytometry is a specialized laboratory technique used to measure the deformability and mechanical properties of red blood cells (RBCs).
By subjecting blood cells to shear stress and measuring their shape change using laser diffraction, clinicians can diagnose various hematological disorders.
RBCs are suspended in a viscous medium and placed between two concentric cylinders—one stationary and one rotating.
A laser beam is directed through the suspension, and as the cells rotate and elongate under shear stress, they create an elliptical diffraction pattern.
An instrument calculates an “Elongation Index” based on the height and width of the diffraction pattern, which serves as a quantitative measure of how well the cells can change shape.
Ektacytometry is primarily used to identify conditions where RBCs are rigid or abnormally shaped:
RBC Membrane Disorders: It is the standard for diagnosing Hereditary Spherocytosis and other membrane defects like hereditary elliptocytosis or xerocytosis.
Sickle Cell Disease (SCD): Modern Oxygen Gradient Ektacytometry (“oxygenscan”) measures how cells sickle and lose deformability as oxygen levels drop, helping to monitor treatment response and predict disease severity.
Osmotic Gradient Ektacytometry (Osmoscan): Measures deformability across a range of salt concentrations (osmolality) to assess cellular hydration and surface-area-to-volume ratio.
Oxygen Gradient Ektacytometry (Oxygenscan): Measures deformability as oxygen tension is gradually reduced, specifically used for Sickle Cell Disease research and care.
Ektacytometry provides characteristic deformability profiles: HS shows decreased maximal deformability with right-shifted osmotic fragility: xerocytosis demonstrates left-shifted curves; HE displays trapezoidal patterns.
Osmotic gradient Ektacytometry provides a curve that demonstrates decreased normal, or increased osmotic fragility, and also measures the deformability of the red blood cell, a parameter affected by membrane skeleton mechanics as the RBC’s are exposed to an osmolality gradient.
Ektacytometry distal curve depends on intercellular viscosity of erythrocytes and may be affected by hemoglobin concentration and hydration status of the cell.
The ektacytometry curve is characteristic for each type of red cell membraneopathy, providing a differential among HS, HX, HE/HPP, OHSt and Southeast Asian ovalocytosis.