Ectacytometry
The term ectacytometry describes a method of examining the deformability of erythrocytes that is used in medicine and was first described in 1980.
principle
In ectacytometry, erythrocytes are exposed to a defined shear force in a viscous solution and their elongation, i.e. the degree of their deformation, is measured. This is done by suspending the erythrocytes to be tested in a viscous liquid (usually a dextran solution) . The mixture is then pumped into a double cylinder and the outer cylinder rotated around the inside. This creates a calculable shear force that is dependent on the speed and acts on the erythrocytes. The diffraction pattern of the deformed erythrocytes can be determined by a laser that passes through the two cylinders and the erythrocyte suspension they contain . From this, the deformation index DI is calculated, which corresponds to the quotient of the measured deformation and the deformation without shear force.
Osmotic gradient ectacytometry
The osmotic gradient ectacytometry is the most meaningful further development of the ectacytometry in practice. Here, the erythrocyte sample to be tested is ectacytometry with continuously changing osmolarity . This creates a curve, the ectacytogram , with the osmolarity as the abscissa and the deformability index as the ordinate . Using this curve, some parameters of the blood examined can be read:
- The osmolarity at which 50% of erythrocytes hemolyze . The significance of this value is comparable to that of an osmotic resistance test .
- The maximum deformability of the erythrocytes
- The behavior of deformability in the hyperosmolar environment
Diagnostic significance
Hereditary hemolytic anemias can be characterized more precisely by means of osmotic gradient ectacytometry; in particular, disorders of the erythrocyte membrane can be clearly identified. Ectacytometry is also able to provide information about the current state of the disease. Examples of such diseases are hereditary spherocytosis and ellipsocytosis . However, there are indications that the deformability of the erythrocytes is also impaired in other diseases, which could be described more precisely using ectacytometry. Nevertheless, the ectacytometry is to be regarded as experimental, the evaluation requires a certain experience with this method and precise knowledge of the many possible confounding factors.
relevance
Ectacytometry is a very seldom used method and is only offered at very few university centers, in German-speaking countries only at the Clinic for Hematology at the University Hospital Zurich .
Individual evidence
- ^ Bessis, Mohandas and Feo Automated ektacytometry: a new method of measuring red cell deformability and red cell indices in Blood Cells. 1980; 6 (3): 315-327, PMID 7397390 .
- ↑ Groner, Mohandas and Bessis New Optical Technique for Measuring Erythrocyte Deformability with the Ektacytometer In: Clin. Chem. 26/10, 1435-1442 (1980), PMID 6996869 .
- ↑ Clark, Mohandas and Shohet: Osmotic gradient ektacytometry: comprehensive characterization of red cell volume and surface maintenance in Blood. 1983 May; 61 (5), 899-910, PMID 6831052 .
