Quick Review Cards for Medical Laboratory Science

Manual Hematology Procedurescontinued Hematology Review 328

TEST PURPOSE METHOD COMMENTS

Tube solubility

screening test for

Hemoglobin S

Osmotic fragility

Donath-Landsteiner

(DL) test

Screening for

Hgb S

Dx of hereditary

spherocytosis

Dx of paroxys-

mal cold

hemoglobinuria

Blood mixed with reducing agent, e.g.,

sodium dithionite. Hgb S is insoluble,

produces turbid solution that obscures

black lines behind tube.

Blood added to serial dilutions of NaCl &

incubated. Amount of hemolysis deter-

mined by reading absorbance of super-

natant from each tube.

Blood collected in 2 clot tubes. Tube 1

incubated at 4°C, then 37°C. Tube 2 in-

cubated at 37°C only. Pos = hemolysis in

Tube 1, none in Tube 2.

Not specific for Hgb S. Doesn’t differentiate

SS from AS. Follow up with hgb elec-

trophoresis.

↑in hereditary spherocytosis. ↓with target

cells, sickle cell anemia, iron deficiency ane-

mia, thalassemia.

Rare autoimmune hemolytic anemia due to

biphasic antibody (autoanti-P) that binds

complement to RBCs in capillaries at <20°C

& elutes off at 37°C. Complement remains

attached & lyses cells.

CRP = C-reactive protein.