A new test for the laboratory diagnosis of spherocytosis, conventionally called 'Pink test', is presented. This test, semi-quantitatively or quantitatively, determines the
hemolysis of small blood samples in a
solution containing
glycerol (135 mmol/l), NaCl (25 mmol/l),
NaN3 (1.5 mmol/l), buffered to pH 6.66 with
Bis-Tris (70 mmol/l) and HCl. 'Pink test', as well as 'acidified'
glycerol lysis test, were positive in 100% of 42 patients suffering from
hereditary spherocytosis, and optimally discriminated them from healthy subjects, showing a diagnostic sensitivity greater than 'standard'
glycerol lysis test and osmotic fragility in hypotonic saline solutions of fresh or incubated blood. 'Pink test' was also positive in some cases of
renal failure, immunohemolytic
anemia, chronic hemoproliferative disorders, normal pregnant women, and negative in other microcytic
anemias (
beta-thalassemia,
iron deficiency anemia). The results do not critically depend on pH of the
solution (differently from those obtained with 'acidified'
glycerol lysis test), and for this reason they show a good reproducibility.