[The modified "pink test" in the diagnosis of hereditary spherocytosis]

Hereditary spherocytosis is still difficult to diagnose in some situations due to the existence of subclinical expressions and the lack of an accurate test with high sensitivity and specificity. Recently, Vettore et al. described the so-called 'Pink test' as an easy method with the highest reproducibility and sensitivity. Herein, we present our experience with the 'Pink test' in the diagnosis of 16 previously diagnosed hereditary spherocytosis patients comparing the results with those obtained in 96 healthy controls, 41 beta-thalassaemias, 9 autoimmune haemolytic anaemias, 8 chronic hemoproliferative syndromes and 2 patients with pyruvate kinase deficiency. We also present a modification of the original 'Pink test' in which a small sample of blood (200 microL) obtained by finger-prick (or heel puncture in newborns and infants) is mixed with the hemolyzing solution of the 'Pink test' within the first three hours after blood drawing. Elevated correlation coefficients (r = 0.75-0.96) between both methods have been obtained comparing the percentage of final haemolysis in 25 healthy controls, 21 beta-thalassaemia minor and 9 hereditary spherocytosis patients.