Evaluation of single-tube osmotic fragility as a screening test for thalassemia

Am J Hematol. 2005 Jul;79(3):198-201. doi: 10.1002/ajh.20387.


A single-tube osmotic fragility test has been proposed for thalassemia screening with a range of different concentrations of saline having been employed. We have compared the sensitivity and specificity of 0.32%, 0.34%, and 0.36% buffered saline, and on the basis of our findings, recommend the use of 0.36% saline. This gave definitely positive or equivocal results in 81 of 85 patients with beta thalassemia trait and in 4 of 4 with alpha(0) thalassemia trait. There were 14% false positive results in hematologically normal patients and 81% of the samples from patients with various variant hemoglobins gave positive results. The sensitivity was 95% and specificity 86%. The single-tube osmotic fragility test is potentially useful in under-resourced laboratories although it cannot replace automated red cell indices using electronic counters.

Publication types

  • Evaluation Study

MeSH terms

  • False Positive Reactions
  • Hemoglobin E
  • Hemoglobinopathies / diagnosis
  • Humans
  • Mass Screening / economics
  • Mass Screening / methods*
  • Mass Screening / standards
  • Osmotic Fragility*
  • Sensitivity and Specificity
  • Sodium Chloride
  • Thalassemia / diagnosis*
  • alpha-Thalassemia / diagnosis
  • beta-Thalassemia / diagnosis


  • Sodium Chloride
  • Hemoglobin E