Figure 1. Sickle cell solubility test in the laboratory. The presence of hemoglobin S is marked by a turbid solution (on the left). The control solution is clear, allowing for visualization of the lines (right).
Figure 2. Hemoglobin S (HbS) percentage with concomitant sickle cell solubility testing (SCST) in 220 distinct samples in patients with sickle cell disease (SCD), sickle cell trait (SCT) or HbAA. These samples were taken from 112 patients with SCD of all genotypes, 16 patients with SCT, and one patient without SCD or SCT. SCD patients were further subdivided by genotype: HbSS, HbSC, HbS-beta thalassemia null, or HbS-beta thalassemia positive. Of the 220 samples, five were false negative (large circles). These all occurred at an HbS level < 15%. This subset is highlighted in the blue subsection with individual negative values indicated by the large circles.