Anemia Biomarker
Collection Type: Blood
Related System: Anemia
The Sickle Cell Solubility Test (and the related sickling phenomenon observation) is a screening method to detect hemoglobin S (HbS), the abnormal hemoglobin responsible for sickle cell trait and sickle cell disease. The solubility test detects insoluble deoxygenated HbS by producing turbidity in a reducing solution; a separate “sickling” test shows red blood cells taking a crescent shape under low-oxygen conditions on a blood smear. It is used when patients present with unexplained anemia, episodic pain (vaso‑occlusive crises), jaundice, dactylitis, recurrent infections, or family/ethnic risk. Results can be affected by age (newborns with high fetal hemoglobin may give false negatives), recent transfusion, or treatment (e.g., hydroxyurea); gender has no direct effect.
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Symptom CheckerNegative no hemoglobin S detected (qualitative result)
Q: What is the principle of sickling solubility test?
A: The sickling solubility test detects haemoglobin S by exploiting its reduced solubility when deoxygenated. A reducing agent (e.g., sodium metabisulfite/dithionite) rapidly deoxygenates blood; deoxy‑HbS polymerizes and precipitates, producing turbidity. Normal haemoglobins stay soluble and yield a clear solution. The test screens for presence of HbS but does not quantify or distinguish sickle trait from disease.
Q: What does a negative solubility test for sickle cell mean?
A: A negative sickle‑cell solubility test means no detectable sickle hemoglobin (HbS) in the sample, making sickle cell trait or disease unlikely. False negatives can occur in newborns (high fetal hemoglobin), after recent transfusion, or with very low HbS levels. If clinical suspicion or family history exists, confirm with definitive testing such as hemoglobin electrophoresis, HPLC, or genetic testing.
Q: What is the sickling test for sickle cell anemia?
A: The sickling test is a rapid screening method for sickle cell disease that deoxygenates a blood sample (commonly with sodium metabisulfite) and examines red cells microscopically for crescent-shaped (sickled) forms. A positive result suggests presence of sickle hemoglobin but does not distinguish trait from disease; confirmatory tests (hemoglobin electrophoresis/HPLC) are required. Recent transfusion can cause misleading results.
Q: What are the two confirmatory tests for sickle cell anemia?
A: The two primary confirmatory tests for sickle cell anemia are hemoglobin electrophoresis and high-performance liquid chromatography (HPLC). Both identify and quantify abnormal hemoglobin variants such as HbS and distinguish sickle cell disease from trait. These tests follow positive screening results; molecular (DNA) testing of the HBB gene may be used additionally for prenatal diagnosis or unclear cases.
Q: What is the reagent used in sickle cell solubility test?
A: The primary reagent used in the sickle cell solubility test is sodium dithionite (sodium hydrosulfite). It reduces hemoglobin to the deoxygenated form; deoxy‑HbS is relatively insoluble and causes turbidity when mixed with a buffered hemolysate. This rapid screening test detects HbS presence but does not quantify variants or replace confirmatory methods like electrophoresis or HPLC.
Q: What is the difference between sickling and sickle cell?
A: Sickling is the process when red blood cells containing abnormal hemoglobin S become rigid and crescent-shaped when deoxygenated. \