What is the Shine and Lal index?

Shine and Lal Index: A Diagnostic Tool for Differentiating Beta-Thalassemia Trait from Iron Deficiency Anemia

The Shine and Lal index is a mathematical formula calculated as (0.01 × MCH × MCV²) that helps differentiate beta-thalassemia trait from iron deficiency anemia in patients with microcytic anemia. 1

Formula and Calculation

The Shine and Lal index uses red blood cell parameters obtained from automated blood cell analyzers:

• The formula is calculated as: (0.01 × MCH × MCV²) 1, 2
• In some recent studies, a modified version called mSLI is calculated as: (MCV² × MCH) × 0.0001 3
• MCH = Mean Corpuscular Hemoglobin
• MCV = Mean Corpuscular Volume 1

Clinical Application

The primary use of the Shine and Lal index is in the differential diagnosis of microcytic anemias:

• It serves as a screening tool to distinguish between beta-thalassemia trait and iron deficiency anemia, which are the two most common causes of microcytic anemia 4
• The index can be particularly useful in population screening programs, such as during pregnancy, to identify individuals who may need further testing for beta-thalassemia 1
• It has been studied as part of a multi-stage screening process that can reduce the number of people requiring confirmatory testing while maintaining high diagnostic accuracy 1

Diagnostic Performance

The diagnostic performance of the Shine and Lal index varies across different studies and populations:

• In Thai adults, the Shine and Lal index showed reasonable but not optimal performance compared to other discrimination indices 4
• In a study of pregnant women in Singapore, the Shine and Lal index reduced the number of people recalled for confirmatory testing by 31.1% and increased the diagnostic yield to 38.7% while maintaining a negative predictive value of 0.993 1
• In pediatric populations, one study found that the Shine and Lal index had the highest sensitivity (87.1%) among various discrimination indices, though none achieved both 100% sensitivity and specificity 2
• Another pediatric study found that while the Shine and Lal index had utility, other indices such as RBC count and RDWI (Red Cell Distribution Width Index) were more reliable for differentiating beta-thalassemia trait from iron deficiency anemia 5

Comparison with Other Discrimination Indices

Several other formulas exist for the same purpose, and their relative performance should be considered:

• Common alternatives include the Mentzer Index, England and Fraser Index, Srivastava Index, Green and King Index, RBC count, RDW, and RDWI 2, 5
• In some studies, RBC count and RDWI showed higher Youden's Index values (a measure of overall test performance) than the Shine and Lal index 5
• The optimal discrimination index may vary depending on the specific population being studied 4, 2

Limitations and Considerations

Important limitations to consider when using the Shine and Lal index:

• No single discrimination index, including Shine and Lal, has shown 100% sensitivity and specificity across all studies 2, 5
• The performance of the index may vary across different age groups, ethnicities, and clinical contexts 4, 2
• Definitive diagnosis of beta-thalassemia trait still requires hemoglobin electrophoresis or other specific tests to measure HbA₂ levels 2
• The index should be used as a screening tool rather than a definitive diagnostic test 1, 2

Emerging Applications

Beyond its traditional use in differentiating causes of microcytic anemia:

• Recent research has explored the modified Shine and Lal Index (mSLI) as a prognostic marker in non-small cell lung cancer, suggesting potential applications beyond hematological disorders 3
• This emerging application demonstrated that mSLI was an independent prognostic marker for overall survival in stage I-IIIA NSCLC patients 3