Write a short note on describe any two methods for diagnosis of G6PD deficiency.

Diagnosis of G6PD Deficiency: Methods

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic disorder characterized by reduced activity of the G6PD enzyme, leading to hemolytic anemia upon exposure to certain triggers. Diagnosis of G6PD deficiency is essential for appropriate management and avoidance of hemolytic crises. Two common methods for diagnosing G6PD deficiency include:

1. Enzyme Assay:

• Enzyme assays measure the activity of the G6PD enzyme in red blood cells (RBCs) and are considered the gold standard for diagnosing G6PD deficiency.
• The most commonly used assay is the quantitative spectrophotometric assay, which measures the rate of NADPH production by G6PD from the oxidation of glucose-6-phosphate.
• Blood samples are collected and treated with a substrate solution containing glucose-6-phosphate and NADP+. The rate of NADPH production, proportional to G6PD activity, is measured spectrophotometrically.
• G6PD activity is expressed as units per gram of hemoglobin or as a percentage of normal activity. Individuals with G6PD activity below a certain threshold are diagnosed with G6PD deficiency.

2. Fluorescent Spot Test (FST):

• The fluorescent spot test is a rapid, qualitative screening test for G6PD deficiency that detects the presence of fluorescent precipitates in RBCs indicative of reduced G6PD activity.
• Blood samples are spotted onto filter paper containing a fluorescent dye and incubated to lyse RBCs. G6PD-deficient RBCs lack sufficient enzyme activity to produce fluorescent precipitates, while normal RBCs generate fluorescence due to NADPH production.
• The filter paper is examined under ultraviolet light, and the presence or absence of fluorescent spots indicates the presence or absence of G6PD deficiency.
• While the FST is convenient and cost-effective for large-scale screening programs, it may lack sensitivity and specificity compared to enzyme assays, leading to false-positive or false-negative results in some cases.

Conclusion:

• Enzyme assays and fluorescent spot tests are two commonly used methods for diagnosing G6PD deficiency. While enzyme assays provide quantitative measurements of G6PD activity and are considered the gold standard, fluorescent spot tests offer rapid and convenient screening for G6PD deficiency, particularly in resource-limited settings. Both methods play important roles in diagnosing G6PD deficiency and guiding appropriate clinical management.