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This site contains a comprehensive list of medical PG entrance questions asked in various PG entrance examination throughout India like AIIMS, AIPGEE, PGI CHANDIGARH, JIPMER, CMC VELLORE .... and various state entrance exams like KERALA, TAMIL NADU, KARNATAKA, DELHI .... and also private entrances like COMEDK, MANIPAL etc...
Naked Eye Single Tube Red Cell Osmotic Fragility Test (NESTROFT)
The principle of NESTROFT is based on the limit of hypotonicity which the red cell can withstand. In this procedure 2 ml of 0.36% buffered saline is taken in a test tube, 20ml of whole blood is added to it, and is allowed to stand at room temperature. After 20 minutes reading is taken on a NESTROFT stand on which a thin black line is marked. If the line is visible through the solution, the test is considered as negative and if line is not visible it is considered as positive. Positive test is due to the reduced osmotic fragility of red cells (Fig. 1).
Fig. 1. NESTROFT stand showing positive and negative samples in different tubes. Tubes from L to R: Tubes 1-3 and 6-8 are positive samples where black line is not visible through the solution, Tubes 4-5 and 9-10 negative samples where black line is visible through the solution.