1. To determine presence and severity of anemia: Anemia refers to low hemoglobin
concentration
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or oxygen-carrying capacity of blood.Clinical signs of anemia (pallor of skin, conjunctival vessels, or
mucous membranes are unreliable for diagnosis of anemia.
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2. Screening for polycythemia: Polycythemia refers to
increased hemoglobin level above the normal range.
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It may be primary, secondary, or relative .3. To assess response to specific therapy in anemia.
4. Estimation of red cell indices (along with packed cell
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volume and red cell count) i.e. mean cell hemoglobin and mean cell hemoglobin
concentration.
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5. Selection of blood donors.Sahli's Acid Hematin Method :
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Principle: Blood is mixed with an acid solution so thathemoglobin is converted to brown-colored acid hematin.
This is then diluted with water till the brown color
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matches that of the brown glass standard. The
hemoglobin value is read directly from the scale.
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Equipment :
1. Sahli's hemoglobinometer: This consists of Sahli's graduated
hemoglobin tube (marked in grams and percent) and a
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comparator with a brown glass standard.2. 2. Sahli's pipette or hemoglobin pipette (marked at 20 l or
0.02 ml).
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3. Smal glass rod (stirrer).
4. Dropping pipette.
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Reagents :1.N/10 hydrochloric acid
2. Distilled water
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Specimen: EDTA-anticoagulated venous blood or bloodobtained by skin puncture.
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Method :
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1.Place N/10 hydrochloric acid into Sahli's graduatedhemoglobin tube up to the mark of 2 grams.
2.Take blood sample in Sahli's pipette exactly up to 20 l mark.
Blood adhering to the exterior of the pipette is wiped away
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using absorbent paper or gauze.3.Add blood sample to the acid solution, mix with a glass stirrer,
and allow to stand for 10 minutes.
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4. Add distilled water drop by drop till the color of the solutionmatches that of the glass standard.
5.Take the reading of the lower meniscus from the graduated
tube in grams
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Disadvantages :
? About 95% color of acid hematin is attained at the end of 10 minutes.For
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maximumcolor development, much longer time (1 hour) is required.
? Perfect matching with the brown glass standard is not possible.
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? Carboxyhemoglobin, methemoglobin, and sulfhemoglobin are not converted toacid hematin. HbF is also not converted to acid hematin and therefore this
method
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is not suitable in small infants.
? Development of color is slow and acid hematin solution is not stable.
? Source of light (daylight or artificial) will influence
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the visual comparison of colors.
? Personal error in matching brown glass standard with test solution is 10%.
? Color of brown glass standard fades with time.
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REFERENCE RANGES (WORLD HEALTH ORGANIZATION):
? Adult males: 13.0 - 17.0gm/dl.
? Adult females (non-pregnant): 12.0 ? 15.0gm/dl.
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? Adult females (pregnant): 11.0 - 14.0 gm/dl.? Children, 6-12 years: 11.5 - 15.5 gm/dl.
? Children, 6 months to 6 years: 11.0 ? 14.0 gm/dl.
? Children, 2 ? 6 months: 9.5 ? 14.0 gm/dl.
? At birth (full term): 13.6 ? 19.6gm/dl.
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CRITICAL VALUES :
? < 7 gm/dl (severe anemia)
? > 20 gm/dl (hyperviscosity)
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Other methods :
1. Colorimetric methods: In these methods, color comparison is made between the
standard and the test sample, either visually or by colorimetric methods.
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? Visual methods: Tallqvist chart, Sahli's acid hematin method, and
WHO hemoglobin color scale.
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? Photoelectric methods: Cyanmethemoglobin (hemiglobincyanide)method, oxyhemoglobin method, and alkaline hematin method.
2.Gasometric method .
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3.Chemical method.
4.Specific gravity method .
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