Acid Hematin Method
The acid hematin method is a common laboratory test used to determine the concentration of hemoglobin in a blood sample.
Hemoglobin is a protein found in red blood cells that carries oxygen throughout the body.
The acid hematin method involves the conversion of hemoglobin to acid hematin, which is then measured calibration tube.
This is also known as Sahli’s method. It is recommended for places where a colorimeter is not available.
It is not a recommended method because all forms of hemoglobin are not converted to acid hematin and colour does not vary strikingly due to change in hemoglobin concentration.
Acid Hematin Method Principle
Hemoglobin is converted to acid hematin by the action of hydrochloric acid. The acid converts the hemoglobin molecule to acid hematin by removing the iron from the heme group, resulting in the formation of a stable compound. The acid hematin solution is further diluted with the acid until its colour matches exactly that of the permanent standard of the comparator block. The hemoglobin concentration is read directly from the calibration tube. The amount of acid hematin produced is proportional to the amount of hemoglobin in the sample.
Sahli’s method requirements
- 0.1 N hydrochloric acid
- Sahli’s hemoglobinometer
- Sahli’s pipette (20 μL)
- Calibrated tubes of hemoglobinometer
Acid Hematin Method Procedure
- The acid hematin method involves the following steps:
- Collect a blood sample from the patient using a venipuncture.
- Transfer a measured volume of the blood sample to a test tube.
- Fill the specially marked calibrated tube of hemoglobinometer up to the 10 mark with 0.1 N HCI.
- Draw the blood specimen into Sahli’s pipette (20ul).
- Make sure the anticoagulated blood is mixed so that no air bubble has entered into the pipette while taking the blood sample.
- Wipe the outside of sahli’s pipette with a cloth or cotton.
- Check the level of the blood in the pipette
- Blow the blood into the acid solution inside the graduated tube.
- Wash out the contents of the pipette by repeated drawing in and blowing out of the diluting fluid.
- Allow the mixture to stand at room temperature for 10 minutes and then place the graduated tube in the hemoglobinometer and face a window for better lighting from the back.
- Compare the color of the diluted blood in the tube with the reference tube.
- If the colour is the same, then the hemoglobin concentration is recorded.
- If the colour is darker, then the contents of the tube is diluted with 0.1 N HCI or distilled water drop by drop and stirred using glass rod till the colour of the contents match with the comparator.
- Hemoglobin concentration is then recorded.
Acid Hematin Method Results
If the colour is the same, then the hemoglobin concentration is recorded.
If the colour is darker, then the contents of the tube is diluted with 0.1 N HCI or distilled water drop by drop and stirred using glass rod till the colour of the contents match with the comparator.
Hemoglobin concentration is then recorded.
The results of the acid hematin method are reported as the hemoglobin concentration in grams per deciliter (g/dL) of blood. Normal values for hemoglobin concentration vary depending on age, sex, and other factors. In adult males, the normal range is 13.5-17.5 g/dL, while in adult females, the normal range is 12.0-15.5 g/dL.
Clinical Manifestations of Acid Hematin Method
The acid hematin method is used to measure the concentration of hemoglobin in the blood, which is important for the diagnosis and management of various medical conditions such as anemia, bleeding disorders, and polycythemia. The test is also used to monitor the response to treatment in patients with these conditions.
Uses
- The acid hematin method is a commonly used laboratory test to measure hemoglobin concentration in the blood.
- It is used for the diagnosis and management of various medical conditions such as anemia, bleeding disorders, and polycythemia.
- The test is also used to monitor the response to treatment in patients with these conditions.
Limitations
- The acid hematin method has some limitations. It requires careful handling of the blood sample to ensure accurate results.
- The test may be affected by hemolysis, lipemia, or icterus, which can interfere with the accuracy of the results.
- In addition, the acid hematin method may not detect certain types of hemoglobin variants, which can result in false-negative results.
- Finally, the test may be affected by other factors such as altitude, smoking, and pregnancy, which can affect the hemoglobin concentration in the blood.
