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Reasons, Procedure and Preparation Required For Acidification Test (Ham's Test)

Submitted on March 27, 2012

Acidification (Ham's) Test

Also known as a Ham's Test, an acidification test is used to gauge any increase in the fragility of red blood cells when they are placed in mild acid. A positive test can confirm the diagnosis of PNH, short for paroxysmal nocturnal hemoblobinuria, which is a condition where an abnormal cell surface leads to the premature destruction of the cells. The condition is primarily caused by a defect in the formation of a red cell surface protein anchor - known as GP1. This defect will then contribute to the other surface proteins being unable to remain tethered to the cell surface resulting in enhanced sensitivity to complement mediated cell destruction. The condition is not restricted to any particular age and is known to affect both sexes in equal proportion. The condition is characterized by the low count to red blood cells, white blood cells and platelets as well as a reddish or brownish tinge to the urine as a result of the release of hemoglobin into the circulation and urine after the breakdown of red blood cells.

Reason Why It is Conducted?

Going through an acidified serum test will confirm the diagnosis of PNH, although it is fast becoming rather outdated in comparison to newer tests such as flow cytometry taking its place. The test is also used in the diagnosis of another rare condition known as congenital dyserythropoietic anemia - but will show a negative outcome to confirm the presence of the condition.

Procedure

As with most blood tests, the Acidification test will require a sample of blood be drawn from the arm of the patient after the puncture site has been sufficiently cleansed with an anti septic and an elastic band is placed a little higher up the arm to restrict blood flow to the vein. This will cause the vein to swell with blood - making it more prominent and easy to draw a sample from. After the blood has been drawn with the help of a needle, the puncture site will be covered to prevent any extra loss of blood. Some patients may experience fainting or dizziness just after the drawing of blood while others may merely notice a throbbing around the puncture wound.

Preparation

There are no special preparations that a patient would need to go through prior to the test. Varying from individual to individual however, some of the risks include infection as a result of an unsterilized needle, hematoma or even excessive bleeding.

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