Clinical Pathologic Tests Essay Discussion Paper
What types of interferences will cause a falsely decreased iron level?
Interference are substances which affects the results of clinical pathologic tests.
They can be lipids, free hemoglobin, bilirubin and drugs.
It can be due to either artefacts in laboratory device or due to underlying pathology in the human body or due to Improper handling technique.
These substance can be analytical or preanalytical.
Those substance which directly affect the test performance are analytical variables.
Those substance which can be controlled to some extent and their effect can be minimized by improvised method of sample collection and handling are preanalytical variables.
Different contributing variables are:
Increased bilirubin Improper handling technique EDTA contamination
It can be an invitro artifact due to
- poor venipuncture technique
- Freezing of whole blood samples
- Delayed separation of serum or plasma from cells
Invivo causes are
- Intravascular Hemolysis due to
- Paroxysmal nocturnal hemoglobinuria
- Mismatched blood transfusion
- Extravascular hemolysis due to
- Sickle cell anemia
- Hereditary spherocytosis and elliptocytosis
When hemolysis occur free iron binds to transferrin and increases total iron binding capacity.
Thus falsely decreasing iron levels.
It is caused by increased triglycerides and cholesterol in the blood.
- Familial hypolipoproteinemia
- Metabolic syndrome
Iron levels are measured with the help of photo spectrometry.
Excess lipids can scatter the light passing through it causing falsely decreased iron levels.
It can be either conjugated or uncongugated hyperbilirubinemia.
Causes can be
- Pre hepatic leading to hemolytic jaundice
- Hepatic leading to hepatocellular jaundice
- Post hepatic leading to obstructive jaundice
Bilirubin can bind to transferrin and can compete with iron leading to falsely reduced iron levels.
EDTA is a chelating agent that is used as anticoagulant I vacutainers.
It binds with iron forming complex which can lead to falsely reduced iron levels.
Out of all the causes most common interference is hemolysis.
In order to reduce error additional measures can be taken:
- Ferritin levels and reticulocyte count can be measured for testing iron levels.
- Instead of edta ,heparinized vacutainer can be used. Clinical Pathologic Tests Essay Discussion Paper