Clinical Pathologic Tests Essay Discussion Paper

Question

What types of interferences will cause a falsely decreased iron level?

Step 1/3

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.

Step 2/3

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:

Hemolysis

Lipemia

Increased bilirubin Improper handling technique EDTA contamination

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Step 3/3

Hemolysis

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
Favism

Extravascular hemolysis due to

Sickle cell anemia
Thalassemia
Hereditary spherocytosis and elliptocytosis

When hemolysis occur free iron binds to transferrin and increases total iron binding capacity.

Thus falsely decreasing iron levels.

Lipemia

It is caused by increased triglycerides and cholesterol in the blood.

Causes are:

Familial hypolipoproteinemia
Obesity
Metabolic syndrome
Hypothyroidism

Iron levels are measured with the help of photo spectrometry.

Excess lipids can scatter the light passing through it causing falsely decreased iron levels.

Increased bilirubin

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 Contamination

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.

Final answer

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