Fructosamine assay-utility

Understanding Fructosamine: Fructosamine is generated when glucose reacts with the amino groups of proteins, primarily albumin, in a process known as the Amadori rearrangement. This reaction involves the reversible formation of a Schiff base, followed by a series of rearrangements and stabilization, resulting in the formation of fructosamine. The reaction occurs spontaneously and depends on the concentration of glucose and the availability of proteins with free amino groups.

It serves as an indicator of average blood glucose levels over a shorter time frame compared to HbA1c. The formation of fructosamine depends on the rate of glucose production and the lifespan of serum proteins, making it an ideal marker for assessing glycemic control over the preceding 2-3 weeks.

Method of fructosamine estimation:

There are two main methods that are used to measure serum or plasma fructosamine: dye-binding and
enzymatic. In the dye binding method , fructosamine reduces nitroblue tetrazolium (NBT) dye forming a colored endproduct formazan under alkaline conditions. The rate of formazan formation is directly proportional to the fructosamine concentration which is measured with the spectrophotometric technique. This method suffers from various sources of interference (for example, bilirubin, hemoglobin, ascorbic acid, etc.)
In the enzymatic method proteinase K is used to digest the glycated protein to yield glycated protein fragments.

Reference range : 205-285 umol/L

For non diabetic person range should be below 175- 280 mmol/L

For controlled diabetes fructosamine range should be 210-421mmol/L

Advantages of Fructosamine:

1. Fructosamine or glycated albumin are medium-term markers for diabetes, useful when
HbA1c cannot be used such as in patients with hemoglobin variants like sickle cell anemia

2. In conditions where RBC turnover is high like vitamin B12 and Folic acid deficiency, iron deficiency anemia , hemolytic anemia fructosamine serves as a reliable marker of glycemic status

2. Monitoring gestational diabetes: Fructosamine is particularly useful in monitoring blood glucose control during pregnancy. Its ability to provide a more immediate reflection of glycemic control aids in adjusting treatment plans to ensure optimal outcomes for both the mother and the baby

3. Glycated albumin has been reported to be a better marker than HbA1c  for the assessment of glucose control in people with diabetes with chronic kidney disease and those on hemodialysis and peritoneal dialysis

Limitations in fructosamine estimation:

1. Assay should not be performed if serum albumin level is less than 3.0mg/dl

2. Fructosamine assay is not reliable in all conditions that affect serum albumin like hepatic failure,cirrhosis,nephrotic syndrome, paraproteinemia,chronic kidney disease

3. High levels of ascorbic acid interfere with the fructosamine assay. Patients should abstain from ascorbic acid supplements for a minimum of 24 hours prior to sample collection.

Conclusion: Fructosamine is a valuable diabetes marker that offers unique advantages in assessing short-term glycemic control. Its ability to provide a more immediate reflection of blood glucose levels makes it a powerful tool for optimizing diabetes management. While HbA1c remains the gold standard for long-term monitoring, the integration of fructosamine measurements complements it by providing timely and individualized insights. As healthcare providers continue to refine diabetes management strategies, fructosamine holds immense potential in improving overall outcomes for individuals living with diabetes.

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