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Rate of change in plasma fructosamine concentration in diabetic cats
A D VA N C E S
PAG E 5
wide. The critical difference for fructosamine was 33 μmol/l.
Author Conclusion
RATE OF CHANGE IN PLASMA FRUCTOSAMINE CONCENTRATION IN DIABETIC CATS Background Fructosamine is a collective term for glycated plasma proteins. Plasma concentration of fructosamine is related to mean blood glucose concentration. Plasma fructosamine concentration has been used for the diagnosis and monitoring of canine and feline diabetes mellitus for more than 20 years. In humans, plasma fructosamine concentration reflects the mean blood glucose over the preceding 2 to 3 weeks, a time span related to the half-life of plasma proteins. The half-life of plasma proteins and fructosamine in the cat is unknown.
Objectives To determine the time required for plasma fructosamine concentration to increase after the onset of hyperglycemia and decrease after resolution of hyperglycemia in cats.
Procedure Fourteen healthy cats were infused to maintain either moderate hyperglycemia (mean glucose of 17 nmol/l) in 5 cats or marked hyperglycemia (mean of 29 mmol/l) in 9 cats for 42 days. Plasma fructosamine concentrations were measured periodically throughout the infusions.
Results Fructosamine exceeded the upper limit of the reference range (331 μmol/l) after 3 to 5 days of marked hyperglycemia. It required 20 days to plateau and took 5 days to return to baseline after infusion ceased. Fructosamine concentration for moderate hyperglycemia took longer to exceed the reference range (mean of 7 days), fewer days to plateau (8 days), and return to baseline (1 day). In cats with moderate hyperglycemia, fructosamine concentration mostly fluctuated within the upper limit of the reference range. The range of fructosamine concentrations associated with a given glucose concentration was
Serial plasma fructosamine concentrations in an individual cat over time may provide more useful information on diabetic control, rather than attempting to extrapolate a mean glucose concentration from the plasma fructosamine concentration.
Inclusions Four figures, 30 references.
Editor Annotation This study generated some new and useful information for interpreting plasma fructosamine level in hyperglycemic cats. A main aim was to determine the time required for hyperglycemia to cause changes in plasma fructosamine concentration in cats. To study this, the authors infused normal cats to induce various degrees of hyperglycemia. Cats with severe hyperglycemia (more than 500 mg/dl) showed elevation in plasma fructosamine as soon as 3 days after initiation of severe hyperglycemia, while moderate hyperglycemia (300 mg/dl) increased fructosamine concentration after about a week’s time. When hyperglycemia was ameliorated, the fructosamine level quickly declined. From these data, it can be concluded that the plasma fructosamine level in cats probably reflects the prevailing plasma glucose concentration for the prior week. The fructosamine test is widely used by veterinarians to diagnose and manage diabetes in cats, but drawbacks of its use are often not appreciated. Like most diagnostic tests, the fructosamine level is not a perfect test. Although it is generally considered a reasonably sensitive test, an interesting finding of the current study was that 6 weeks of persistent moderate hyperglycemia did not always result in a fructosamine level that exceeded the reference range. In that situation, sole reliance on the fructosamine test may confound the diagnosis of cats with mild diabetes. Fructosamine also suffers from nonspecificity in cats, and results can be affected by diverse factors, such as hyperlipidemia, serum protein concentration, and hyperthyroidism. An unexpected finding from the current study was that ketosis also appears to influence the fructosamine level. Insulin treatment of cats with ketosis caused a
PA G E 6
A D VA N C E S
significant decrease in fructosamine concentration, even though no change occurred in the glucose concentration. Because of the varied and somewhat unpredictable influence of extraneous factors on plasma fructosamine concentration, fructosamine levels determined at admission when the cat may be dehydrated or ketotic must be interpreted with caution. Initially measured plasma fructosamine levels may be an inappropriate baseline for evaluation of diabetic control. (TS) Link KR, Rand JS. Changes in blood glucose concentration are associated with relatively rapid changes in circulating fructosamine concentrations in cats. J Feline Med Surg 2008;10:583-592.
PAG E 5
wide. The critical difference for fructosamine was 33 μmol/l.
Author Conclusion
RATE OF CHANGE IN PLASMA FRUCTOSAMINE CONCENTRATION IN DIABETIC CATS Background Fructosamine is a collective term for glycated plasma proteins. Plasma concentration of fructosamine is related to mean blood glucose concentration. Plasma fructosamine concentration has been used for the diagnosis and monitoring of canine and feline diabetes mellitus for more than 20 years. In humans, plasma fructosamine concentration reflects the mean blood glucose over the preceding 2 to 3 weeks, a time span related to the half-life of plasma proteins. The half-life of plasma proteins and fructosamine in the cat is unknown.
Objectives To determine the time required for plasma fructosamine concentration to increase after the onset of hyperglycemia and decrease after resolution of hyperglycemia in cats.
Procedure Fourteen healthy cats were infused to maintain either moderate hyperglycemia (mean glucose of 17 nmol/l) in 5 cats or marked hyperglycemia (mean of 29 mmol/l) in 9 cats for 42 days. Plasma fructosamine concentrations were measured periodically throughout the infusions.
Results Fructosamine exceeded the upper limit of the reference range (331 μmol/l) after 3 to 5 days of marked hyperglycemia. It required 20 days to plateau and took 5 days to return to baseline after infusion ceased. Fructosamine concentration for moderate hyperglycemia took longer to exceed the reference range (mean of 7 days), fewer days to plateau (8 days), and return to baseline (1 day). In cats with moderate hyperglycemia, fructosamine concentration mostly fluctuated within the upper limit of the reference range. The range of fructosamine concentrations associated with a given glucose concentration was
Serial plasma fructosamine concentrations in an individual cat over time may provide more useful information on diabetic control, rather than attempting to extrapolate a mean glucose concentration from the plasma fructosamine concentration.
Inclusions Four figures, 30 references.
Editor Annotation This study generated some new and useful information for interpreting plasma fructosamine level in hyperglycemic cats. A main aim was to determine the time required for hyperglycemia to cause changes in plasma fructosamine concentration in cats. To study this, the authors infused normal cats to induce various degrees of hyperglycemia. Cats with severe hyperglycemia (more than 500 mg/dl) showed elevation in plasma fructosamine as soon as 3 days after initiation of severe hyperglycemia, while moderate hyperglycemia (300 mg/dl) increased fructosamine concentration after about a week’s time. When hyperglycemia was ameliorated, the fructosamine level quickly declined. From these data, it can be concluded that the plasma fructosamine level in cats probably reflects the prevailing plasma glucose concentration for the prior week. The fructosamine test is widely used by veterinarians to diagnose and manage diabetes in cats, but drawbacks of its use are often not appreciated. Like most diagnostic tests, the fructosamine level is not a perfect test. Although it is generally considered a reasonably sensitive test, an interesting finding of the current study was that 6 weeks of persistent moderate hyperglycemia did not always result in a fructosamine level that exceeded the reference range. In that situation, sole reliance on the fructosamine test may confound the diagnosis of cats with mild diabetes. Fructosamine also suffers from nonspecificity in cats, and results can be affected by diverse factors, such as hyperlipidemia, serum protein concentration, and hyperthyroidism. An unexpected finding from the current study was that ketosis also appears to influence the fructosamine level. Insulin treatment of cats with ketosis caused a
PA G E 6
A D VA N C E S
significant decrease in fructosamine concentration, even though no change occurred in the glucose concentration. Because of the varied and somewhat unpredictable influence of extraneous factors on plasma fructosamine concentration, fructosamine levels determined at admission when the cat may be dehydrated or ketotic must be interpreted with caution. Initially measured plasma fructosamine levels may be an inappropriate baseline for evaluation of diabetic control. (TS) Link KR, Rand JS. Changes in blood glucose concentration are associated with relatively rapid changes in circulating fructosamine concentrations in cats. J Feline Med Surg 2008;10:583-592.