How does eating skew a blood test?

[graylocks]

my son had some blood work done last week and the doctor called to say everything was normal. when i told my son he confessed that he had goofed and snacked on 1/2 a banana before he remembered he wasn't supposed to eat. (sigh. it would have been a very simple matter to have gone in for the test another day if he had only told me!)

how might his snack skew his results? the ped was looking to see if my son was still pre-diabetic.

[Robert M]

Gray,

What you eat can impact the levels of the stuff in your blood. For example, the results of a cholesterol test could be skewed if you have a something high in fat just before you take the test, i.e. burger, fries and shake. The sugar contained in the banana could skew the amount of sugar that is in your son's blood when he takes the test. It could take X amount of time before the sugar levels go back to what they are normally.

Robert

[graylocks]

Robert M wrote:
The sugar contained in the banana could skew the amount of sugar that is in your son's blood when he takes the test. It could take X amount of time before the sugar levels go back to what they are normally.

Robert

working with my limited medical/chemical knowledge here - so the banana most likely elevated his glucose level which his doctor read normal. does a higher than standard glucose reading indicate a pre-diabetic state or does a lower than standard glucose reading indicate a pre-diabetic state?

i'm also trying to google this but not hitting results i can easily understand.

[Robert M]

Gray,

Possibly. I'm hoping someone who is more informed than me will jump into the thread and clarify. I know about the impact of fatty foods before a cholesterol from someone who got "talked to" by his doctor. He had a healthful meal of burgers, fries, a shake and a bag of pork rinds as a snack a few hours before his cholesterol test. He forgot about the test and wasn't reminded of it until after he'd stuffed himself. His doctor told him not to take the blood test because his "meal" will have skewed the results entirely.

Robert

[graylocks]

thanks, Robert. i did just find some info that one is pre-diabetic if your glucose is higher than normal. if the banana elevated his reading, it still wasn't high enough to be pre-diabetic so i think we're okay.

the ped wants to retest him in 6 months. i'll watch him more carefully next time - or lock up the food!

[AlphaDog]

Rather than sitting around and worrying about this, I strongly suggest you just call the doctor and ask what the reading was and also explain that your son cheated with a half banana! (Hey, there are worse things a teenage boy could cheat with you know!) That half banana should have, in theory, caused his blood sugar level to increase. So, if it was still within a normal range, I seriously doubt there's a reason to be concerned, but this should be verified, if only for your peace of mind.

"Q: How does the FPG test define diabetes and pre-diabetes?

A: Normal fasting blood glucose is below 100 mg/dl. A person with pre-diabetes has a fasting blood glucose level between 100 and 125 mg/dl. If the blood glucose level rises to 126 mg/dl or above, a person has diabetes.

http://www.diabetes.org/pre-diabetes/pre...mptoms.jsp

[Robert M]

Alpha,

Excellent advice! I should've offered the same advice in my initial response! If in doubt, contact your doctor.

Robert

[SDGuy]

Probably didn't skew things too much - Glycemic Load of 10.

"GL's of 10 or below are considered low, and 20 or above are considered high."

[Mike Sellers]

Robert M wrote: He had a healthful meal of burgers, fries, a shake and a bag of pork rinds as a snack a few hours before his cholesterol test. He forgot about the test and wasn't reminded of it until after he'd stuffed himself. His doctor told him not to take the blood test because his "meal" will have skewed the results entirely.

I wonder if fasting before bloodwork actually skews the results moreso than not fasting. Seems to me, if his regular diet consisted of this type of food, then the results would have been more accurate than if he had fasted before the test.

[SDGuy]

Mike Sellers wrote:
[quote=Robert M]He had a healthful meal of burgers, fries, a shake and a bag of pork rinds as a snack a few hours before his cholesterol test. He forgot about the test and wasn't reminded of it until after he'd stuffed himself. His doctor told him not to take the blood test because his "meal" will have skewed the results entirely.

I wonder if fasting before bloodwork actually skews the results moreso than not fasting. Seems to me, if his regular diet consisted of this type of food, then the results would have been more accurate than if he had fasted before the test.
Don't worry, they can tell what you've been doing for the past three months:
"The HbA1c test, usually called just an "A1c" test, is a long term measure of diabetic control. Over the course of time, glucose and blood fats combine to "coat" some of the red blood cells (hemoglobin) ... sort of like icing a cake. Since red blood cells are being destroyed and re-manufactured every day, by measuring the percentage of them that have this "coating," we can get an idea of how well the person has kept their blood sugar under control long-term. The new cells won't have this coating for a while. The A1c is a measure of how good the control has been for the past 90 days."