Thursday, February 24, 2011

The Problem With Ketone Testing

is that it's nonspecific.

On Friday morning last week, I woke up with a blood sugar in the upper three hundreds. I was a bit surprised, but corrected and moved on. Had breakfast, etc. I was about to leave for work when I spotted the syringe with my dose of Lantus still in it from the previous night- OOPS! I squirted out half of it, and took a normal dose that night.

Later I tested for urine ketones- trace.

I tested for ketones again after a spike Sunday night- trace.

I tested ketones for the heck of it Monday night- trace.

I tested ketones Tuesday night- small.

I tested ketones Wednesday night- negative!

I had the most perfect blood sugar today. I've been under 200 and over 70 for about 29 hours now (range = 73-184), most of it between 80 and 140. My Dexcom's been spot on. I've eaten lots of carbs. My urine ketones are small.
Even though the color doesn't match the vial perfectly, it's very clear that the ketones are positive because I have yesterday's negative strip and the two are extremely obviously not the same color.

I bought up the matter to my mother, who suggested that my ketone strips had gone bad, since I am eating carbs, drinking water, and keeping blood sugar below 240. I also seem to be digesting at least some of the carbs, seeing as how I haven't had any crazy hypos and I am prebolusing.

I haven't tested blood ketones since I'm clearly not in DKA and my blood sugar is excellent.

I was told, at diagnosis, to test for ketones when I peed if I'd had two readings over 240, one reading over 300, or was sick, or if the previous test had not been negative. I stopped testing ketones for blood sugars over 240 pretty quickly because they were always negative. I tested after blood sugars over 300 since I rarely had blood sugars over 300, but those were also always negative. Even as the high blood sugars became more common, I never got high blood sugar ketones. I would get positive ketones if I vomited, but not for any other illness.

Last summer I tested my ketones after a high blood sugar and found small urine ketones. The high came down and the next day I tested ketones to reassure myself- but they were positive. They took days to come down. That was a different vial of strips.
Since then, I've been testing urine ketones more often and I keep finding results of trace-small (except when ill or fasting- I got large ketones on Yom Kippur and also when I threw up in December).
When I got a blood ketone monitor a few months ago, I had one slightly elevated reading that matched the urine ketone reading, and I had one normal reading at the same time as a large urine ketone reading.

My doctor points out that urine ketones often take longer to go back to normal than blood ketones do. And indeed, after my diagnosis in DKA, my urine ketones took almost two weeks to normalize. But I remain puzzled.


Vera said...

Yes, ketones are weird, I made the same experience. I learnd to ignore them as longs as they are only traces/small - it could always be within the errorrange of the strips. Also, you can have ketones from "fasting" during a goodnight's sleep.

Reyna said...

I hate urine ketone strips due to their inaccuracy and that you cannot just get a sample when you need one (this is hard in a young child).

I am a blood ketone girl all the way. In young children they almost always run ketotic over night...just from fasting over the previous 10 to 12 hours. When Joe was three he would ALWAYS have mod ketones in the am... with normal BGs. That most likely helps to explain the EXTREME insulin resistance that we have been met with at breakfast. It has eased up a bit as he has aged.

Great post. Can you tell I am passionate about blood ketone monitors? :)

Jonah said...

But these were all EVENING ketone tests!