June 24, 2006
Diagnosis and Symptoms, Other
Question from Boston, Massachusetts, USA:
My five year old daughter was sent to the Emergency Room (ER) twice last year, two months apart, because she had glucose and ketones in her urine during viral illnesses. She had increased urination so I had thought she might have an UTI. Her highest blood sugar at the doctor was 168 mg/dl [9.3 mmol/L], but went down by the time we got to the ER. She was later seen by an excellent pediatric endocrinologist and all tests were normal/negative with an A1c of 5.5. I was told that the laboratory they used, Joslin’s, had a false-negative antibody rate as low as 5%. We were told she had simple stress hyperglycemia, thankfully.
When your web site states that only approximately 80% of kids with type 1 will have positive antibodies, is it (1) a child with type 1 can still have negative antibodies 20% of the time or (2) that the laboratory will not be able to determine positive antibodies 20% of the time?
When I picked my daughter up from school today, there was a note that she urinated three times in 45 minutes. I used some urine test strips for glucose and it was negative. I have never checked her blood sugar as her urine tests are always negative (except the one time she was sick this year). The glucose was negative, but she had large (4+) ketones. Her pediatrician said this was normal if a child is vomiting or not eating. If a child is constantly urinating due to hyperglycemia, could the glucose be continually flushed out or would the test always be positive? I ask these questions because I would like to completely rule out hyperglycemia as the cause of her frequent urination. I’m thinking that since a year has gone by, we’re pretty lucky and she probably just has a small bladder. A test for diabetes insipidus was negative.
Answer:
It is possible to have type 1 diabetes and negative antibodies for reasons that we do not understand. If the tests were done at a reputable laboratory, and Joslin’s laboratory is certainly excellent, this is the data that you have. Negative tests are not so helpful since they do not distinguish the 20% negatives from true negatives for this diagnosis. Positive tests that are persistent are more important, of course. Ketones only represent fat utilization and, associated with low sugars, suggest that there is inadequate energy provided. High sugars and high ketones are more worrisome since this may represent insulin deficiency and thus diabetes.
The excess urination is puzzling and unlikely related to hyperglycemia since you have no positive sugars in the urine and none in the blood during these episodes. High blood sugars are filtered and present in the urine and the high sugars “drag” water and electrolytes (salts) with them thus causing the excess urination. So, there is no flushing out to consider since the hyperglycemia is the primary culprit.
You should stay in contact with your pediatrician and also the consulting endocrinologist particularly if these symptoms persist, if there is continued abnormalities of ketones or blood/urine sugars for repeat testing and advice.
SB
