My one year old daughter, who weighs about 16 pounds, was diagnosed with VUR at three months of age and has been diagnosed as FTT (Failure to thrive). They did the diabetes test which was negative, but she had urine reducing substances so they ran additional tests.

The tests finally showed she has fructose overflow in her urine, and I have been mixing powdered formula with fruit juice. This would be okay except for the fact that when they went back and looked at tests when she was three months old, her urine tested positive for reducing substances then too, and there is no way it could be fructose because she was solely breast fed back then.

My understanding is that diabetes can be difficult to diagnose. How likely is it to have a negative test but still have diabetes?

Assuming that VUR stands for vesicu-ureteral reflux, which I don’t think would have anything to do with the ‘failure to thrive’ unless there were repeated urinary tract infections. The doctors were clearly trying to explain this failure to thrive in terms of an inborn error of metabolism, and, since they found abnormal amounts of fructose in the urine that certainly would suggest hereditary fructose intolerance which is an autosomally recessive condition treated by a fructose free diet.

If this diagnosis has now been confirmed, it is still difficult to explain the urine fructose at three months of age unless you were giving supplements that contained ordinary cane sugar, which is equal parts of glucose and fructose or you yourself were taking sugar in your diet which would lead to fructose in the breast milk. Her weight and food intake are below the third percentile for her age which suggests the possibility of some other explanation or possibly that she is getting cane sugar in some medication or vitamin supplement.

Another possibility to discuss with the doctor is that an undetected urinary tract infection is leading to hypoglycemia and lactic acidosis.

Finally, I should add that I don’t think that your baby has any form of diabetes.

DOB
Additional comments from Dr. David Schwartz:

A “reducing substance” commonly refers to any component in urine that, when mixed with a copper derivative (called cupric sulfate), leads to a change in color of the urine, generally a blue color. Typical “reducing substances” include various types of sugar such as glucose, galactose (milk sugar), fructose (fruit sugar), lactose (a mixture of glucose and galactose), and other sugars (but not table sugar (sucrose). However, other reducing substances include a large list compounds including a variety of drugs and other antibiotics.

Therefore, the presence of reducing substances in the urine is by no means specific for glucose in the urine, and one cannot establish a diagnosis of diabetes by this test. If reducing substances are present in the urine, but further analysis indicates that there is not glucose in the urine and that the blood glucose is normal, then diabetes is pretty much excluded. Then however. one must try to determine the cause of the presence of reducing substances. In a child who is failing to thrive, eats so little, at one year of age weighs 15 pounds, and at present, the “only” reducing substance seems to be an excess of fructose in the urine. Then I think there may be an issue in the proper metabolism of fructose. There are other possibilities and some, frankly, may be worrisome.

Please ask for a referral to specialist in “inborn errors of metabolism.” This may be a pediatric endocrinologist but more commonly is a specially trained geneticist who likely will be located at a major medical university or children’s hospital in your region.

DS