July 7, 2001
Question from Ypsilanti, Michigan, USA:
My 13 year old daughter has had type 1 diabetes for five and a half years, and since she hit puberty, her A1c’s have averaged around 7%. She has no hypertension and does not smoke. She had a microalbumin/creatine ratio of 268 when taken randomly at the office, we then submitted a first morning urine that came out at 28. My question regards the new normal cutoff, I understand it used to be 10 and now it’s 30. Is my daughter’s still high even though it is in the “normal” range? Could someone without diabetes have a ratio that high? They are not putting her on an ace inhibitor, but are her kidneys starting to be affected by her diabetes, and is she more at risk for kidney disease later?
Congratulations to you and your family and your daughter for keeping her HbA1c in the 7% range. Different methods for measuring HbA1c have differing normal ranges, but by most accounts, HbA1c values in the 7% range suggest good diabetes control.
And in and of itself, this would make diabetes-related kidney disease (“diabetic nephropathy”) less likely. A number of factors can contribute to “spilling” a small amount of protein into the urine including such common, temporary situations as a viral infection, a urinary tract infection, vaginal discharge, recent exercise, and in some patients, simply “moving around a lot or changing positions” leading to changes in blood pressure flow. This is sometimes called “orthostatic proteinuria.” That is why a random, one-time measurement of urine microalbumin (microscopic amounts of albumin) do not equate with diabetic nephropathy.
It sometimes gets confusing, even to health care professionals, as to the “number” assigned to indicate more significant microalbumin excretion. There are a number of ways to express this. One way is the ratio of microalbumin relative to the amount of a urine waste-product called creatinine. The value that most use to indicate significant microalbumin is more than 30 micrograms per milligram of creatinine in a random, one-time “spot” collection of urine. The other, perhaps more sensitive, method involves carefully collecting urine over a specific period of time and measuring the amount of microscopic albumin (“microalbumin”) relative to time. Normal values will be expressed as less than 20 micrograms per minute (or in a complete 24 hour day, less than 30 milligrams per 24 hours.) We have to be careful to note the units of measurement: micrograms vs milligrams. The numbers can “look different” even though they measure similar things: (for example, 55 miles per hour is the same as about 90 kilometers per hour.)
It does not sound as if you were instructed to provide a 24 hour urine collection. So if your daughter’s value of “28” was actually 28 micrograms per minute, on a timed overnight sample, I would find that slightly high. I’d suggest that it be repeated to confirm, and if verified, she might warrant being placed on an ACE inhibitor, which modifies the blood flow through the kidneys. If her value of “28” is actually 28 micrograms per milligram of creatinine, then it remains in the normal range and probably should just be repeated in 6-12 months, per the routine of your Diabetes Team.