Increased albumin excretion rate during a standardized exercise-test in diabetics with lowered blood filterability

Albumin excretion rate in urine is a marker of early, reversible stages of diabetic nephropathy. Does abnormal blood rheology represent an additional risk factor in this multifactorial process? We investigated a possible link between red cell filterability and microalbuminuria during an exercise test (exercise is supposed to improve the detection of excessive microalbuminuria). 77 diabetics (27 females, 50 males, age: 15-60 yr) underwent a 20 min inframaximal progressively increasing workload on cycloergometer, rising heart rate up to 200 minus the age. Filterability of whole blood and washed red cells were measured on 5 microns polycarbonate sieves reused after ultrasonic cleaning. Whole blood filterability was found to be impaired in 35 subjects (group A) and normal in 41 (group B). Groups A and B were matched for age, sex, blood pressure, glycemic equilibrium, and duration of disease. Microalbuminuria was higher in A at rest (39.79 +/- 13.83 micrograms/min vs 12.9 +/- 3.21, p less than 0.01) and after exercise (91.80 +/- 20.79 vs 42.23 +/- 7.85, p less than 0.01). The slopes of regression lines between resting Microalbuminuria and blood pressure were greater in group A than in group B (p less than 0.01). No relationship between microalbuminuria and washed red cell filterability was detected. This study confirms on a larger scale a previous report of our team. Some hemorheologic disorders detectable with whole blood filterability (but not with washed red cell filtration) are associated with an increase in resting and postexercise microalbuminuria.