Objective: To evaluate the stability of microalbuminuria figures in urine samples of diabetic patients, in terms of how the samples are kept, and the time between taking and reading.
Design: Descriptive, prospective and observational study.
Setting: Primary care. Teaching health centre, Burgos.
Patients: 40 type-2 diabetics had their urinary excretion of albumin measured in 91 first-in-the-morning urine samples with Micral Test II reactive strips.
Interventions: Samples were analysed the day of their collection, then protected from light and kept at +4 degrees C, with further readings at 24, 48 and 72 hours and at 7, 14, 21 and 28 days after collection.
Measurements and main results: 49 (53.84%) of the 91 samples taken did not vary over the 28 days of the study. In the first three days, there were 64 with unvaried measurements (70.2%). Friedman's test showed p = 0.905. > 93% of samples positive at the beginning remained positive all the time; > 83% of samples negative at the beginning remained negative. Concordance observed was > 90%; kappa index > 80%.
Conclusions: Collection of first urine samples in the morning, stored at +4 degrees C in a fridge and protected from light, did not significantly alter the result of the reading for 4 weeks. Such samples are useful in order to aid study of the albumin excretion rate using Micral Test II reactive strips.