In an attempt to detect patients at high risk of developing diabetic nephropathy, a longitudinal study of urinary albumin excretion rate (radial immunodiffusion) was carried out in 15 female and 8 male long-term insulin-dependent diabetics without proteinuria (negative Albustix test).
Five females and 3 males had an elevated urinary albumin excretion at the time of screening, mean 115 ± 26 (sd) mg/24 h. Our upper normal range for urinary albumin excretion is ≤ 40 mg/24 h. The 5 patients with the highest albumin excretion subsequently developed persistent albuminuria, 132 → 1007 mg/24 h, P < 0.05, elevated serum creatinine, 83 → 128 μmol/l, P < 0.05, and raised blood pressure, 135/86 → 163/112 mmHg, P < 0.05. One patient developed intermittent albuminuria (positive Albustix test), while the variables in the remaining 2 patients were about the same during the 6 years observation period. Fifteen patients had a normal urinary albumin excretion, mean 17 ± 9 (sd) mg/24 h, at the time of the screening. Intermittent and persistent albuminuria developed in 2 patients, while albumin excretion, serum creatinine, and blood pressure were nearly unchanged in the remaining 13 patients after 6 years.
Our longitudinal study indicates that early detection of patients at high and low risk of developing persistent proteinuria i.e. diabetic nephropathy, is possible by using a sensitive method for measuring urinary albumin excretion.