Apparent Loss of Urinary Albumin during Long-term Frozen Storage: HPLC vs

nephelometry is decreased by 30 % in samples that have been frozen at 20 °C. An HPLC method for assessment of urinary albumin that detects immunore-active and immunochemically nonreactive albumin has been introduced as an alternative to immunonephelom-etry. We investigated whether this technique is affected by sample temperature, particularly freezing. Methods: Urine samples (n 295) were collected from the general population (Prevention of Renal and Vascu-lar End-Stage Disease Study). Samples were assessed by both immunonephelometry and HPLC when fresh and after storage at 20 °C for 4, 8, and 12 months and at 80 °C for 12 months. Results: With immunonephelometry, storage for 4, 8, and 12 months at 20 °C resulted in mean (SD) urin