Usefulness of HPLC Assay for Early Detection of Microalbuminuria in Chronic Kidney Disease

Abstract

Since the degree and increase of albuminuria predict cardiovascular and renal diseases even within the range of normoalbuminuria. The high-performance liquid chromatography (HPLC) assay has been reported as a useful tool for earlier detection of microalbuminuria than turbidimetric immunoassay (TIA) in diabetes but has not been evaluated for other common diseases that caused chronic kidney disease (CKD). We measured albumin in spot urine by TIA and HPLC assay in 119 patients with diabetes, hypertension, IgA nephropathy in complete remission, or autosomal-dominant polycystic kidney disease whose dipstick screening tests were negative. There were significant correlations (r = 0.946) between TIA and HPLC assay, and the ratios of urine albumin/creatinine (ACR) measured by HPLC assay were always higher than those measured by TIA. The value of microalbuminuria was highest in IgA nephropathy patients, and higher in diabetic patients with hypertension than in those without hypertension. Fifty-one patients were classified as having normoalbuminuria and 42 as having microalbuminuria by both TIA and HPLC assay. However, 26 patients (21.8%) were classified having as normoalbuminuria by TIA but microalbumnuria by HPLC assay. Three of these patients were reclassified as microalbuminuria by both assays within 1 year. These results suggest that ACR measurements by HPLC assay are better than TIA for early detection and monitoring of microalbuminuria in patients with diabetes and hypertension.