Beta2-glycoprotein-1 (apolipoprotein H) excretion in chronic renal tubular disorders: Comparison with other protein markers of tubular malfunction

Abstract

Urinary β2-glycoprotein-1 was measured in 60 patients with conditions recognised as causing renal tubular impairment and compared with established markers of early tubular malfunction. Increased β2-glycoprotein-1 excretion was found in 49 (82%) of the subjects; raised excretion of α1-microglobulin, retinol-binding protein, and β2-microglobulin was found in 46 (77%), 45 (75%), and 31 (52%), respectively, and increased urinary N-acetyl-β-D-glucosaminidase activity in 32 of 54 of the subjects (59%). The increase was particularly pronounced in those with proximal tubule malfunction, although considerable variation occurred. β2-glycoprotein-1 was shown to be stable in urine over the physiological pH range, and it is concluded that its measurement provides a means of detecting chronic malfunction of the renal tubules that is marginally more sensitive than assays of α1-microglobulin or retinol-binding protein, and more reliable than assays of β2-microglobulin or N-acetyl-β-D-glucosaminidase.