Interpretive Handbook

Test 84448 :
Alpha-1-Microglobulin, Random, Urine




Elevated excretion rates can indicate tubular damage associated with renal tubulointerstitial nephritis or tubular toxicity from heavy metal or nephrotoxic drug exposure. Glomerulonephropathies and renal vasculopathies also are often associated with coexisting tubular injury and so may result in elevated urinary alpha-1-microglobulin excretion. Elevated alpha-1-microglobulin in patients with urinary tract infections may indicate renal involvement (pyelonephritis). Measurement of urinary excretion of retinol-binding protein, another low-molecular-weight protein, is an alternative to the measurement of alpha-1-microglobulin. To date, there are no convincing studies to indicate that 1 test has better clinical utility than the other.




Assessment of renal tubular injury or dysfunction


Screening for tubular abnormalities


Detecting chronic asymptomatic renal tubular dysfunction

Interpretation Provides information to assist in interpretation of the test results

Alpha-1-microglobulin above the reference values may indicate a proximal tubular dysfunction. As suggested in the literature, 7 mg/g creatinine is an upper reference limit for pediatric patients of 1 month to 15 years of age.


Since this is a nephelometric assay, turbidity and particles (eg, cells, crystals) in the sample can interfere with the test. Therefore, all urine specimens should be centrifuged at ambient temperature prior to assay.


<50 years: <13 mg/g creatinine

> or =50 years: <20 mg/g creatinine


1. Akerstrom B, Logdberg L, Berggard T, et al: Alpha-1-microglobulin: a yellow-brown lipocalin. Biochimica et Biophysica Acta 2000 Oct 18;1482(1-2):172-184

2. Hjorth L, Helin I, Grubb A: Age-related reference limits for urine levels of albumin, orosomucoid, immunoglobulin G and protein HC in children. Scand J Clin Lab Invest 2000 Feb;60(1):65-73
