NDT Advance Access published online on November 26, 2008
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfn639
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Diagnostic accuracy of a reagent strip for assessing urinary albumin excretion in the general population
1 Laboratorio di Analisi Chimico Cliniche ed Ematologiche, Ospedale Civile Maggiore 2 Dipartimento di Scienze Biomediche e Chirurgiche, Divisione di Nefrologia, Università degli Studi di Verona and Ospedale Civile Maggiore, Azienda Ospedaliera di Verona, Italy
Correspondence and offprint requests to: Maria Stella Graziani, Laboratorio di Analisi Chimico Cliniche ed Ematologiche, Ospedale Civile Maggiore, Azienda Ospedaliera di Verona, piazzale Stefani, 1 37126 Verona, Italy. Tel +39-045-812-2421; Fax: +39-045-812-356; E-mail: mariastella.graziani{at}azosp.vr.it
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Abstract |
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Background. Albuminuria is a sensitive marker of renal derangement and has been included in a number of studies investigating chronic kidney diseases (CKDs). This study is aimed to evaluate the diagnostic performances of a strip for measuring the albumin/creatinine ratio (ACR) in the general population and to compare it with those found in a diabetic population.
Methods. Urine samples were obtained from 201 consecutive subjects enrolled in an epidemiological study and from 259 type 2 diabetic patients. Urine was tested for albumin and creatinine using the strip (Clinitek Microalbumin) and laboratory methods. A hundred samples were stored under various conditions to assess analyte stability.
Results. In the general population, the strip test reached a 90% sensitivity and 91% specificity, considering the laboratory method as the ‘gold standard’, sparing >80% of subjects the laboratory tests at the expense of a 1% false negative rate and an 8% false positive rate. Regarding sensitivity and specificity, the ACR test performs very similarly in the general population and in the diabetics. The stability study showed that storage at –20°C induced a significant decrease in the albumin concentration with both methods, such that 5% of the samples were re-classified in the lower ACR class. Storage at –80°C for up to 12 months did not affect the measurement with both methods.
Conclusion. Clinitek Microalbumin strips can be used for screening purposes in the general population since they correctly classify a significant percentage of subjects, particularly those with a normal albuminuria. Storage at –80°C does not affect strip results. Screening with the strip and confirming positive results with a wet chemistry method are an efficient strategy for detecting albuminuria in the general population.
Keywords: albumin/creatinine ratio; CKD; diabetic nephropathy; dipstick urinalysis; screening
Received for publication: 5. 6.08
Accepted in revised form: 23.10.08