A prospective study of protein excretion using short-interval timed urine collections in patients with lupus nephritis

Derek M. Fine, Martina Ziegenbein, Michelle Petri, Ernest C. Han, Alison M. McKinley, Jerry W. Chellini, Haikady N. Nagaraja, Kathryn A. Carson, Brad H. Rovin

Research output: Contribution to journalArticle

Abstract

The 24-h urine protein-to-creatinine ratio is the gold standard in evaluating proteinuria in lupus nephritis; however, the urine collection is inconvenient to the patient. Random spot urine protein-to-creatinine ratios, although convenient, have poor agreement with the 24-h ratios in these patients. Here, we sought to define a timed collection interval providing accurate and precise data and patient convenience. Urine from 41 patients, in 2 medical centers, with biopsy-proven lupus nephritis was collected at 6-h intervals for 24 h. The protein-to-creatinine ratio of each short collection was then compared with that of a 24-h collection made by combining the 6-h samples. A first morning void and spot urine samples were collected before and after the 24-h collection, respectively. There was significant diurnal variation with peak proteinuria at 6-12 h and nadir at 18-24 h. Each 6-h collection showed excellent correlation and concordance with the 24-h protein-to-creatinine ratio, but the 12-24-h interval had the best agreement. In contrast to the random spot urines, the first morning void also had excellent correlation and concordance, but underestimated the 24-h protein-to-creatinine ratio. Our study shows that a 12-h overnight urine collection is the best surrogate, with excellent agreement with the 24-h protein-to-creatinine ratio, and it is convenient for patients. There was little variability between centers, an important feature for clinical trials.

Original languageEnglish (US)
Pages (from-to)1284-1288
Number of pages5
JournalKidney International
Volume76
Issue number12
DOIs
StatePublished - Dec 1 2009

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Keywords

  • Glomerulonephritis
  • Lupus nephritis
  • Nephritis
  • Proteinuria systemic lupus erythematosus

ASJC Scopus subject areas

  • Nephrology

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