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Cross sectional longitudinal study of spot morning urine protein:creatinine ratio, 24 hour urine protein excretion rate, glomerular filtration rate, and end stage renal failure in chronic renal disease in patients without diabetes

BMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7130.504 (Published 14 February 1998) Cite this as: BMJ 1998;316:504
  1. Piero Ruggenenti, doctor (ruggenenti{at}irfmn.mnegri.it)a,
  2. Flavio Gaspari, chemista,
  3. Annalisa Perna, statistical scientista,
  4. Giuseppe Remuzzi, directora
  1. a Mario Negri Institute for Pharmacological Research, Clinical Research Centre for Rare Diseases, Via Gavazzeni 11, 24125 Bergamo, Italy
  1. Correspondence to: Dr Ruggenenti
  • Accepted 27 November 1997

abstract

Objective: To evaluate whether the protein:creatinine ratio in spot morning urine samples is a reliable indicator of 24 hour urinary protein excretion and predicts the rate of decline of glomerular filtration rate and progression to end stage renal failure in non-diabetic patients with chronic nephropathy.

Design: Cross sectional correlation between the ratio and urinary protein excretion rate. Univariate and multivariate analysis of baseline predictors, including the ratio and 24 hour urinary protein, of decline in glomerular filtration rate and end stage renal failure in the long term.

Setting: Research centre in Italy.

Subjects: 177 non-diabetic outpatients with chronic renal disease screened for participation in the ramipril efficacy in nephropathy study.

Main outcome measures: Rate of decline in filtration rate evaluated by repeated measurements of unlabelled iohexol plasma clearance and rate of progression to renal failure.

Results: Protein:creatinine ratio was significantly correlated with absolute and log transformed 24 hour urinary protein values (P=0.0001 and P<0.0001, respectively.) Ratios also had high predictive value for rate of decline of the glomerular filtration rate (univariate P=0.0003, multivariate P=0.004) and end stage renal failure (P=0.002 and P=0.04). Baseline protein:creatinine ratios and rate of decline of the glomerular filtration rate were also significantly correlated (P<0.0005). In the lowest third of the protein:creatinine ratio (<1.7) there was 3% renal failure compared with 21.2% in the highest third (>2.7) (P<0.05).

Conclusions: Protein:creatinine ratio in spot morning urine samples is a precise indicator of proteinuria and a reliable predictor of progression of disease in non-diabetic patients with chronic nephropathies and represents a simple and inexpensive procedure in establishing severity of renal disease and prognosis.

Key messages

  • The protein:creatinine ratio measured in spot morning urine samples is a simple and reliable indicator of 24 hour urinary protein excretion rate and can therefore be used to quantify proteinuria without the need for timed urine collection

  • Spot morning urinary protein:creatinine ratio is the strongest baseline predictor of progression of renal disease in non-diabetic patients with chronic nephropathies

  • Compared with 24 hour urinary protein excretion rate, the spot morning ratio is an even more reliable predictor of decline in glomerular filtration rate and progression to end stage renal failure and represents a simple and inexpensive procedure in the determination of severity of renal disease and prognosis

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