Saudi Journal of Kidney Diseases and Transplantation

LETTER TO THE EDITOR
Year
: 2010  |  Volume : 21  |  Issue : 5  |  Page : 949--950

Protein-to-creatinine ratio: A valid estimate and alternative to 24 hour proteinuria


Ayman Karkar, Mohammed Abdelrahman 
 Department of Nephrology, Kanoo Kidney Centre, Dammam Medical Complex, P.O. Box 11825, Dammam 31463, Saudi Arabia

Correspondence Address:
Ayman Karkar
Department of Nephrology, Kanoo Kidney Centre, Dammam Medical Complex, P.O. Box 11825, Dammam 31463
Saudi Arabia




How to cite this article:
Karkar A, Abdelrahman M. Protein-to-creatinine ratio: A valid estimate and alternative to 24 hour proteinuria.Saudi J Kidney Dis Transpl 2010;21:949-950


How to cite this URL:
Karkar A, Abdelrahman M. Protein-to-creatinine ratio: A valid estimate and alternative to 24 hour proteinuria. Saudi J Kidney Dis Transpl [serial online] 2010 [cited 2021 Mar 9 ];21:949-950
Available from: https://www.sjkdt.org/text.asp?2010/21/5/949/68900


Full Text

To the Editor,

The 24 hour urine collection test has been the gold standard method of assessing urinary pro­tein excretion in patients with nephrotic syn­drome and chronic kidney disease. It is used extensively for diagnostic and prognostic pur­poses and to assess the effects of therapy. This test is usually performed in a hospital labora­tory and requires clear instructions to patients or their companions and supplementation of pa­tients with a graduated plastic container. How­ever, there are limitations to the performance of this test. These include (1) the amount of pro­tein excretion is a function of urine volume; (2) adequate collection must be ensured; (3) it is cumbersome for patients and not many of them clearly understand or stick to the given instruc­tions; (4) it is time consuming and not always accurate; (5) lack of its availability in health centers and occasionally in hospital laboratories and (6) may constitute a huge burden on labo­ratories workload. In 1983 Ginsberg et al [1] esta­blished a quick test of single voided urine sam­ple to estimate quantitative proteinuria. In a study of 46 specimens they found an excellent correlation between the protein content of 24­hour urine collection and the protein/creatinine ratio in a single urine sample. The best corre­lation was found when samples were collected after the first voided morning specimen and be­fore bedtime. They concluded that in the pre­sence of stable renal function, a protein/crea­tinine ratio of more than 3.5 (mg/mg) can be taken to represent "nephrotic-range" proteinu­ria, and a ratio of less than 0.2 is within normal limits. This protein/creatinine ratio test on ran­dom urine samples has been recommended by the National Kidney Foundation-K/DOQI guide­ lines. [2]

In our daily practice, we faced the above men­tioned difficulties in assessing proteinuria by 24-hour urine collection. These reasons and the need to repeat measurements for a successful clinical management prompted us to evaluate the reliability of the urine protein/creatinine ratio as a replacement of the 24-hour urine collection for measurement of proteinuria. We investigated 150 patients with proteinuria due to variable causes of chronic kidney disease including diabetic nephropathy, glomeruloneph­ritis and nephrotic syndrome who were on re­gular follow up in outpatient nephrology clinic. Only 116 patients (77%) were able to fulfill the instructions of urine collection. The mean age of these patients was 52 ± 13 years and there were 60 males and 56 females. Patients were requested to provide 24-hour urine collection and a random morning urine sample for protei­nuria and protein/creatinine ratio measurements. The mean daily protein excretion was 2.168 ± 3.089 gm/24 hour and the mean protein/crea­tinine ratio was 2.171 ± 2.719 mg/mg. There was a strong and significant positive correlation between the 24-hour urine total protein excre­tion and the spot urine protein/creatinine ratio (r= 0.942, P< 0.0001, MedCalc statistical soft­ware version 10.4) as shown in the [Figure 1]. However, there might be a lower agreement between the 24-hour proteinuria and the pro­tein/creatinine ratio for higher levels of pro­teinuria. In conclusion, these results confirm the early findings of Ginsberg et al 1 and are con­sistent with similar recently published studies, [3],[4],[5] where random spot urine analysis for pro­tein/creatinine ratio could be a reliable and con­venient method that may replace the proteinuria assessment by 24-hour urine collection.{Figure 1}

References

1Ginsberg JM, Chang BS, Matarese RA, Garella S. Use of single voided urine samples to estimate quantitative proteinuria. N Engl J Med 1983; 309:1543-6.
2Keane WF, Eknoyan G. Proteinuria, albuminuria, risk, assessment, detection, elimination (PARADE): A position paper of the National Kidney Foundation. Am J Kidney Dis 1999;33:1004-10.
3Wahbeh AM, Ewais MH, Elsharif ME. Com­parison of 24-hour urinary protein and protein­to-creatinine ratio in the assessment of protei­nuria. Saudi J Kidney Dis Transpl 2009;20(3): 443-7.
4Antunes VV, Veronese FJ, Morales JV. Diag­nostic accuracy of the protein/creatinine ratio in urine samples to estimate 24-H proteinuria in patients with primary glomerulopathies: a longi­tudinal study. Nephrol Dial Transplant 2008;23: 2242-6.
5Rodriguez-Thompson D, Lieberman ES. Use of a random urinary protein-to-creatinine ratio for the diagnosis of significant proteinuria during pregnancy. Am J Obstet Gynecol 2001;185:808­11.