Correlation Between the Urinary Protein/Creatinine Ratio in a Single Urine Sample Versus 24-hour Proteinuria in Patients With Multiple Myeloma.
The measure of 24-hour proteinuria is an important biomarker for multiple myeloma.
Multiple myeloma is often accompanied by proteinuria overhead of secretion by plasma cells
of large quantities of immunoglobulin free light chains (FLC) kappa or lambda. This
proteinuria is composed of monoclonal FLC. The measure of the urinary concentration of FLC
is an important biomarker for both diagnosis and evaluation of response to treatment of
light chain multiple myeloma but also in intact immunoglobulins multiple myeloma.
The 24-hour proteinuria coupled with urine protein electrophoresis is the standard method
for measuring the concentration of urinary FLC. However, it is difficult to obtain a
reliable collection of the urine of 24 hours which can make it difficult to assess response
to therapy in some patients. It would be interesting to assess proteinuria in a single urine
sample collected at any time of day.
Contribution of urinary protein/creatinine ratio for assessment of proteinuria of glomerular
For reasons of convenience, the extent of 24-hour proteinuria was increasingly abandoned by
nephrologists in favor of urinary protein/creatinine ratio (UPCR). The use of UPCR measured
on a sample of urine overcomes the inaccuracies related to the collection of 24 or
variations in urine concentration. This report has been validated against the 24-hour
proteinuria for screening or monitoring of renal glomerular diseases by the French Society
of Nephrology. In theory, the UPCR is measured on a urine sample, taken preferably in the
morning. In practice, the precision of a measurement at any time of day is quite acceptable.
Using the urinary protein/creatinine ratio for assessment of response in multiple myeloma?
The use of UPCR has been validated in patients with renal glomerular disease and especially
in diabetic nephropathy. However, the UPCR has not been validated for the assessment of
proteinuria overload such as those seen in myeloma. Two recent papers have studied the UPCR
in multiple myeloma. The results of these articles suggest:
- That the UPCR is well correlated with the 24-hour proteinuria
- The UPCR varies over time depending on the response to treatment and could therefore be
used to monitor patients on treatment
However, given their limits, these two articles do not alow to recommend the widespread use
of UPCR instead of the classic 24-hour proteinuria in clinical practice yet. Prospective
studies are needed to analyze the correlation between UPCR and proteinuria of 24 hours to
assess response to therapy.
Time Perspective: Prospective
change in urinary protein/creatinine ratio
To study the correlation between the urinary protein/creatinine ratio in the sample and 24-hour proteinuria in the assessment of treatment response in patients with multiple myeloma.
Change from baseline in urinary protein/creatinine ratio at 8 AM, 12 AM, 4 PM
Olivier DECAUX, MD
Service de Medecine interne - Hôpital Sud - Rennes
France: The Commission nationale de l’informatique et des libertés