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Test ID: TLCU Immunoglobulin Total Light Chains, Urine

Reporting Name

Immunoglobulin Total Light Chains,U

Useful For

Monitoring patients whose urine demonstrates large M-spikes


Confirming the quantitation of specimens that show M-spikes by electrophoresis


Detecting urine monoclonal proteins and identification of specimens that need urine protein electrophoresis

Clinical Information

Immunoglobulin light chains are usually cleared from blood through the renal glomeruli and reabsorbed in the proximal tubules so that urine light-chain concentrations are very low or undetectable. The production of large amounts of monoclonal light chains, however, can overwhelm this reabsorption mechanism. The detection of monoclonal light chains in the urine (Bence Jones proteinuria) has been used as a diagnostic marker for multiple myeloma since the report by Dr. H. Bence Jones in 1847.


Current laboratory procedures employ protein electrophoresis and immunofixation for the identification and characterization of urine monoclonal light chains, and the monoclonal light chains may be present in large enough amounts to also be quantitated as an M-spike on protein electrophoresis. The electrophoretic M-spike is the recommended method of monitoring monoclonal gammopathies such as multiple myeloma. Monitoring the urine M-spike is especially useful in patients with light-chain multiple myeloma in whom the serum M-spike is very small or absent, but the urine M-spike is large.


Just as quantitative serum immunoglobulins by immunonephelometry are a complement to M-spike quantitation by serum electrophoresis, this quantitative urine light-chain assay may be used to complement urine M-spike quantitation by electrophoresis.


A kappa/lambda (K/L) ratio greater than 6.2 suggests the presence of monoclonal kappa light chains.


A K/L ratio less than 0.7 suggests the presence of monoclonal lambda light chains.


In 24-hour specimens, a greater than 90% increase in concentration suggests progression or relapse; a greater than 90% decrease suggests treatment response.


Increased kappa and/or lambda light chains may be seen in benign (polyclonal) and neoplastic (monoclonal) disorders.

Profile Information

Test ID Reporting Name Available Separately Always Performed
KTLCU Kappa Total Light Chain, U No Yes
LTLCU Lambda Total Light Chain, U No Yes
KLTRU Kappa/Lambda TLC Ratio, U No Yes

Report Available

Same day/1 to 3 days

Day(s) Performed

Monday through Friday

Clinical Reference

1. International Myeloma Working Group. Criteria for the classification of monoclonal gammopathies, multiple myeloma and related disorders: a report of the International Myeloma Working Group. Br J Haematol 2003;121:749-757

2. Rajkumar SV, Kyle RA: Multiple myeloma diagnosis and treatment. Mayo Clin Proc 2005;80(10):1371-1382

3. Snyder MR, Clark R, Bryant SC, Katzmann JA: Quantitation of urinary light chains. Clin Chem 2008;54(10):1744-1746

Method Name

KTLCU, LTLCU: Nephelometry

Specimen Type


Specimen Required

If serum is being submitted on the same patient for FLCP / Immunoglobulin Free Light Chains, Serum; order that test under a different order.


Submit only 1 of the following specimens:


Specimen Type: Random urine

Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 1 mL

Collection Instructions: Collect a random urine specimen.


Specimen Type: 24-Hour urine

Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 1 mL

Collection Instructions: Collect urine for 24 hours.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 7 days
  Frozen  20 days
  Ambient  72 hours

Reference Values


<0.9 mg/dL



<0.7 mg/dL




Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

83883 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TLCU Immunoglobulin Total Light Chains,U 44792-0


Result ID Test Result Name Result LOINC Value
KLTRU Kappa/Lambda TLC Ratio, U 33559-6
KTLCU Kappa Total Light Chain, U 27365-6
LTLCU Lambda Total Light Chain, U 27394-6

Urine Preservative Collection Options

Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.


OK <72 hours





50% Acetic Acid


Boric Acid


Diazolidinyl Urea


6M Hydrochloric Acid


6M Nitric Acid


Sodium Carbonate






Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-Demyelinating-Diseases, mml-Neuroimmunology, mml-Neuromuscular, mml-Autonomic, mml-Pediatric, mml-Spinal-Cord