sFLC, the logical means of identifying monoclonal FLC in

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					sFLC, the logical means of identifying
monoclonal FLC in the event of poor
urine sample provision?


Dr Tracy J Lovatt
Clinical Scientist, Immunology
New Cross Hospital
tracy.lovatt@rwh-tr.nhs.uk
Traditional screening for LPD
   Measure IgG, IgA, IgM

   Serum protein or capillary zone
    electrophoresis

   Immunofixation of abnormal bands

   Urine electrophoresis and immunofixation
    for BJP.
Urine electrophoresis
Urine Immunofix
    Renal Metabolism of FLC
                   FLC - 25 kDa
                   FLC - 50 kDa

   Glomerulus                      1.   Renal metabolism
 40-60 kDa pores
                                   2.   Anuric
                                   3.   Provision
                                   4.   Smell
 10-30g/day
reabsorption
& breakdown




                    Urine
Serum free light chain immunoassay


                                       exposed surface
        exposed surface        Kappa

             hidden surface




                                                 Previously
                                                hidden surface
heavy
chain

                              Lambda
    light chain
Aim


   To determine whether sFLC could
    replace urine electrophoresis when
    screening for myeloma and other
    plasma cell dyscrasia?

   Calculate sensitivity/specificity for
    LPD
     Results n=653


   597 normal by SPE and FLC         (91%)

   17 clear band and abnormal FLC   (2.6%)

   21 paraprotein but normal FLC     (3.2%)

   18 no band on SPE but abnormal FLC (2.5%)
        Performance

                 Test/Diagnosis            Performance


            +/+ -/- -/+ +/-            Sensitivity   Specificity
FLC >1.84    26 609  9  9               74.3          98.5

SPE         23   602      12      16    65.7          97.4

SPE & FLC   35   597      0       21    100.0         96.6
>1.84
Results……

   30/653 had urine sample (4.6%)

       1/30 positive for BJP (amyloidosis)

       Dodgy ground?
Obvious?


 For laboratories receiving <5%
 urine samples arguing the relative
 merits of sFLC and urine BJP
 borders on the irrelevant.
What’s the cost?
 Write to patient

 Return visit to hospital or GP

 Admin and cost of BJP and report

 Patient anxiety
   Normal range for sFLC ratio


  0.26 - 1.65 – Published reference range

  0.25 – 1.84 – Local reference range NX


8 results
1.65 – 1.84 (Crohn’s, RA, SLE, PMR)
Normal SPE/ Abnormal FLC
   12 /18 Lymphoproliferative Disorders

       1 IgD Myeloma

       1 IgA Myeloma/MGUS

       6 CLL (1 undiagnosed at the time of screening)

       4 FLC-MGUS


   6/18 no LPD (0.2; 0.22; 0.25; 1.92;
    1.97; 2.0)
Case 1 – IgD Myeloma

Case 1


         •SPE - no obvious paraprotein

         •Insufficient evidence to initiate IF

         •Serum Free Light Chain Analysis:

                 Kappa = 27.8mg/L

                 Lambda = 868mg/L

                 Kappa/Lambda Ratio = 0.003
Case 1: IgD Myeloma



              •IFE demonstrated the presence of
              an IgD Lambda paraprotein

              •Patient referred to Haematologist

              •Follow-up Investigations
              confirmed myeloma

              •Patient refused follow up
Case 2
     73 yr old female
         Seen by GP with “mobility issues”


     Lab Results
         IgG 10.3(g/L)
         IgA 4.29 (g/L)
         IgM 1.1 (g/L)
IgA paraprotein
Case 2



         •SPE - no obvious paraprotein

         •Insufficient evidence to initiate IFE

         •Serum Free Light Chain Analysis:

                 Kappa = 72.8mg/L

                 Lambda = 14.6mg/L

                 Kappa/Lambda Ratio = 4.99
Case 2: IgA Myeloma/MGUS


                 •IFE demonstrated IgA kappa
                 band

                 •Hidden in Beta Region on SPE

                 •Since initial sample patient has
                 had mild deterioration in renal
                 function

                 •No significant change in
                 patients condition

                 •Patient under evaluation to
                 determine IgA Myeloma/MGUS
Freelite
Another case
   69 yrs, female
   Presented Jan 2008
   Lambda light chains on SPE/IF
   Fast track referral
   Light chain myeloma
   sFLC

Kappa 9.2 mg/L
Lambda 33 mg/L
Ratio  0.28 (0.25 – 1.84)
Antigen Excess
   Default dilution 1/100
   Retest at 1/2000

Kappa 9.2 mg/L
Lambda 7779 mg/L
Ratio  0.001

Normal range (0.25 – 1.84)
October 2008

   Dilution 1/2000

Kappa 10.2 mg/L
Lambda 67.2 mg/L
Ratio  0.15

Normal range (0.25 – 1.84)
30th March 2009
   Clinic
   Unwell
   Admitted ? relapse


Kappa 6.17 mg/L
Lambda 77.9 mg/L
Ratio  0.08
1st April 2009
   Question results
   Retest at 1/2000

Kappa 6.17 mg/L
Lambda 36432 mg/L
Ratio  0.0001

Rapid disease progression
Aggressive

Date         Lambda mg/L

17.04.09     29,000

24.04.09     23,000

05.05.09     18,650
 Recommendations
Useful to establish local reference
range for sFLC

Addition of sFLC to primary screen for
paraproteinemia increases the
sensitivity and improves specificity for
LPD.

Not for all Immunoglobulin requests
Recommendations


 With poor urine provision it seems
 logical to add sFLC rather than
 request a urine sample.

 Check for antigen excess at 1/2000

 Antigen excess is patient specific
Acknowledgements

   Ewan Robson, Claire Beardsmore,
    Joanne Taylor, Liz Laverick,
    Stephanie Cooper

The Binding Site Ltd
Graham Mead and Josie Hobbs.