Int J Pharm Bio Sci 2015 Jan; 6(1): (B) 1074 - 1080

Research Article

Biochemistry

International Journal of Pharma and Bio Sciences

ISSN 0975-6299

SERUM FREE LIGHT CHAIN RATIO IN CORRELATION WITH SERUM PROTEIN ELECTROPHORESIS IN MULTIPLE MYELOMA PATIENTS FROM SOUTH INDIA. DR.NOORJAHAN MOHAMMED*1, DR.S.SUDHA MURTHY2 AND DR. PALANKI SATYA DATTATREYA3. 1

Nizam’s Institute of Medical Sciences, Hyderabad. Basavatarakam Indoamerican Cancer Hospital & Research Institute, Hyderabad. 3 Omega Hospital, Hyderabad 2

ABSTRACT Quantitative measurement of serum free light chains (S.FLC) has now been adopted into screening algorithms for multiple myeloma (MM). The assay indicates monoclonal free light chain production by the presence of abnormal kappa or lambda free light chain ratio (reference range 0.26-1.65). We report our experience with S.FLC assay in patients of MM in correlation with serum protein electrophoresis (SPE). Review of 50 cases of MM was undertaken. MM was diagnosed in these cases, according to the International Myeloma Working Group (IMWG) criteria. S.FLCs were measured by immunoturbidimetry method, SPE was done on cellulose acetate strip. All 50 cases of MM patients showed abnormal ratio of S.FLCs while SPE could detect monoclonal protein in 44(88%) out of 50 cases. The results indicate that serum FLC analyses have high diagnostic sensitivity and are of additional value in the detection of monoclonal proteins where there is strong clinical suspicion, especially when not detected by SPE. KEYWORDS: Multiple Myeloma (MM), Serum Protein Electrophoresis (SPE), Serum Free Light Chains (S.FLC).

*Corresponding author

DR.NOORJAHAN MOHAMMED Nizam’s Institute of Medical Sciences, Hyderabad.

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Int J Pharm Bio Sci 2015 Jan; 6(1): (B) 1074 - 1080

INTRODUCTION Myeloma and multiple myeloma (MM) are referred as cancer of antibody producing plasma cells. Although such a cancerous plasma cell, called myeloma cell has been transformed, its protein synthesizing machinery and secretory functions are not altered, thus, the cell continues to secrete specific antibody. The secreted antibodies are indistinguishable from normal antibody molecules but are called myeloma protein (M-protein, paraprotein) to denote its source. In 99% of the cases, paraproteins are secreted in the serum and/or urine (Bence-Jones protein) and in the remaining 1% the paraproteins are synthesized but not secreted1. The electrophoretic analysis of the serum sample is the first step for observing the altered protein concentrations and the presence of an M peak portion of proteins, which indicates myeloma but not its type1. Quantitation of monoclonal protein (Mprotein) by serum protein electrophoresis (SPE) is recommended as a tumour marker in patients with monoclonal gammopathy. However, SPE is a semiquantitative method for detection of M proteins, and may be misinterpreted as a negative result due to lack of sensitivity, or the masking effect from other proteins when the Mprotein is not present in the gamma fraction. The accuracy of urine protein electrophoresis has been questioned in patients with proteinuria. Moreover, SPE and Immunofixation electrophoresis (IFE) have limited use in the identification of patients with light chain multiple myeloma (LCMM), nonsecretory multiple myeloma (NSMM) and AL amyloidosis where the M-protein may not be present in sufficient concentrations for detection2. However, the standard screening tests for myeloma, serum protein electrophoresis and urine Bence-Jones protein analysis are not always requested or reported promptly3. Quantitative measurement of serum free light chains (FLC) has now been adopted into screening algorithms for multiple myeloma4. International guidelines recommend a primary MM screen of SPE, serum IFE and serum FLC analyses. However, a recent report suggests

this can be simplified to SPE and serum FLCs, with reflex serum IFE5. These FLC assays are automated and allow same day analysis and reporting of results. Immunoglobulin free light chains (FLCs) are byproducts of immunoglobulin synthesis from plasma cells & in normal subjects are released into the circulation in small quanitities6. In patients with multiple myeloma, the clonal proliferation of plasma cells can produce FLCs in quantities thousands of times higher than normal7. The use of the kappa to lambda (k/ λ) ratio enables the identification of imbalances in light chain production. With these assays, the presence of monoclonal FLCs production is indicated when the ratio of kappa (k) to Lambda (λ) serum FLCs is outside the reference range of 0.26 – 1.658. We report here our experience with serum FLC assays in the diagnosis of MM in an Indian population in conjunction with SPE.

MATERIALS AND METHODS We have reviewed the cases of multiple myeloma which are diagnosed based on the International Myeloma Working Group (IMWG) diagnostic criteria for multiple myeloma (published in 2009)9. This study was undertaken during period 2009 & 2010, in the department of Lab Medicine, Basavatarakam IndoAmerican Cancer Hospital & Research Institute, Hyderabad, India. SPE was carried out using cellulose acetate strips (Genio Electrophoresis, Lilac). Serum Kappa & Lambda free light chain concentrations estimated by immunoturbidimetry on Olympus AU400 analyzer using reagents from the Binding site, UK. To confirm visual hypo or hyper immunoglobulinemia on SPE and as part of estimating concentrations of monoclonal immunoglobulin's, Immunoglobulin G, A, and M levels were estimated using turbidimetry on an Olympus AU400 analyzer. International Myeloma Working Group (IMWG) diagnostic Criteria for Symptomatic multiple myeloma9:

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Int J Pharm Bio Sci 2015 Jan; 6(1): (B) 1074 - 1080

All Three Required 1. Monoclonal plasma cells in the bone marrow >/=10% and/or presence of a Biopsy-proven plasmacytoma 2. Monoclonal protein present in the serum and/or urine) 3. Myeloma-related organ dysfunction (>/=1) [C] Calcium elevation in the blood (serum calcium >10.5 mg/dl or upper limit of normal) [R] Renal insufficiency (serum creatinine >2mg per 100 ml) [A] Anemia (hemoglobin