Serum Protein Electrophoresis Results Research Articles

An up-conversion fluorescence lateral-flow immunoassay for rapid detection of Daratumumab in serum protein electrophoresis clinical samples

BackgroundDaratumumab (DARA) is a commonly used monoclonal antibody (mAb) drug for the treatment of multiple myeloma (MM). Its appearance as a visible abnormal band in the γ-region of a serum protein electrophoresis (SPEP) gel may interfere with the SPEP result interpretation. With the advantages of portability and rapid testing capabilities, up-conversion fluorescence lateral-flow immunoassay (LFA) can be an ideal solution to detect DARA interference. MethodsAn up-conversion fluorescence LFA strip was designed and constructed to perform semi-quantitative DARA testing in clinical samples. The LFA strip test was evaluated for limit of detection (LOD), dynamic range, and analytical interference. ResultsTo demonstrate the clinical utility of the LFA strip, 43 SPEP-positive patient serum samples were tested for the presence of DARA, and the results exactly matched the DARA usage history in patient medical records. ConclusionsThe performance of the up-conversion fluorescence LFA strip meets the purpose of clarifying DARA interference in SPEP results. It may be used as an independent and objective confirmation of the presence of DARA in clinical samples. The LFA strip offers a cost-effective rapid on-site test to check for DARA interference alongside standard SPEP equipment, which significantly improves the interpretation of ambiguous SPEP results involving DARA, and does not intervene the current SPEP workflow in clinical laboratory practice.

Update on the outcome of M-protein screening program of multiple myeloma in China: A 7-year cohort study.

To improve the early detection rate of multiple myeloma (MM), the M-protein screening system has been performed in the hospital population at Zhongshan Hospital Fudan University since 2014, with electrophoretic-based monoclonal immunoglobulin (M-protein) screening integrated into the blood biochemistry panel. This study updated 7-year follow-up findings of MM patients diagnosed by screening-driven and symptom-driven approaches. The retrospective study compared the characteristics and outcomes of patients diagnosed through two patterns by reviewing the plasma cell disease database from January 2014 to October 2021. The screening-driven group included patients diagnosed through the screening system during workups of unrelated medical conditions or routine checkups. In contrast, patients who visited or were referred to the hematological department due to myeloma-related end-organ damage were categorized into the symptom-driven group. There were 3,110,218 serum protein electrophoresis (SPEP) tests performed during 7 years, with 1.95% (60,609) patients yielding positive SPEP results. Of 911 confirmed MM cases (excluding concurrent amyloidosis), 366 were assigned to the screening-driven group, while 545 were to the symptom-driven group. Compared to the symptom-driven group, the screening group had more IgG subtypes, earlier International Stage System stages, fewer disease-related symptoms, lower ECOG scores, less extramedullary disease, a lower percentage of bone marrow plasma cells, and a lower level of lactate dehydrogenase. Frontline response results of two groups were similar. Patients detected through screening had a significantly improved median progression-free survival (PFS) than the symptom-driven group (62.2 vs. 24.9 months, p < 0.001, HR: 2.12, 95% CIs: 1.69-2.65), with median follow-ups of 32.6 and 27.4 months. Furthermore, the median overall survival (OS) was significantly longer in patients of the screening group (not reached vs. 62.3 months, p < 0.001, HR: 2.49, 95% CIs: 1.81-3.41). After being adjusted for well-acknowledged myeloma prognostic factors, the screening-driven diagnostic pattern remained an independent prognostic factor indicating improved PFS and OS in MM patients. Routine M-protein screening for MM in the hospital population results in an earlier diagnosis and better patient outcomes.

Serum-free light chain test utilisation at a South African academic laboratory and comparison with serum protein electrophoresis results.

Serum protein electrophoresis (SPE), urine protein electrophoresis and immunofixation electrophoresis were traditionally utilised for the diagnosis of monoclonal gammopathies. The quantitative serum-free light chain (SFLC) assay is reportedly more sensitive and has been introduced to recent clinical guidelines. This study aimed to investigate SFLC test utilisation and describe SPE findings in patients with abnormal SFLC ratios. A retrospective audit of SFLC analyses was conducted in Cape Town, South Africa, from May 2018 to April 2020. Agreement between abnormal SFLC ratios and SPE results was determined in a sub-group of patients screened for monoclonal gammopathies. Serum-free light chains were analysed using Freelite® Kappa and Lambda assays. Of the 1425 patients included in the audit, 741 (52%) had abnormal SFLC ratios; 636 (45%) had increased and 105 (7%) had decreased SFLC ratios. In a sub-group analysis of 117 new patients with an abnormal SFLC ratio, 57 had a monoclonal protein (M-protein) on SPE (49%), and 60 (51%) did not. Four out of 60 patients without M-protein had a plasma cell dyscrasia, while renal impairment or inflammatory response accounted for the rest. Of the 57 patients with a M-protein and abnormal SFLC ratio, 41 (72%) had a plasma cell dyscrasia, seven (12%) had lymphomas and nine patients (16%) were unclassifiable. Serum-free light chains should be requested when there is a high index of clinical suspicion. Neither SFLC nor SPE should be performed in isolation when screening patients for monoclonal gammopathy, to ensure that no patient is missed. The study adds to the evidence on SFLC test utilisation. Serum protein electrophoresis alone may miss cases of light chain myeloma, while SFLC performed in isolation may produce false positive results in the setting of inflammatory disorders or renal impairment, leading to unnecessary further investigation.

Effects of lipemia on capillary serum protein electrophoresis in native ultra-lipemic material and intravenous lipid emulsion added sera.

This study aims to investigate the effect of natural ultralipemic material (NULM) and intravenous lipid emulsion (IVLE) on capillary serum protein electrophoresis (SPEP). NULM material was prepared from leftover patients' lipemic serum sample (triglyceride concentration >2,000mg/dL) pool by a refrigerated high-speed centrifuge, and IVLE Omegaven lipid emulsion (30%) was used. Serum pools for interference study were prepared from patient samples for which serum protein electrophoresis was studied as Normal SPEP and M Peak SPEP. For both types of lipemia (DULM and IVLE), five pools with triglyceride concentrations of ∼4.52 mmol/L, ∼7.91 mmol/L, ∼14.69 mmol/L, ∼21.47 mmol/L, and ∼28.25mmol/L were prepared. SPEP was studied in each pool with Sebia Capillarys Minicap. A repeated measure ANOVA test was used to determine the difference between the pools, and interferograms were used to evaluate the interference effect. Interference was not detected in IVLE added Normal SPEP and M Peak SPEP pools, either % or concentrations of fractions. In NULM-added Normal SPEP and M Peak SPEP pools, significant positive interference in albumin % (p=0.002 and p<0.001 respectively) and significant negative interference in gamma% (p<0.001 and p=0.005 respectively) and M protein peak (p=0.002) fractions were detected. However, significant positive interference was seen only for albumin concentration fractions (p<0.001 for both pools). It is vital to use NULM instead of IVLE solutions in lipemia interference studies for all laboratory tests, including CZE SPEP. The fractions concentration values calculated with the total protein concentration should be used for evaluating SPEP results.

295 SPEP IT UP! DEVELOPING AN ALGORITHM FOR ABNORMAL SERUM PLASMA ELECTROPHORESIS RESULTS IN HIP FRACTURE PATIENTS

Abstract Background Hip fracture is a common manifestation of osteoporosis. All patients who sustain a hip fracture should receive a specialist bone health assessment, including Serum Protein Electrophoresis (SPEP) because plasma cell disorders such as multiple myeloma are an important differential diagnosis. SPEP results can be challenging to interpret without training and expertise. We aimed to review the proportion of abnormal SPEP results in hip fracture patients and used a newly developed algorithm to assess urgency of referral to haematology. Methods The Orthogeriatrics and Haematology teams collaborated to develop an algorithm to help facilitate decision making in hip fracture patients with abnormal SPEP results. A retrospective study was then conducted using data from the local Hip Fracture Database from Quarters 1 and 3 in 2020, and the hospital electronic laboratory system. The algorithm was used to retrospectively determine which patients warranted haematology review. The electronic appointment system was then accessed to review whether those who warranted haematology referral had appointments on the system. Results Of 270 hip fracture presentations, 19 duplicate records were excluded. Five patients had no data and three patients had passed away. Of the remaining 243 patients, 193 (79.42%) had SPEP’s sent. Abnormalities were detected in 116 patients (47.74%). According to the SPEP referral pathway, two patients warranted routine referral and one patient required an urgent referral, none of whom appeared to have been referred to haematology. Two patients who did not warrant haematology referral were already under haematology for different conditions. Conclusion Not all patients who sustain acute osteoporotic fractures with an abnormal SPEP result require haematology referral. The need for an urgent or routine haematology can be guided by the SPEP result along with other clinical features. With the introduction of this pathway, it is proposed that all hip fracture patients will be triaged in a timely, appropriate, and consistent manner.

Surveillance of Monoclonal Gammopathy of Undetermined Significance: A Proposed Change

Background:Monoclonal gammopathy of undetermined significance (MGUS) is a diagnosis that is often incidentally made after a serum protein electrophoresis (SPEP) is ordered as part of the evaluation for multiple nonspecific symptoms and is often ordered by non-hematologists. Currently, there is a lack of guidance regarding the extent of evaluation and follow-up required for these patients.Objective:Determine whether the risk stratification of the abnormal SPEP predicted progression to multiple myeloma (MM) or other lymphoplasmacytic malignancies (LPM) and could act as a guideline for appropriate follow-up in attempts to provide evidence-based, higher value care.Design:A retrospective review was performed of patients referred to the county hematology clinic for an abnormal SPEP from 2012 to 2019. The SPEP results were then risk-stratified and individual patient charts were reviewed to determine the symptomatology present at the time it was ordered, as well as the clinical course of the patients over time.Main Measures:Patients were stratified into low, low-intermediate, high-intermediate, and high risk groups for progression to MM based on the Mayo Clinic criteria. Additional information was also analyzed including the number of SPEP tests per patient, the indication stated for ordering the SPEP, and the presence of symptoms that are associated with MM at the time the SPEP was ordered, including anemia, renal failure, hypercalcemia, and bone lesions (commonly known as “CRAB symptoms”).Results:We abstracted data from 436 patients referred to the hematology clinic associated with a large county hospital system for an abnormal SPEP. The most common documented reasons for SPEP testing were increased creatinine (35%), protein gap (12%), and decreased hemoglobin (11%). Of these patients, 24 (5.5%) developed MM, 19 of whom were stratified into the high-intermediate risk group. More than a thousand SPEP results were obtained in the low and low-intermediate risk groups with only 5 patients diagnosed with MM. In the high-intermediate and low-intermediate risk groups, between 2-3 SPEP tests were performed prior to making the diagnosis of MM. In the low risk group, 6 SPEP tests were performed prior to reaching the MM diagnosis. Among the 5 patients in the low and low-intermediate risk groups who developed MM, all 5 had one or more of the CRAB symptoms at the time of the initial SPEP.Conclusion:Of the patients with MGUS who progressed to MM, approximately 80% were in the high-intermediate risk group. Of the remaining patients who progressed to MM from the lower risk groups, all had one or more of the previously mentioned CRAB symptoms, a higher percentage compared to the low and low-intermediate risk groups overall. In the absence of symptomatic disease, there is insufficient evidence to support serial SPEP testing in the lower risk patients. The use of evidence-based risk stratification may minimize unnecessary testing and hematology referrals while resulting in significant cost-savings and higher value care. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

A thin-film interferometry-based label-free immunoassay for the detection of daratumumab interference in serum protein electrophoresis

BackgroundDaratumumab (DARA) is a fully human anti-CD38 IgG1-κ monoclonal antibody drug used in the treatment of multiple myeloma (MM). While serum protein electrophoresis (SPEP) is an important assay for diagnosis and monitoring of patients with MM, DARA can appear in the γ-region as a single band and interfere with the interpretation of SPEP results. An approach to detect the interference is measuring the quantity of DARA in serum samples and assessing its impact on SPEP results. Immunoassays based on label-free technologies, i.e. label-free immunoassays (LFIA’s), can achieve real-time immunometric measurement without attaching a reporter molecule (enzyme, fluorophore, etc.) to the immunocomplex. The recorded time course of the immunocomplex formation allows for quantitation on initial binding rate, which facilitates rapid measurement within a few minutes. Based on the thin-film interferometry (TFI) technology, a rapid LFIA was established for the quantitation of DARA in serum samples. MethodsThe TFI-based LFIA for DARA was validated for imprecision (CV), accuracy, limit of quantitation (LOQ), and analytical measurement range (AMR). Interference to the LFIA was evaluated using a group of protein samples, as well as hemolytic, lipemic, and icteric clinical samples. ResultsThe precision of the TFI-based LFIA’s for DARA ranged from 6.5% to 10.7% (within-run CV), and 7.4% to 11.6% (between-run CV), with a bias of −2.1% to 10.1%. The LOQ was 10 μg/ml (n = 4, CV 9.8%), with an AMR ranging from the LOQ to 1000 μg/ml. The LFIA was used to measure 37 patient samples submitted for SPEP testing. The LFIA results were 100% consistent with the history of DARA use as documented in the medical record. ConclusionsThe TFI-based LFIA was successful at accurately identifying DARA in serum samples and can be used to identify DARA interference in SPEP testing. This work demonstrates the applicability of label-free technologies, particularly the TFI technology, to clinical diagnostic needs. Given the simplicity and the speed of the testing process, the TFI technology provides a unique testing approach for the measurement of proteins in clinical samples.

Clinical usefulness of serum free light chains measurement in patients with multiple myeloma: comparative analysis of two different tests

&lt;b&gt;Introduction:&lt;/b&gt; There are two commercially available tests for measurement of serum free light chains (sFLC) in multiple myeloma (MM) patients – Freelite and N Latex FLC. The aim of this study was to perform an assessment and direct comparison of the usefulness of the methods in routine clinical practice.&lt;br/&gt;&lt;b&gt;Methods:&lt;/b&gt; 40 refractory/relapsed MM patients underwent routine disease activity assessment studies, along with sFLC analysis using both assays. Correlation and concordance between the tests and sensitivity of studied methods of sFLC assessment were established. Special attention was focused on sFLC results in patients finally evaluated after completing the treatment. &lt;br/&gt;&lt;b&gt;Results:&lt;/b&gt; A weak correlation for the measurement of both κ [Passing–Bablok slope (PB) = 0.7681] and λ chains [(PB) = 1.542] was found. Using Bland–Altman plots, a bias of 0.0467 (κ) and -0.2133 (λ) between the measurements was documented. The concordance coefficient equaled 0.87 for κ, 0.62 for λ and 0.52 for κ/λ ratio. Ten patients had an abnormal Freelite assay κ/λ ratio and normal N Latex FLC κ/λ ratio. Three of these patients had negative serum protein electrophoresis results and fulfilled diagnostic criteria of stringent complete remission (sCR) according to N Latex FLC (but not according to Freelite). When the κ/λ ratio obtained by both methods was compared to patients’ serum/urine protein electrophoresis and immunofixation results, sensitivity of Freelite and N Latex FLC was established to be 62.5% and 41%, respectively. &lt;br/&gt;&lt;b&gt;Conclusions:&lt;/b&gt; There was no strong correlation or concordance between the two assays, and the sensitivity in terms of sFLC detection was different. This may cause problems when diagnosis of sCR is considered.

Multiclonality In Multiple Myeloma: A Retrospective Analysis Of Clonal Progression and Selection

IntroductionGenomic instability and multiclonality is the hallmark of many cancers including multiple myeloma (MM). Genetic alterations and clonal prominence occur over time as patients undergo various treatment modalities and can be followed by examining factors such as copy number abnormalities. Occasionally more than one monoclonal spike is noted on the serum protein electrophoresis (SPEP) indicating the existence of several distinct populations of clonal plasma cells producing a measurable amount of monoclonal (M) protein. Using routinely measureable clinical assays, SPEP and serum free light chains (SFL), we set out to identify the prevalence of multiclonality in patients with plasma cell dyscrasia, and to examine the natural history and effect treatment practices have on clones over time. MethodsWe retrospectively identified adult patients who were registered with the London Regional Cancer Program (LRCP), a tertiary care referral center in London, Ontario, Canada, since 2000 with a diagnosis of monoclonal gammopathy of uncertain significance (MGUS), smoldering myeloma, multiple myeloma or solitary plasmacytoma. Our current SPEP quantitation method has been in use since September 2004, so these SPEP results of patients identified from our initial search were examined for evidence of multiple monoclonal peaks as a surrogate marker for multiclonality. Inclusion criteria required a new diagnosis of plasma cell dyscrasia since the year 2000 and biclonal/multiclonal M protein peaks on SPEP followed through the LRCP. Demographics, SPEP results, treatment modalities and last recorded follow up or death for these patients was recorded. Outcome measures included quantification of complete remission, partial remission, very good partial remission and no response following systemic therapy to look for concordance in clone response. ResultsSince 2000, 1402 patients met the inclusion criteria; 144 patients met our surrogate criteria for multiclonality, representing a prevalence of approximately 10%. The majority of patients had MGUS (58, 40.3%) or MM (70, 48.6%) at first identification. Of these patients, 96 (66.7%) were male and the average age at diagnosis was 65.9 years. 58 (40.3%), primarily with MGUS, had no treatment and thus cannot be examined for treatment selective pressures. The number of clones identified ranged from two (114, 79.2%) to five. 62 (43.1%) had clones that were of similar immunoglobulin and light chain subtype, and half of patients had multiple clones identified at the same time point compared with development of clones during follow up investigations.In order to examine for concordance in treatment response between clones, we required that clones have a pre- and post- treatment value and have received systemic therapy with a measurable nadir. Only 26 patients had values that met these criteria, mainly due to clones disappearing with time, including 7 patients with no treatment, or oral treatment without recurrence and thus not quantifiable for comparison. Of these 26, approximately half showed discordance between clones, even in those with clones of the same M protein subtype. Of note, 4 discordant patients initially showed the same response to treatment and later developed divergent responses. DiscussionMulticlonality in plasma cell neoplasms is a common occurrence, with a prevalence of 10% in our patient population. The use of SPEP and SFL as surrogate markers for multiclonality likely underestimates the true prevalence of multiple clones measured by genetic methods due to insensitivity to resolved non secretory clones or multiple clones secreting similar immunoglobulin. As seen in previous studies, our results demonstrate that plasma cell clone response can diverge over time, potentially spontaneously or as a result of selection pressures imposed by therapy. These findings may help direct therapy and suggests prognosis as clonal divergence could herald genetic changes associated with therapy resistant disease. Disclosures:No relevant conflicts of interest to declare.

Polyclonal gammopathy related to renal bleeding in a peritoneal dialysis patient

Polyclonal gammopathy represents the diffuse activation of B cells and is usually related to inflammation or immune-related diseases. However, the mechanisms leading to polyclonal gammopathy are essentially speculative. Generally, infectious, inflammatory, or various other reactive processes may be indicated by the presence of a broad-based peak or band in the gamma region on serum protein electrophoresis results. A 15-year-old girl, who had been receiving peritoneal dialysis, presented with polyclonal gammopathy and massive gross hematuria. Renal artery embolization was performed, after which the continuous bleeding subsided and albumin-globulin dissociation resolved. This is a rare case of polyclonal gammopathy related to renal bleeding.

Evaluation of digital images for identification and characterization of monoclonal immunoglobulins by immunofixation

ObjectivesHigh resolution digital imaging systems were recently introduced to capture and visualize serum protein electrophoresis results. In this study, we compared the performance of five, experienced interpreters using digital images and physical gels to identify and characterize monoclonal gammopathies by immunofixation. Design and methodsImmunofixation gels were generated using Sebia's HYDRASYS and digital images were captured with Sebia's Gelscan system. Interpreters blindly reviewed 200 consecutively obtained immunofixation results using physical gels, low resolution (LR) images, and high resolution (HR) images. ResultsInterpretations of the physical gels were significantly more sensitive (p≤0.01) than LR and HR images, and significantly more specific (p<0.001) than the LR images. Interpreters had a sensitivity of 82.0% (45.8–95.7) using the LR images and a specificity of 71.0% (47.8–91.3); using the HR images interpreters had a sensitivity of 80.4% (68.1–86.8) and specificity of 91.8% (80.3–97.8). There was 73.6% agreement between the HR digital images and the physical gel for immunoglobulin isotype characterization. Interpreters using digital images collectively missed 19 patients with monoclonal immunoglobulins that were identified using physical gels. ConclusionsInterpreters using digital images had significantly different performance than when using physical agarose gels. Differences were most pronounced for low concentration monoclonal gammopathies (<0.3g/dL) and for complex patterns. Between-interpreter agreement was also lower using digital images. While digital images may serve as a useful resource for retrospective analysis and review of previous results, they are not equivalent to physical gels. Additional studies are warranted to explore the clinical impact of these observed differences.

Abstract 5557: Quantitative mass spectrometry assays for antibodies to measure multiple myeloma tumor burden and detect relapse

Abstract a) The goal of this study is to develop and characterize mass spectrometry assays for antibody quantification to assess multiple myeloma patients; the results generated from these peptide-based techniques will be compared data generated with gel-based and capillary serum protein electrophoresis (SPEP), which represents the current standard of care. b) Monoclonal antibody concentrations are currently determined using protein electrophoresis with either serum aliquots (SPEP) or Urine samples (UPEP), the specific class of myeloma is then determined using immunofixation. Liquid chromatography coupled to multiple reaction monitoring mass spectrometry (LC-MRM) assays have been developed to quantify all antibodies (Ig G, A, M, D, E, kappa, and lambda) and their isoforms in serum samples by measuring against known concentrations of stable isotope labeled internal standards using a triple quadrupole mass spectrometer. For assay development, at least two peptides representing each antibody isoform were derived from either LC-MS/MS runs based on excised gamma bands from stored SPEP gels of previous myeloma patients; these experimental results could also be supplemented by in silico workup of the protein sequence (i.e. theoretical peptide predictions). For each peptide target, several transitions (pairs of intact peptide masses and fragment ion masses) are programmed into the triple quadrupole for targeted detection using LC-MRM. Samples are analyzed in triplicate and compared with SPEP results. c) LC-MRM analysis has been performed on more than 40 serum samples collected from multiple myeloma patients. Using the selected peptides, protein amounts were calculated and compared with previous clinical SPEP results. The panel of antibodies presents unique opportunities and challenges for examining the utility of LC-MRM monitoring; for example, IgD and IgE increases can be detected with LC-MRM well below the 1 mg/ml limit of SPEP (at approximately 20 micrograms/ml). On the other hand, quantification of IgG1 with LC-MRM must be extremely accurate (&amp;lt; 10% CV) to detect the monoclonal protein against the background of that protein normally found in serum. To date, LC-MRM can detect all SPEP positive patients, and this method shows promise in detecting increases in antibody concentrations before they can be detected with SPEP. d) Quantitative mass spectrometry measurements for the antibodies combine the value of current SPEP and immunofixation experiments. Our results show that peptide-based monitoring can be as effective as protein-based monitoring. In addition, LC-MRM can detect light chain only disease, IgA myeloma that do not present a clear band in the gamma region of SPEP, and oligoclonal or polyclonal disease. These data enable broader commentary on the utility of LC-MRM in clinical protein measurements. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5557.

Detection by Immunofixation of M Proteins in Hypogammaglobulinemic Patients With Normal Serum Protein Electrophoresis Results

Serum protein electrophoresis (SPE) demonstrates a monoclonal protein as an M spike in the majority of patients with monoclonal gammopathies. However, in patients with an apparently normal SPE pattern or hypogammaglobulinemia, immunofixation electrophoresis (IFE) can reveal an M protein. We undertook this study to determine the yield of reflex IFE testing in patients with hypogammaglobulinemia and to identify any laboratory or biochemical parameters that would predict a positive IFE result. We evaluated 380 patients with hypogammaglobulinemia and a normal SPE pattern. Of 380, 37 (9.7%) had a positive IFE result in serum, urine, or both. Of the other laboratory values evaluated, a high alpha2-globulin level with an increased alpha2-globulin/alpha1-globulin ratio, a low hemoglobin level, and an elevated creatinine level predicted a positive IFE result. There was a 2-fold increase in the odds ratio for a positive IFE result when the alpha2-globulin/alpha1-globulin ratio was elevated. We recommend reflex IFE testing in patients with hypogammaglobulinemia with a normal SPE pattern if any of the following are present: elevated alpha2- globulin/alpha1-globulin ratio, low hemoglobin level, and elevated creatinine level.

Assessment of Serum Free Light Chain Assay for Screening for Plasma Cell Disorders.

Introduction and Methods: The purpose of this study was to evaluate the serum free light chain (FLC) assay in its ability to improve performance of protocols designed to screen for plasma cell disorders. We measured M-protein levels using serum protein electrophoresis (SPEP) in 312 consecutive patients being screened for plasma cell disorders at the Veterans Administration Medical Center - Puget Sound. The serum kappa and lambda free light chain levels were quantitated using the serum FLC assay in these same patients. The kappa/lambda ratio was calculated using the free kappa and free lambda results from the serum FLC assay.Results: SPEP results indicated the presence of a possible monoclonal gammopathy in 77 of the 312 patients in this study. In this group of 77 patients, a plasma cell disorder was diagnosed in 27 of them. The serum FLC assay showed an abnormal kappa/lambda ratio in 20 of these 77 patients, all 20 of whom were diagnosed with multiple myeloma. In the group of 235 patients with normal SPEP results, 17 were found to have an abnormal kappa/lambda ratio. Of these 17 patients, 15 were diagnosed with multiple myeloma, one with lymphoma, and one with bladder cancer.Conclusions: Because a number of disorders and diseases can increase production of immunoglobulins, there were a significant number of false positives in the SPEP results. At the same time, there were also several false negative SPEP results. The number of both false positives and false negatives was smaller for the serum FLC assay. Further, use of SPEP and the serum FLC assay together resulted in significantly improved sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). (See Table 1.) These results indicate an important role for the serum FLC assay in screening for monoclonal gammopathies.Table 1Performance of SPEP, sFLC, and both assays in screening for plasma cell disordersSPEP AlonesFLC AloneBoth SPEP and sFLCSensitivity64%88%100%Specificity81%98%99%Positive Predictive Value35%88%89%Negative Predictive Value94%98%100%

2-Mercaptoethanol Treatment Improves Measurement of an IgMκ M-Protein by Capillary Electrophoresis

A recent consensus conference on monoclonal gammopathies recommended the use of high-resolution electrophoresis, which achieves crisp separation of the major β-1 (transferrin) and β-2 (C3) bands (1)(2). Capillary electrophoresis (CE) provides this degree of resolution and has an additional advantage of automating both the analysis and the presentation of serum protein electrophoresis results (3)(4)(5). We report a rare discrepancy in the CE measurement of an IgM M-protein in the serum. The patient, a 59-year-old man, was first referred in August 1999 for evaluation of alcohol dependence, thrombocytopenia, and splenomegaly. Hemoglobin was 140 g/L, the white blood cell count was 4.7 × 109/L, and the platelet count was 54 × 109/L. A bone marrow aspirate was almost entirely plasmacytoid lymphocytes consistent with Waldenstrom macroglobulinemia. In addition to the lymphoproliferative process, the patient suffered from alcoholic hepatitis. On the day the sample …

Acute blindness associated with monoclonal gammopathy induced by Ehrlichia canis infection

Ehrlichia canis infection was diagnosed in a Labrador retriever presented with a primary complaint of acute blindness. Ocular signs on admission included bilateral hyphema, retinal haemorrhage and retinal detachment. Serum protein electrophoresis results revealed monoclonal gammopathy. This report discusses and suggests the pathogenesis of ocular bleeding in canine monocytic ehrlichiosis. Blood hyperviscosity, elevation in oncotic pressure, vasculitis, thrombocytopenia and platelet dysfunction are all proposed to be important factors in the pathogenesis of acute blindness in canine monocytic ehrlichiosis.