A new approach for rapid detection and typing of serum monoclonal components.

When used independently, none of the routine methods to explore serum monoclonal components (MC), including: serum protein electrophoresis (SPE), immunoelectrophoresis (IEP), kappa to lambda ratio (KLR) and immunofixation (IFE), provides a comprehensive quantitative and qualitative identification of the MC. In the past few years the concept of 'protein profile', based on immunonephelometric quantifications of serum proteins, has become widely used. It consists of a qualitative and quantitative graphic representation of numerous serum proteins including immunoglobulins. Aim of study was to develop a multidimensional model based exclusively on protein profiles labeled the protein profile prediction method (PPPM) to improve routine MC detection and typing. Serum samples from 127 hospitalized patients and 99 healthy blood donors were submitted to all of the following: SPE, IFE, KLR and a protein profile (which included IgM, IgA, IgG, kappa and lambda chain detections and quantification). The presence of a MC using IFE was chosen as the gold standard. Healthy donors and patients were randomly divided into two groups defined as testing and validation groups. A logistic model was designed based on the protein profiles of the testing group leading to the determination of a threshold value (called Z(r)) for MC detection. It was then tested to detect MC in the validation group. Using IFE, 73 MC were found in the 127 hospitalized patients. Using the threshold value for MC detection of Z(r)=1.86, the PPPM showed greater sensitivity (94.6%) in detecting a MC compared to either SPE (64.8%) or KLR (89.2%). This result was obtained without diminished specificity (80.8%). The association of SPE or KLR to PPPM did not significantly increase the sensitivity of the PPPM. In the validation group, for samples which had a high predictive probability of a MC using PPPM, the correct MC typing was identified in up to 77% of sera using PPPM only. These results may be interesting in helping to determine when supplementary IFE analysis is required to qualitatively analyze a MC. PPPM allows MC detection with great sensitivity. The immune protein profile dramatically increases the sensitivity of either SPE and/or KLR in detecting MC and may also allow heavy and light chain typing.

[Protein profile and iron deficiency: value of the study of the albumin-transferrin couple]. / Profil protéique et carence martiale: intérêt de l'étude du couple albumine-transferrine.

From a clinical standpoint, the search for iron deficiency is based upon serum ferritin. However, serumferritin values may be pathologic in other numerous pathological conditions such as inflammation, liver diseases, malignant hematologic disorders, hemolysis, etc. Proteic profile combines the analyze of proteins variations: protein results are converted in percent of normal values referenced for the technique used. It has been suggested that on the protein profile, an increase in serum transferrin level compared to a normal serum albumin level (DAT: difference albumin-transferrin), appears early in the course of iron deficiency. In order to know the value of a pathologic DAT > or = 28% in the diagnosis of iron deficiency, we prospectively studied 156 patients consecutively hospitalized in an internal medicine department. Iron deficiency was defined by a low serum ferritin level. Diagnosis performance (sensitivity, specificity, positive and negative predictive values) of different biologic markers of iron deficiency (serum iron, saturation of total iron-binding capacity, low mean erythrocyte volume) and DAT was compared to the performance of low serum ferritin values. With the exception of low serum ferritin (which have by definition a specificity and a positive predictive value of 100%), pathologic DAT appeared as the best index of iron deficiency with the highest sensitivity (67.4%), specificity (97.3%), positive predictive value (91.2%), negative predicitive value (87.7%) and diagnosis efficacy (sensitivity x specificity = 0.66). A pathologic DAT associated to a low serum ferritin level increased the diagnosis performance of both tests to 0.72. Diagnosis efficacy of DAT was not changed (0.66) in 83 patients with a confounding factor for serum ferritin analysis (inflammation, liver diseases, malignant hematologic disorders, hemolysis) when diagnosis efficacy of all other tests decreased. There was a negative correlation between serum ferritin level and DAT level (r = 0.55; P < 0.0001). In conclusion, an increase of serum transferrin of more than 28% compared to serum albumin on a proteic profile gives a significant benefit for the diagnosis of iron deficiency. This benefit increases when data of both DAT and serum ferritin are associated.

[Importance of the protein profile in internal medicine]. / Intérêt du profil protéique en médecine interne.

Until recent years, main biologic markers of inflammation used in current practice were limited to erythrocyte sedimentation rate, fibrinogen, and serum protein electrophoresis. A better understanding of inflammatory mechanisms and improvement of laboratories technologies helped in better understanding of the role and potential usefulness of inflammatory reaction proteins. Arrival of proteic profile and, more recently, the development of automation, still improved analysis of variations of different inflammatory reaction proteins. These proteins are then analyzed as an element of a "functional biological system", with known and so expected kinetics and ranges. The analyze of proteic profile combines the analyze of proteins variations, with elected but not exclusive associations, as Immunoglobulins and Complement, Orosomucoid and Haptoglobin, or Albumin and Transferrin. In Internal Medicine, proteic profile may help in solving daily problems. These problems may be so schematized: when the fundamental pathology is not yet known in an unraveling check-up, facing clinical symptoms, with a normal or fewly disrupted usual biologic panel, proteic profile may help to choose investigations necessary for the diagnosis; in the follow-up of patients treated for known inflammatory pathology facing new symptoms, part has to be done between complication of the disease and/or of the treatment, new pathology associated or unefficiency of the treatment. We report herein part of our experience of proteic profile in an Internal Medicine department, from some particularly demonstrative case reports: congenital or acquired abnormality of iron metabolism, with normal usual iron panel (iron deficiency, hemochromatosis); severe evolutive inflammatory or infectious disease with normal erythrocyte sedimentation rate (temporal arteritis, infectious endocarditis).