Band 39, Heft s1 - Translations

Clinical and experimental examinations showed a close relationship between zinc as an essential trace element and the immune system. Thus, cellular and humoral components from both the innate and the adaptive immune system are affected by zinc. Human zinc deficiencies are frequently connected with disturbed immune functions. Controlled zinc substitution results in a normalization of zinc serum levels, zinc homeostasis, and the immunological parameters. As shown in in vitro experiments, low zinc concentrations stimulate functional parameters of immune cells, but high zinc concentrations are suppressive or cytotoxic for these cells. Recently, the immunosuppressive effect of zinc was demonstrated in animal models of T-cell-dependent autoimmune diseases, like experimental autoimmune encephalomyelitis. Moreover, decreased serum/plasma zinc concentrations have been detected in patients with different autoimmune diseases. Prospective studies should verify the possibility of controlled immunosuppressive zinc therapies for these diseases.

Abstract: Lipoprotein(a) [Lp(a)] is one of the most atherogenic lipoproteins consisting of a core low-density lipoprotein particle and the specific glycoprotein apo(a). Apo(a) is homologous to plasminogen yet in contrast exhibits a specific size polymorphism. This polymorphism is due to the fact that the number of kringle-IV (K-IV) repeats ranges between two and approximately 50. Apo(a) is synthesized almost exclusively in the liver, and there is still some discussion regarding whether the assembly of Lp(a) occurs intracellularly or in the circulating blood. The plasma Lp(a) concentration is markedly skewed to the right and extends from <1 mg/dL to more than 200 mg/dL. Up to 90% of the variance of Lp(a) concentrations may be genetically determined and the Lp(a) concentration correlates inversely with the number of K-IV repeats. In the apo(a) promoter there are numerous response elements for transcription factors and nuclear receptors, whereby the HNF4α binding sequence is the most important one. Activation of FXR causes the dissociation of HNF4α from its response element and in turn a significant down regulation of apo(a) transcription. Recent large epidemiological studies document beyond any doubt that Lp(a) is an independent causal risk factor for coronary heart disease and myocardial infarction. Hence, novel approaches to correct elevated Lp(a) are under investigation. Among the established lipid-lowering drugs, only nicotinic acid lowers Lp(a) in a consistent and clinically relevant fashion, and we recently elucidated the molecular mechanism underlying this effect. Novel medicines in clinical trials include CETP inhibitors, PCSK9 antibodies, the MTP inhibitor lomitapide and antisense oligonucleotides. APO(a) Rx ® , an antisense oligonucleotide, which is specifically directed against the mRNA for apo(a), has the strongest effect on Lp(a). It offers the opportunity to examine the impact of selective Lp(a) lowering on clinical events. Lp(a) emerged as an important screening parameter to assess the risk for atherosclerosis. Its quantitation in the clinical laboratory had not been standardized for a long period of time. New commercial methods, in particular enzyme immunoassays with monoclonal antibodies that recognize single epitopes in apo(a), or nephelometric and turbidimetric assays hold the potential to warrant comparable results in different laboratories.

The diagnosis of hepatitis E virus (HEV) infections has been recently substantially facilitated by the introduction of a whole range of new different virological assays. The increasing appearance of sporadic cases of acute hepatitis E in Germany directed the focus toward the zoonotic transmission route of the virus. The recognition of HEV genotypes differing in virulence and in pathogenic potential is not only relevant for epidemiology and the course of the disease, but also for the development and choice of diagnostic tools. A broad variety of enzymatic and protein-based assay formats detecting anti-HEV IgG or IgM antibodies directed against the different genotype variants of HEV is available (ELISA, LIA, Western blot); however, sensitivity and specificity of these assays differ notably. Today’s state-of-the art technology that permits fast and reliable assay-based confirmation of HEV infections is PCR. The newly developed commercially available PCR kits will detect all four human pathogenic HEV genotypes. Further subdivision and discrimination can be achieved by sequencing, although this approach is only reasonable in the setting of specific epidemiological demands. Detection of viral antigens, cell culture, and T-cell assays are of no practical importance in a routine diagnostic setting. New insight into the pathogenesis and its clinical relevance for defined groups of patients (immunosuppressed) as well as the implementation of specific antiviral and prophylactic therapies (vaccination) will further challenge the performance of existing assay formats and increase the technical demands for the diagnostic laboratory.

The diagnosis of hemoglobin variants that are not any of the better-known forms of thalassemia, sickle cell, HbC, HbD, or HbE anomalies is often challenging and requires detailed knowledge of the difference in symptoms and analysis. Experience in laboratory medicine plays an important role as the range of variants is extensive and lack of expertise can result in a wrong diagnosis. Hemoglobin variants with low oxygen affinity may present cyanosis and low oxygen saturation levels, whereas variants with increased oxygen affinity show polyglobulia and concomitant complications. Differential diagnosis of methemoglobin variants requires careful assessment, which can be problematic especially in pediatric medicine. Other variants, due to their instability, can cause more or less distinct hemolysis or thalassemia syndromes depicting serious disease patterns. Clear distinction is not always possible as several symptoms are often present. Many variants are autosomal dominant inherited.

In vitro allergy diagnostics is rapidly advancing. This is primarily due to the development of component-based diagnostic tools. The availability of allergen components now allows a more precise and patient-tailored diagnostics, which has implications for therapeutic strategies including decision about specific immunotherapy. Furthermore, differential diagnostics of food intolerances and food allergies is also advancing because of this novel test. Another area of advancement is cellular diagnostics, which is primarily based on basophile activation tests. These recent developments will be discussed in this article.

Abstract: Myelodysplastic syndromes (MDS) are clonal malignant diseases of the hematopoietic stem cell. They are diagnosed mainly in elderly cytopenic patients and are characterized by a heterogeneous course of the disease. The diagnosis is based on blood and marrow cytology, chromosomal examination, and histology of the marrow, taking into account the degree of dysplasia, peripheral and medullary blast count, and cytogenetic findings according to the proposals of the World Health Organization (WHO) classification. The assessment of cytologic findings is important because the different types of MDS differ in terms of prognosis and therapeutic considerations. Acute myeloid leukemias are discriminated from MDS according to the blast counts in the bone marrow or peripheral blood (≥20%). Diagnosis is based on morphology and cytogenetics, and histology is also important. In addition, immunophenotyping and molecular investigations are needed. Information derived from cytogenetics and molecular markers play an important role for prognostication. Minimal residual disease can be best investigated using immunophenotyping and measurement of molecular markers.

Our article “A systematic approach to billing laboratory services – the legal framework” [Rathenberg et al., J Lab Med 2014;38(4):179–205] reviewed all relevant aspects of billing laboratory services. Here we provide supplementary information due to further legal advancements based on the German health-care law, with emphasis on specialist outpatient care ( Ambulante spezialfachärztliche Versorgung [ASV]) and selective contracts and complexes of services. In addition, we focus on occupational medicine as well as billing in connection with hospital emergency departments.

Abstract: In 1985 interleukin 6 (IL-6) was first identified as a differentiation factor for B-cells (B-cell stimulatory factor 2) which caused B-cells to mature and produce antibodies. Numerous studies now demonstrate the pleiotropic character of IL-6, which has been shown to possess important functions in the immune system, the regulation of hematopoesis, inflammation and oncogenesis. In the central nervous system (CNS), IL-6 is involved in neurogenesis and the response of neurons and glia-cells to various injuries. CNS infections, cerebral ischaemia, CNS traumata or chronic inflammatory diseases with CNS manifestations such as neuro-lupus or neuro-sarcoidosis are associated with increased IL-6 levels in the cerebrospinal fluid (CSF). Thus, the use of IL-6 as a diagnostic and prognostic tool in these diseases is being investigated. In this review we aim to provide an overview of current studies and evaluate the diagnostic significance of CSF-IL-6.

Abstract: The automated analysis of changes of white blood cells and their differential has become a high-throughput laboratory investigation done by hematology analyzers. The subsequent step of manual review of a stained blood film by light microscopy by an experienced investigator is laborious and expensive and has insufficient reimbursement. However, this is the decisive step and basis for very expensive specialized diagnostics like cytogenetics and molecular genetics. The strategy for a stepwise diagnostic procedure plays an important role at this stage. A new proposal is presented here.

Abstract: According to the recommendations of the IFCC and other organizations, medical laboratories should establish or at least adapt their own reference intervals, to make sure that they reflect the peculiar characteristics of the respective methods and patient collectives. In practice, however, this postulate is hard to fulfill. Therefore, two task forces of the DGKL (“AG Richtwerte” and “AG Bioinformatik”) have developed methods for the estimation of reference intervals from routine laboratory data. Here we describe a visual procedure, which can be performed on an Excel sheet without any programming knowledge. Patient values are plotted against the quantiles of the standard normal distribution (so-called QQ plot) using the NORM. INV function of Excel. If the examined population contains mainly non-diseased persons with approximately normally distributed values, the respective dots form a straight line. Very often the values are rather lognormally distributed; in this case the straight line can be detected after logarithmic transformation of the original values. Values, which do not match with the assumed theoretical distribution, deviate from the linear shape and can easily be identified and eliminated. Using the reduced data set, the mean value and standard deviation are calculated and the reference interval (μ±2σ) is estimated. The method yields plausible results with simulated and real data. With the increasing number of results, which do not match with the model, it tends to underestimate the standard deviation. In all cases, where the QQ plot does not yield a substantial linear part, the proposed method is not applicable.

Anemia is defined as a decrease in the hemoglobin concentration below the age- and sex-specific lower limit, established by WHO as 130 g/L in men and 120 g/L in women. In principle, there are many differential diagnoses which must be considered. The diagnostic evaluation furthermore is complicated by the fact that anemias are often multicausal. A rational evaluation of anemia should always take into account the epidemiological data and also the individual patient’s history. The classification according to the size and the hemoglobin content of the red blood cells based on the erythrocyte indices still plays a central diagnostic role. The worldwide most important cause of a hypochromic-microcytic anemia is iron deficiency. Anemia of chronic disease (ACD) and thalassemia are to be considered as differential diagnoses. Disorders of vitamin B12 and folic acid metabolism are clinically the most important causes of hyperchromic-macrocytic anemia. The normochromic-normocytic group includes most forms of anemias. In these cases one should not try to cover all possible causes by a fully comprehensive laboratory panel within the first blood sample already. It is more appropriate to proceed step-by-step to evaluate the most frequent and clinically most important reasons first. This especially applies to geriatric and multimorbid patients where the diagnostic effort must be adjusted to the individual needs and prognosis of the patient, not only from economical but also from ethical reasons. In unexplained anemias, consultation of a hematologist should be considered. In case of doubt, bone marrow biopsy is required to precisely evaluate the hematopoiesis and to exclude a hematological disorder.

Background: Reliable laboratory analysis is fundamental to diagnostics, therapy, and follow-up of growth disturbance and secretory dysfunction of growth hormone (GH) and insulin-like growth factor I (IGF-I). Currently available commercial assays have their limitations, as they show large variations in hormone concentrations measured. Methods: The recommendations of an expert workshop with practicing endocrinologists from the fields of pediatrics and internal medicine and with laboratory physicians, with reference to the outcome of the interdisciplinary consensus conference in Keswick (Virginia, USA) in 2009, were used. Results: Among the quality criteria stipulated by the workshop participants are the use of uniform reference standards, documentation of analytical conditions (such as calibrators, binding epitopes, cross-reactivity, and methods for removal from the binding protein), batch-to-batch consistency, and low inter-assay variability. The participants recommended developing assay-specific thresholds and reference intervals based on large and well-defined reference populations. It is furthermore recommended to delineate the assay quality, particularly with reference to clinically important cutoffs. Conclusions: The manufacturers of diagnostic assays should be obliged to regularly monitor and report the implementation of quality criteria. Only assays that are evaluated according to uniform quality standards and that are employed clinically permit informed diagnostic and therapy of patients with GH secretory dysfunction, preventing avoidable burden on both patients and paying authorities.

Hemoglobinopathies belong to the most common monogenic hereditary diseases worldwide. A particularly high prevalence is seen in the Mediterranean countries, in parts of Asia, the Middle East and West Africa. Nevertheless, due to migration hemoglobinopathies play an increasingly important role in Germany as well. Basic testing consists of blood count and hemoglobin differentiation. In addition, an iron deficiency should be excluded if necessary. Molecular genetic testing is used for the verification of hematologic findings and serves in the assessment of risk for a severe form of a hemoglobinopathy in offspring. In order to ensure efficient diagnostics, family history and previous findings of the patient should be communicated to the laboratory. This is especially crucial in the case of prenatal diagnostics.