Unreliability in immunoassays of erythropoietin: anomalous estimates with an assay kit

Procedures for monitoring recombinant erythropoietin and analogues in doping control

The present report summarizes the main analytical strategies developed to identify the presence of recombinant erythropoietin (EPO) administered as a doping agent. Indirect evidence is based on the analysis of blood parameters (haemoglobin, haematocrit, reticulocytes, macrocytes, etc.) and serum markers (concentration of EPO and serum transferrin receptors, etc.). The problem of intertechnique comparison for reliable results evaluation is emphasized, especially for serum markers. Charge differences between isoforms of recombinant EPO and native urinary EPO are the grounds for the isoelectric focusing-double blotting-chemiluminescence detection method presently approved for doping control. Works addressing its advantages and limitations are presented and commented on. The chemical bases of the differential detection are highlighted and some future approaches for detection are also presented. The appearance and detectability of EPO analogues and mimetics susceptible for abuse are also addressed.

A sample distribution programme for erythropoietin

A survey was sent to laboratories participating in the United Kingdom External Quality Assessment Service (UKNEQAS) Haematinics Scheme about the measurement of serum erythropoietin (EPO). Six laboratories, from a total of 120 that returned the survey, were measuring serum EPO concentrations by commercially available immunoassays on site in the United Kingdom. The workload of the laboratories varied from up to 100 specimens per month to more than 100 specimens analysed per week. All laboratories included control material in the assays and none of the laboratories was participating in an external quality assessment scheme for serum EPO. Four laboratories agreed to take part in the first sample distribution programme, with five and six laboratories participating in distributions 2 and 3 respectively. The results from eight kits were compared from the three distributions over a 2-year period. The serum EPO concentrations for the methods showed some variation across the range of 2.9-200 U/l when the serum EPO concentrations for each method were compared with the whole method mean. The results from this scheme have identified a role for an external quality assessment scheme for serum EPO measurements.

Laboratory screening for erythropoietin abuse in sport: an emerging challenge

The growing diffusion of banned practice to improve the athletic performances is forcing clinical laboratories to identify and standardize reliable assays to detect potential unfairness. Among the doping practices, the use of recombinant human erythropoietin is becoming fairly popular, due to simplicity and safeties of administration and troublesome detection. The heterogeneous response rate, the presence of a little but significant amount of naturally occurring hormone, the short half-life exhibited by recombinant human erythropoietin and the lack of standardization of commercial assays appear the main problems to overcome. Aim of the present article is to provide a critical review of some of the more widespread laboratory techniques currently available for the screening for erythropoietin abuse in sport.

Effect of iron on erythropoietin production in anaemic piglets

In the present study the response of plasma erythropoietin to iron injection in anaemic piglets was examined. At the age of 16 days, 4 piglets from the same litter were given 180 mg iron subcutaneously. After iron injection, blood samples for estimation of erythropoietin activity in plasma, haemoglobin concentration, and reticulocyte counts were taken every 6 or 12 h for 3 1/2 days. Plasma erythropoietin activity was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human erythropoietin. On the day of iron injection, haemoglobin concentration ranged between 41 and 48 g/l, reticulocyte counts from 9 to 17 percent, and plasma erythropoietin between 22 and 144 mU/ml. In 3 of the 4 piglets, iron injection resulted in a 2-6 fold increase in erythropoietin activity. Maximal erythropoietin activities were observed 24-42 h after injection, and after 66 h, the activities were close to the pretreatment values. It is concluded that in our experiment, iron, per se, has stimulated erythropoietin production.

Serum immunoreactive erythropoietin in hyper- and hypothyroidism: clinical observations related to cell culture studies

Laboratory experiments have demonstrated that tetra- and triiodothyronine (T4, T3) enhance hypoxia-induced erythropoietin (Epo) production. In the present study serum immunoreactive Epo was measured in 29 patients with hyperthyroidism and in 10 patients with hypothyroidism. Epo levels were inversely correlated to the blood haemoglobin concentration [Hb] in both groups of patients. However, Epo levels at given [Hb] were significantly higher in the hyperthyroid state. In vitro studies confirmed that T4 and T3 stimulate Epo synthesis in the human liver cell line HepG2. This stimulating effect persisted for at least 1 day after the removal of T4 and T3 from the cultures. Thus, while thyroidal disorders affect steady-state levels of circulating Epo, it seems unlikely that thyroid hormones play a major role in abrupt adjustments of Epo production, such as the diurnal changes.

Inadequate erythropoietin response to anemia: definition and clinical relevance

The development of a specific and sensitive immunoassay for the measurement of serum erythropoietin (s-Epo) allows to improve our understanding of the model of in vivo regulation of erythropoiesis. In most anemias, circulating hemoglobin level determines Epo production which in turn stimulates erythropoietic activity. The disruption of the expected feedback mechanism of Epo production leads to an inadequately low s-Epo. The definition of inadequate Epo response to anemia relies on the documentation of a downregulated dependence of s-Epo on Hb with respect to the same dependence in patients with a physiologically regulated erythropoiesis. Literature reports a wide range of so called adequate s-Epo response to anemia and a number of criteria for judging on the adequateness of s-Epo at a certain degree of anemia. The O/P (observed/predicted) ratio allows categorization of each individual patient. The clinical syndromes in which an inadequate Epo response has been reported are numerous and the mechanisms of defective Epo production are different. A number of evidences clearly point to a relation between responsiveness to r-Hu-Epo and inadequate Epo response. This inequivocabily confirms the role inadequate Epo response plays in the pathogenesis of anemia.