Giorgio Da Rin MD
Director
Laboratory Medicine
San Bassiano Hospital
Bassano del Grappa
Italy
The measurement of the length of sedimentation reaction in blood (LSRB) – commonly but improperly called erythrocyte sedimentation rate (ESR) – is a simple, routine laboratory technique. LSRB, the most widely used laboratory measure of disease activity in clinical medicine, is still considered useful for monitoring inflammatory diseases, particularly rheumatoid arthritis.
Recent reviews indicate that this test is widely used both for the diagnosis and the follow-up of patients with these conditions.(1-4) In fact, the value of LSRB in many rheumatologic diseases is well established. In particular, it is one of the criteria used for the diagnosis of polymyalgia rheumatica and giant cell arteritis, and for the monitoring of these and other rheumatologic diseases. A normal LSRB reduces the negative likelihood ratio of temporal arteritis to 0.2, and only 4% of patients with the disease present LSRB of 30mm or less. In polyarthralgia, the value of LSRB correlates well with the number of pain affected joints and it is a valuable marker of disease activity. In early rheumatoid arthritis, LSRB predicts the progression of joint damage.
While LSRB maintains its important role in the diagnosis and follow-up of rheumatoid arthritis, temporal arteritis and polymyalgia, it was recently reported to be of clinical significance in sickle cell disease, osteomyelitis and, surprisingly, in conditions such as stroke and coronary artery disease.(5-12) In acute coronary syndrome, LSRB testing has been described as being of prognostic value and an independent predictor of mortality – possibly confirming that the inflammatory cascade is causally involved in plaque rupture and thrombosis. In oncology, a high LSRB has been found to correlate with poor prognosis for various types of cancer, including Hodgkin’s disease. European studies of patients with Hodgkin’s disease suggest that an elevated LSRB may still be an excellent predictor of early relapse.(13)
San Bassiano Hospital
The laboratory at San Bassiano Hospital, Bassano del Grappa, Italy, provides a wide range of routine and specialised testing and clinical consultation to support diagnosis. It also monitors treatments of hospital inpatients and a large number of outpatients. The laboratory performs approximately 2.4 million tests/year, 50,000 of which are LSRB, and employs 35 fulltime staff. Modern laboratories committed to providing state-of-the-art, cost- effective testing, regularly translate developing technology into routine practice – by adopting new tests and improving upon existing ones. With this in mind we reorganised the haematology section of the laboratory in 2005. In relation to LSRB we are aiming to:
- Guarantee safety of operators by using automated and closed systems.
- Automate the measurement process and optimise the workflow and the utilisation of staff.
- Create a unique workstation for measuring LSRB and performing other haematological tests (eg, erythrocyte, leukocyte and reticulocyte concentrations) in a single specimen.
- Make the results of the test more widely and quickly available to physicians.
- Use a reference specimen (the undiluted specimen collected in K2EDTA) that is more reliable than the traditional sodium citrate as suggested by the International Council for Standardization in Haematology and the Clinical and Laboratory Standards Institute.
A new automatic system
Until recently, LSRB testing was performed using VES-matic (Diesse), a closed analyser programmed for the simultaneous determination of LSRB in 60 blood samples, which used rectangular plastic vacuum tubes containing sodium citrate as anticoagulant. In line with the reorganisation, we adopted VES-cube (Diesse), a new, closed automatic system for determining LSRB in K2EDTA tubes. The sample loader houses 20 racks, the same ones used by automated haematology analyser in random access mode. The system automatically reveals the erythrocyte sedimentation level by using two optoelectronic elements (LED + analogical photosensor). Data are then elaborated, printed and sent to the host computer. The system operates at a rate of 120 samples for the first hour and then at 190 samples/hour. The first result is obtained after 20 minutes and the following ones every 18 seconds. The samples in which LSRB is performed are automatically placed in a collecting rack. Their positions are identifiable by the instruments with alphanumeric coordinates, facilitating future research. The system possesses software that manages quality control, which is based on analysis of a stable control material.
Positive results
The advantages of using the VES-cube analyser in a clinical laboratory are reported as being: safety for operators, full automation, reduced turnaround time and limited analytic imprecision. However, in our opinion one of the major benefits is the use of undiluted K2EDTA-anticoagulated samples.
It is well known that LSRB is affected by red blood cell (RBC) aggregation or “rouleau” formation. In the blood of normal patients, RBCs suspended in the blood do not aggregate because they repel each other on account of their negative electric charge. In some pathological conditions we encounter a rise of plasmatic proteins as fibrinogens, gamma-globulins and alpha-globulins. These proteins, which have a positive charge, neutralise the RBC’s negative charges and promote the formation of erythrocytes agglomerate, which have the appearance of a coin pile or “rouleau”, that cause an increase of the erythrocytes sedimentation. However, some RBC morphological alterations (eg, anisocytosis and spherocytosis) may prevent rouleau formation because their morphology inhibits erythrocyte aggregation.
The collection of specimens with K2EDTA enhances blood cell stability, preserving morphologic features and obviating unphysiologic effects on the cells, and therefore favours rouleau formation. LSRB analysis from the same sample as the haematology analyser leads to further improvement: a smaller sample volume is required (particularly useful in newborns, children and oncology patients), sample collection and handling costs are reduced, and the use of the same racks as haematology analysers, available in random access, contributes in optimising the workflow in clinical laboratories.
In the past, two separate samples had to be used: one for the haematology analyser and one for the LSRB analyser. Now, with a single sample, we have a reduction in: the handover of samples in the laboratory; biological waste (reduction approximately 350kg/year); the amount of blood that needs to be taken (estimated reduction is 50 litres/year); and phlebotomy time (approximately 10 seconds/patient). Time saved by operators on the one hand is an advantage in poorly staffed teams, but on the other it can be used to improve relational aspects with patients. Furthermore, the use of undiluted and anti-coagulated blood with K2EDTA reduces the risk of preanalytic mistakes caused by small blood clots or partially coagulated specimens, or by an altered blood/sodium citrate ratio. The use of standard test tubes instead of rectangular ones permits more precision when taking samples of blood.
The traceability of the K2EDTA tube selected by LSRB, together with the possibility of using a stable control to monitor precision and bias – although the LSRB procedure cannot be calibrated and it is inherently stable – is very important in relation to quality assurance, certification and accreditation given that clinical laboratories must document the quality of LSRB measurements.
Conclusion
This innovative analyser has many advantages (eg, reducing analytical time and improving productivity, analytical precision and accuracy). Analytical improvements, however, are not enough. While the main task of laboratory scientists used to be control and improving the analytical part of the total testing process with reliable results, today they also need to evaluate the appropriateness of test requests. The usefulness of the tests in clinical practice, clinical efficacy of laboratory results and their impact on clinical outcome must also be evaluated, therefore maximising the impact of laboratory information on patient management.
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