Ionized calcium: whole blood, plasma or serum?

OBJECTIVES: To determine an optimal specimen type to be used for measurements of ionized calcium (iCa) so that it applies properly to the reference interval. Also to determine the validity of the pH correction that is applied to iCa measurements. METHODS: A reference interval study of normal volunteers was performed using four sample types namely balanced heparin (BH) whole blood, lithium heparin (LH) whole blood, plasma and serum. The sample was treated in an anaerobic fashion and analyzed at 0 and 40 minutes after venipuncture. The effect of pH correction as well as analysis time after collection was also studied. RESULTS: The mean iCa was the highest in BH-treated whole blood when measured immediately. However, it was slightly lower at 40 min after collection (p < 0.001). In contrast, there did not appear to be a significant difference in results when LH-treated whole blood was analyzed at 0 or 40 min. The reference interval for serum was similar to that of whole blood. The reference interval for plasma was dramatically lower than whole blood and plasma. The reference intervals for pH adjusted ionized calcium (iCa-adj) were dramatically lower than those from all specimens without adjustment. The reason for this was that the reference interval for pH in this study had a strong alkaline bias on one instrument and a strong acidic bias on the other. CONCLUSIONS: The sample of choice for ionized calcium analysis appears to be whole blood with either BH or LH. For the LH specimen, there is no significant change over 40 min whereas there is significant change for the BH specimens (-0.030 mmol/L, p < 0.0001). iCa-adj should not be used unless (i) very strict attention is paid to standardization of both the calcium and the pH and (ii) there is a very good reason to believe that the patients' pH is normal at 7.4.     

Controlling inflammation: a fat chance?

The inflammatory response protects the body against infection and injury but can itself become deregulated with deleterious consequences to the host. It is now clear that several endogenous biochemical pathways activated during defense reactions can counterregulate inflammation. New experimental evidence adds resolvin E1 to this group of endogenous inhibitors and provides further rationale for the beneficial effects of dietary supplementation with fish oils. It also highlights an unexpected twist in the pharmacology of aspirin.     

The efficient organization of blood donation: what determines the number of donors and donations?

This study investigates the influence of socio-economic characteristics on the number of donors in geographical areas in the North of Scotland as well as the influence of panel-specific characteristics on the number of donations obtained from each panel in the North of Scotland. Econometric models are applied to establish the relationship between these variables. The main findings were that there was no scope for identifying new areas in which to locate new panels or extend the activities of existing panels because the number of donors in an area was closely correlated with population. There was therefore little scope for recruitment of donors by focusing on any particular area. It was found that annual donations per panel are significantly influenced by the number of donors invited, the number of opportunities to donate and the average length of sessions. Combined with cost information, increasing the length of the session appears to be the most cost-effective means of collecting higher volumes.     

Biospecimen repositories: are blood donors willing to participate?

BACKGROUND: Sponsored by the National Heart, Lung, and Blood Institute, the Retrovirus Epidemiology Donor Studies (REDS‐I/‐II) have conducted epidemiologic, laboratory, and survey research on volunteer blood donors. Some studies request additional permission to store biospecimens for future studies. The representativeness and applicability of studies performed using repositories may be reduced by low participation rates. STUDY DESIGN AND METHODS: Demographics from subjects consenting to participate in the 2007 REDS‐II Leukocyte Antibodies Prevalence Study (LAPS) repository were compared to “study‐only” subjects. Data from the 1998 REDS‐I survey of donor opinion regarding storage and use of biospecimens were also explored. RESULTS: Overall, 91% of LAPS subjects agreed to participate in the repository. Odds of repository participation were lower among African American and Hispanic donors, 35‐ to 44‐year‐olds, donors who had not completed high school, and donors from one geographic location, regardless of other variables. Survey data from 1998 revealed that 97% of respondents approved of long‐term storage of biospecimens, although only 87% indicated that they would personally participate. Many respondents would require notification or their permission be obtained before participation. Minority respondents would require permission or notification more often and were less certain they would personally participate in a repository. CONCLUSION: Blood donors are quite willing to participate in biospecimen repositories. Regional differences and lower odds of participation in the minority blood donor population may result in a reduced number of biospecimens available for study and a decreased ability to definitely answer specific research questions in these populations.     

Treatment of tendinopathy: is there a role for autologous whole blood and platelet rich plasma injection?

Background: Chronic tendinopathies are a common source of disability and can be recalcitrant to conservative measures, which once exhausted may necessitate operative intervention. Blood and platelets, in particular, are a rich source of factors necessary for tissue healing. Autologous blood injections (ABI) are thought to promote tendon healing, but have been explored clinically in only a few limited studies. However, recently they have attracted media attention in relation to the world of professional athletes and sports‐related injuries. Method: We review the evidence base for this technique using the available literature on PubMed. Conclusion: Refractory chronic tendinopathy may be responsive to ABIs, but the data available to date are limited by quality and size of study, as well as length of follow up, and are currently insufficient to recommend this modality for routine clinical use.     

Can capillary whole blood glucose and venous plasma glucose measurements be used interchangeably in diagnosis of diabetes mellitus?

According to new proposals from the American Diabetes Association (ADA) and WHO, venous peripheral plasma is the preferred system for measuring glucose for diagnosing diabetes mellitus. Owing to the instability of glucose in plasma after blood sampling, strict well-defined and standardized preanalytical conditions are essential to ensure that glucose concentration measured in plasma reflects real blood glucose in the patient. This is in contrast to the capillary whole blood measurements, which are easy to perform and well established. We investigated whether it is possible to perform analysis on capillary whole blood but express the results as plasma glucose values and hence obtain comparable results and the same predictive values for diagnosis in the individual patient? The conclusion of our investigations is that these two systems are not interchangeable and that conversion should not be done for diagnostic purposes where plasma determinations are recommended.     

A randomized controlled trial oftransfusion‐related acute lung injury: is plasma from multiparous blood donors dangerous?

BACKGROUND: Transfusion-related acute lung injury (TRALI) and other posttransfusion reactions may be caused by granulocyte and/or HLA antibodies, which are often present in blood from multiparous donors. The purpose of this study was to compare the effects of plasma from multiparous donors with those of plasma from donors with no history of transfusion or pregnancy (control plasma) in a prospective, randomized, double-blind, crossover study. STUDY DESIGN AND METHODS: Intensive care patients, judged to need at least 2 units of plasma, were randomly assigned to receive a unit of control plasma and, 4 hours later, a plasma unit from a multiparous donor (> or = 3 live births) or to receive the plasma units in opposite order. The patients were closely monitored, and body temperature, blood pressure, and heart rate were recorded. Blood samples for analysis of blood gases, TNFalpha, IL-1 receptor antagonist, soluble E selectin, and C3d complement factor were collected at least on four occasions (before and after the transfusion of each unit). RESULTS: Transfusion of plasma from multiparous donors was associated with significantly lower oxygen saturation and higher TNFalpha concentrations than transfusion of control plasma. The mean arterial pressure increased significantly after the transfusion of control plasma, whereas plasma from multiparous donors had no effect on it. Five posttransfusion reactions were observed in 100 patients, in four cases after the transfusion of plasma from multiparous donors. CONCLUSION: Plasma from multiparous blood donors may impair pulmonary function in intensive care unit patients.