Proceedings of the 2022 NHLBI and OASH state of the science in transfusion medicine symposium

BACKGROUND

State of the Science (SoS) meetings are used to define and highlight important unanswered scientific questions. The National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, and the Office of the Assistant Secretary for Health (OASH), Department of Health and Human Services held a virtual SoS in transfusion medicine (TM) symposium.

STUDY DESIGN AND METHODS

In advance of the symposium, six multidisciplinary working groups (WG) convened to define research priorities in the areas of: blood donors and the supply, optimizing transfusion outcomes for recipients, emerging infections, mechanistic aspects of components and transfusion, new computational methods in transfusion science, and impact of health disparities on donors and recipients. The overall objective was to identify key basic, translational, and clinical research questions that will help to increase and diversify the volunteer donor pool, ensure safe and effective transfusion strategies for recipients, and identify which blood products from which donors best meet the clinical needs of specific recipient populations.

RESULTS

On August 29-30, 2022, over 400 researchers, clinicians, industry experts, government officials, community members, and patient advocates discussed the research priorities presented by each WG. Dialogue focused on the five highest priority research areas identified by each WG and included the rationale, proposed methodological approaches, feasibility, and barriers for success.

DISCUSSION

This report summarizes the key ideas and research priorities identified during the NHLBI/OASH SoS in TM symposium. The report highlights major gaps in our current knowledge and provides a road map for TM research.

Screening for familial hypercholesterolaemia; extending a role for blood programs in promoting public health

Background

Familial hypercholesterolaemia (FH) is a genetic disorder characterized by high levels of cholesterol with evidence of coronary arterial disease at an early age. The prevalence of FH has been recently reported as 1/200 to 1/250 in the general population and although early identification and treatment is recommended (2019 ESC/EAS Guidelines for the Management of Dyslipidaemias), the disorder is largely underdiagnosed in asymptomatic individuals.1

A number of blood programs has recognised the opportunity that blood donation provides to identify ostensibly healthy individuals who might be unaware of risks to their health. These programs have included, along with mandated serological testing, such assays as non-fasting total cholesterol (TC) and haemoglobin A1C. They have also taken steps to notify individuals whose results suggest risk for cardiovascular disease or diabetes.

Purpose

Since our blood donation program has a long history of providing donors information about their TC, we tested whether some donors with elevated TC met the criteria for FH.

Methods

We reviewed unlinked total non-fasting cholesterol results from volunteers donating between 2015 and June 2019. Cholesterols were measured on a chemistry analyzer system (Beckman Coulter AU680) on residual blood after routine testing for infectious disease markers. For volunteers donating more than once, we included only their highest TC recording. TC was classified by American Heart Association (AHA) 2020 Goal Metrics as high, if ≥240 mg/dL (6.2 mmol/L) in donors ≥20 years of age and ≥200 (5.1 mmol/L) in donors <20 years of age. 2 We applied the United States Center for Disease Control Cooperative MEDPED diagnostic criteria for FH. Using these criteria, FH is diagnosed when TC exceeds 270 mg/dL (7.0 mmol/L) in individuals less than 20, 290 mg/dL (7.5 mmol/L) in individuals 20 to 29, 340 mg/dL (8.8 mmol/L) in individuals 30 to 39, and 360 mg/dL (9.3 mmol/L) in individuals 40 years of age and older. 3

Results

There were 432,389 unique donors during the study period. The overall prevalence of high cholesterol, 11.1% and the prevalence of FH 0.24% are similar to published data for the general population. As shown in the table, the prevalence of FH was highest in blood donors 20 to 29 years of age and was lower in those over 30 years, while the prevalence of high TC was higher in older age groups.

Conclusion

There is a subset of blood donors, at all ages who can be identified as satisfying familial hypercholesterolaemia criteria that could benefit from additional evaluation and family screening. A sizeable proportion of blood donors have high cholesterol despite not having FH.

Funding Acknowledgement

Type of funding sources: None.

Identifying Familial Hypercholesterolemia Using a Blood Donor Screening Program With More Than 1 Million Volunteer Donors

Importance

Familial hypercholesterolemia is an autosomal-dominant disorder that often causes premature coronary artery disease. Unfortunately, familial hypercholesterolemia remains largely undiagnosed.

Objective

To estimate the prevalence of familial hypercholesterolemia in a population of blood donors.

Design

This analysis of deidentified data from blood donors 16 years and older who donated to Carter BloodCare, one of the largest independent blood programs in the United States, between January 2002 and December 2016. Carter BloodCare, which serves a population of about 8 million in Texas, routinely measures total nonfasting serum cholesterol levels as part of a donor health screening program. Data analysis occurred from October 2017 to March 2019.

Exposure

Blood donation.

Main Outcomes and Measures

Familial hypercholesterolemia was defined using the Make Early Diagnosis to Prevent Early Death general population criteria, with total nonfasting serum cholesterol thresholds of 270, 290, 340, and 360 mg/dL for donors younger than 20 years, 20 to 29 years, 30 to 39 years, and 40 years or older, respectively (to convert cholesterol values to mmol/L, multiply by 0.0259). For repeated donors, the maximum observed total cholesterol level was used for analyses.

Results

The study included 1 178 102 individual donors with a total of 3 038 420 blood donations. Of all individual donors (median total cholesterol level, 183 [interquartile range (IQR), 157-212] mg/dL; median age, 32 [IQR, 19-47] years; 619 583 [52.6%] women), a total of 3473 individuals (or 1 in every 339) met criteria for familial hypercholesterolemia. This group had a median (IQR) total cholesterol of 332 (297-377) mg/dL. Estimated prevalence was higher at younger ages (<30 years: 1:257) compared with older ages (≥30 years: 1:469; P < .001) and in men (1:327) compared with women (1:351; P = .03). Among 2219 repeated donors who met familial hypercholesterolemia criteria at least once, 3116 of 10 833 total donations (28.8%) met FH criteria.

Conclusions and Relevance

The prevalence of familial hypercholesterolemia using the Make Early Diagnosis to Prevent Early Death criteria in a large cohort of blood donors was similar to the estimated prevalence of this disorder in the general population. The blood donor screening program could be a novel strategy to detect and notify individuals with potential familial hypercholesterolemia, particularly younger individuals in whom early detection and treatment is especially helpful, as well as guide cascade screening.

Abstract P395: Blood Pressure Screening in Teenage Blood Donors Using the New American Academy of Pediatrics Guidelines

Background: Screening of youngsters is valuable in identifying current or future health risk. Since approximately 20% of all blood donated in the U.S. comes from teenagers, blood donation is an opportunity to screen younger individuals. We decided to capitalize on this opportunity and investigate the prevalence of abnormal blood pressure in teenagers using the new American Academy of Pediatrics (AAP) guidelines which lowered the threshold for what could be considered a raised blood pressure. Since comparative data are limited in this age group we also decided to report our results by gender and race.

Study: Participants were volunteer donors at high schools, aged 16-19 years, who donated between 2015 and 2017. Blood pressure was measured using automated equipment (Welch Allyn, ProBP). Blood pressure was classified as suggested by the AAP: normal (<120/<80), prehypertension (120/<80 to129/<80), Stage 1 hypertension (130/80 to139/89), and stage 2 hypertension (≥140/90). Donors were invited to declare their ethnicity at the time of donation.

Results: During the study period there were 80,950 individual donors,10.8% (8,774) were African American, 4.2% (3,410) Asian, 51.9% (42,040) Caucasian and 33.0% (26,726) Hispanic. More males than females, in all ethnicities, had blood pressures above normal. % 16 - 19 year old blood donors (donating from 2015-2017) categorized by the AAP blood pressure guidelines, by ethnicity and gender (N=80,950)

Conclusion: Blood donation is confirmed as an opportunity to screen blood pressure in an ostensibly healthy subset of the younger population. This scrutiny does identify teenagers deserving follow up and also reveals ethnic and gender differences.

Transfusion-transmitted babesiosis in Washington State: first reported case caused by a WA1-type parasite

Most cases of babesiosis reported in the United States have been tickborne and caused by Babesia microti, the etiologic agent of all previously described transfusion-transmitted cases. A 76-year-old man with the first recognized case of transfusion-transmitted infection with the recently identified WA1-type Babesia parasite is described. The subject received multiple blood transfusions in 1994. Indirect immunofluorescent antibody testing of serum from 57 blood donors implicated a 34-year-old man (WA1 titer, 1:65,536) whose donation had been used for packed red cells. Isolates of the organisms that infected the recipient and the donor, both of whom were spleen-intact residents of Washington State, were obtained by hamster inoculation. The DNA sequence of a 536-bp region of the nuclear small subunit-rRNA gene of both isolates was identical to that of WA1 (isolated in 1991 from the index WA1 case-patient). Effective measures for preventing transmission of babesiosis by blood transfusion are needed.

Hepatitis C virus (HCV) infection in bone marrow transplant patients after transfusions from anti-HCV-positive blood donors

In March 1992, 12 bone marrow transplant patients at the Fred Hutchinson Cancer Research Center received blood components from donors who were anti-HCV-nonreactive by first generation ELISA but whose serum later tested anti-HCV-reactive to a second generation ELISA. All these blood components were further tested for anti-HCV using a second-generation RIBA and for HCV RNA by polymerase chain reaction. Recipient sera were tested for HCV RNA prior to and following blood component infusion. Blood components from four donors were positive for HCV RNA. All recipients of HCV RNA-positive blood components became viremic on the first day tested post-infusion. In addition, two recipients of HCV RNA-negative blood components tested HCV RNA-positive both pre- and post-infusion. Viremia persisted up to the time of death or day 100 in five of the six patients who were HCV RNA-positive post-transplant. No HCV RNA-positive recipient developed symptomatic acute hepatitis, and only two had aminotransferase elevations consistent with chronic hepatitis. We conclude that HCV RNA-positivity in blood components accurately predicts transmission of virus. Infection with HCV did not adversely affect short-term patient outcome following bone marrow transplantation.

Seroprevalence to Bartonella quintana among patients at a community clinic in downtown Seattle

In 1993, an outbreak of 10 cases of Bartonella quintana bacteremia occurred among homeless, alcoholic, human immunodeficiency virus (HIV)-negative persons in Seattle. To estimate the prevalence of past exposure B. quintana among this population, a serosurvey was conducted in 1994 among patients at a downtown Seattle clinic. Microimmunofluorescent titers to B. quintana in 192 clinic patients were compared with titers in 199 age- and sex-matched Seattle volunteer blood donors. Titers > or = 64 were detected in 20% (39/192) of clinic patients compared with 2% (4/199) of blood donors (P<.001). Among clinic patients, alcohol abuse was independently associated in multivariate analysis with titers > or = 64 (odds ratio, 3.3; 95% confidence interval, 1.6-6.9). Of the 39 patients with B. quintana titers > or = 64, 24 (62%) also had titers > or = 64 to Bartonella henselae, indicating serologic cross-reactivity between Bartonella species. These results suggest that a substantial proportion of this indigent, inner-city Seattle population was infected with B. quintana.

Capacity of the store-regulator in maintaining iron balance

There is evidence that iron stores alter iron absorption to meet body iron needs. In this study, quantitative aspects of this regulation of iron balance are examined. Two male subjects, one with low and one with average iron stores, were given additional dietary iron over 500 days. Changes in iron stores were monitored by plasma ferritin measurements, and the ferritin estimate of stores was validated at the end of the study by bleeding to the point of iron deficiency. The subject with low iron stores increased his ferritin by 39 micrograms/L or 0.8 mg/day, whereas the subject with average iron stores had no significant change. It is concluded that the mechanism by which stores regulate food iron absorption has a capacity of about 1 mg/day, sufficient to meet usual physiological needs, with the exception of pregnancy, as well as the ability to resist increase in stores above normal despite an iron rich diet.

Guidelines for blood utilization review

Hospitals are required by accrediting agencies to perform blood utilization review. Specific areas that must be addressed are the ordering, distribution, handling, dispensing, and administration of blood components. Monitoring the effects of transfusion on patients is also required. The format of the review process and the criteria for appropriate blood utilization must be developed by each institution. This article provides examples of areas that can be reviewed and procedures that may be used. However, the suggested laboratory values must not be interpreted as defining indications or criteria for transfusion. Each transfusion committee, or its equivalent, is responsible for developing its own institutional blood utilization procedures and audit criteria. Review and approval by the medical staff prior to implementation are essential. The procedures must also be reviewed and revised on a regular basis.

Transfusion-transmitted viral infections other than hepatitis and human immunodeficiency virus infection. Cytomegalovirus, Epstein-Barr virus, human herpesvirus 6, and human parvovirus B19

During the last decade, there has been a sharp increase in the number of tests routinely used to screen all volunteer whole blood donations for evidence of transfusion-transmissible infection. These measures have had a dramatic effect on improvements in transfusion safety, especially as far as hepatitis viruses and the human immunodeficiency virus are concerned. Although all blood donations are not routinely screened for evidence of possible transmissibility of cytomegalovirus, some are, since there is now a clearer understanding of the categories of patients in whom this infection must be avoided. Recent studies have also pointed to a role for leukocyte filtration of transfusion products as an alternative to donor screening for selected patients at risk of cytomegalovirus infection. With regard to other viruses, knowledge about the relevance of Epstein-Barr virus, human herpesvirus 6, and parvovirus to blood product safety is incomplete. Until their pathogenicity, if any, in transfusion recipients is known, recommendations about special handling of blood products because of concern for these viruses is premature.

Recombinant immunoblot and polymerase chain reaction testing in volunteer whole blood donors screened by a multi-antigen assay for hepatitis C virus antibodies

The purpose of this study was to compare the results of supplementary testing of volunteer whole blood donors who had been screened by the first hepatitis C virus antibody assay licensed in the United States with results from donors screened by a newer, more sensitive, multi-antigen assay. In contrast to the earlier assay, the multi-antigen assay incorporates a recombinant hepatitis C virus antigen, c22-3, which is encoded by a structural region of the viral genome. Supplementary testing included a second-generation recombinant immunoblot assay and a highly sensitive polymerase chain reaction assay for evidence of hepatitis C virus genomic RNA. A comparison of supplementary test results reveals a higher percentage of donors screened by the newer assay to be indeterminate on recombinant immunoblot (34.4% vs. 6.4%, p < 0.05). Furthermore, polymerase chain reaction testing of donors with indeterminate blot results shows that 14 percent have evidence of viral RNA. For this reason, counseling of donors with indeterminate patterns on immunoblot must include informing them of the possibility that they are infected.

Promotion of high school blood donations: testing the efficacy of a videotaped intervention

"Life to Life," an 11-minute videotape based on social learning principles, was used by 10 blood centers in presentations to 4970 high school students one week before school blood drives. At each school, some students saw the videotape and others attended a blood center's customary presentation. Students also completed a brief questionnaire assessing donation attitudes, donation history, and intent to donate. The videotape accounted for a relative increase of 18.7 percent in donations even when other factors were not controlled for. Results were analyzed with logistic models and showed a consistently positive effect over all models used. For students who had never donated, the estimated odds ratio for actual donation (videotape:control) was 1.528. When the model included both type of presentation and ethnicity, the relative increase in donation over that after the blood centers' usual presentation was 69.8 percent for first-time donors. Among previous donors considered alone, the effect on donation was not significant. Whatever their donor history, students who viewed the videotape showed significantly more positive attitudes toward donation and had greater intention to donate than students who saw the blood centers' standard presentations. These results suggest that this videotape is a useful tool for recruitment of high school blood donors.

Reducing the risk for transfusion-transmitted cytomegalovirus infection

OBJECTIVE

To define the groups of patients at risk for transfusion-transmitted cytomegalovirus infection and to define the methods to reduce this risk.

DATA SOURCES

English-language publications on transfusion medicine.

STUDY SELECTION AND DATA EXTRACTION

Studies were selected that described cytomegalovirus infection in transfusion-dependent patients. Special attention was paid to reports that included observations about the prevalence and clinical manifestations of cytomegalovirus infection and recommendations for the prevention of infection.

DATA SYNTHESIS

Some patients with impaired immune responses who have never been exposed to cytomegalovirus are at risk for transfusion-transmitted cytomegalovirus infection. This infection, which is associated with substantial morbidity and mortality, can be avoided by additional screening of blood donors or by special processing of components for transfusion.

CONCLUSIONS

Transfusion products that are unlikely to transmit cytomegalovirus infection can be prepared by filtration to remove leukocytes or can be obtained by selecting donors who are seronegative for antibodies to cytomegalovirus. These products are indicated for certain groups of immunosuppressed patients, including pregnant women who are cytomegalovirus seronegative, premature infants of low birth weight who are born to cytomegalovirus-seronegative mothers, cytomegalovirus-seronegative recipients of allogeneic bone marrow transplants from cytomegalovirus-seronegative donors, and cytomegalovirus-seronegative patients with the acquired immunodeficiency syndrome (AIDS).

Use of leukocyte-depleted platelets and cytomegalovirus-seronegative red blood cells for prevention of primary cytomegalovirus infection after marrow transplant

Seventy-seven cytomegalovirus (CMV)-seronegative marrow transplant patients were randomized in a prospective controlled trial comparing the use of leukocyte-depleted platelets plus CMV-seronegative red blood cells with standard unscreened blood products for the prevention of primary CMV infection during the first 100 days after transplant. Eligible patients included CMV-seronegative patients undergoing autologous transplant or seronegative patients undergoing allogeneic transplant for aplastic anemia or non-hematologic malignancy who had seronegative marrow donors. Patients and marrow donors were serologically screened for CMV and randomized before conditioning for transplant and followed for CMV infection with weekly cultures of throat, urine, and blood and with weekly CMV serologies until day 100 after transplant. Leukocyte-depleted platelets were prepared by centrifugation, a procedure that removed greater than 99% of leukocytes. There were no CMV infections observed in 35 evaluable treatment patients compared with seven infections in 30 evaluable control patients (P = .0013). There was no statistically significant difference in the mean number of platelet concentrates in the treatment patients (164 concentrates) compared with the control patients (126 concentrates). Leukocyte-depleted platelets plus CMV-seronegative red blood cells are highly effective in preventing primary CMV infection after marrow transplant.

Transfusion therapy: associated risks and alternative approaches

Transfusion therapy has been the mainstay for treating the anemia of end-stage renal disease (ESRD). Recently, several factors, including the awareness of associated risks, especially the transmission of blood-borne diseases and the transient treatment effect with regard to reversal of anemic symptoms, have caused a reassessment of transfusion therapy. Recombinant human erythropoietin (epoetin) has emerged as the alternative treatment, capable of sustained reversal of anemia without the associated risks of transfusions. The result of epoetin therapy has been marked improvement in the quality of life of ESRD patients. However, the advent of this therapy has also changed the nurse's role in caring for ESRD patients, as new medical management issues are identified and supportive care is tailored to the individual patient.

Prevalence of human immunodeficiency virus type 1 p24 antigen in U.S. blood donors--an assessment of the efficacy of testing in donor screening. The HIV-Antigen Study Group

BACKGROUND

We performed a multicenter study in 1989 to determine whether screening whole-blood donors for human immunodeficiency virus type 1 (HIV-1) p24 antigen would improve transfusion safety by identifying carriers of the virus who are seronegative for HIV-1 antibody.

METHODS

More than 500,000 donations were tested at 13 U.S. blood centers with test kits from two manufacturers. Units found repeatedly reactive were retested in a central laboratory; if the results were positive, they were confirmed by a neutralization assay. A subgroup of units was also tested for HIV-1 by the polymerase chain reaction. Selected donors confirmed or not confirmed as having p24 antigen were contacted for follow-up interviews to identify risk factors and undergo retesting for HIV-1 markers.

RESULTS

Positive tests for p24 antigen were confirmed by neutralization in five donors (0.001 percent of all donations tested), all of whom were also positive for HIV-1 antibody and HIV-1 by polymerase chain reaction. Three of the antigen-positive donors had other markers of infectious disease that would have resulted in the exclusion of their blood; two had risk factors for HIV-1 that should have led to self-exclusion. Of 220 blood units with repeatedly reactive p24 antigen whose presence could not be confirmed by neutralization (0.04 percent of the donations studied), none were positive for HIV-1 antibody, HIV-1 by polymerase chain reaction (120 units tested), or virus culture (76 units tested)--attesting to the specificity of confirmatory neutralization.

CONCLUSIONS

The finding that no donation studied was positive for p24 antigen and negative for HIV-1 antibody suggests that screening donors for p24 antigen with tests of the current level of sensitivity would not add substantially to the safety of the U.S. blood supply.

Guidelines for transfusion support in patients undergoing coronary artery bypass grafting. Transfusion Practices Committee of the American Association of Blood Banks

We have reviewed the impact of evolving issues in coronary artery bypass grafting (CABG) on transfusion support for these patients. Issues include increased awareness of transfusion risks, reappraisal of traditional indicators triggering transfusion, and evolving alternatives to homologous blood transfusion such as autologous blood and pharmacologic therapy. These issues have been prompted by programs, such as the National Institutes of Health Consensus Conferences, to provide physicians with guidelines for appropriate use of blood components. However, evidence suggests that transfusion practice in coronary artery bypass grafting procedures remains variable and does not take into account the results of recently published clinical studies. We have therefore developed guidelines and recommendations for transfusion support in patients undergoing coronary artery bypass grafting. In summary, they are the following. 1. Institutions with coronary artery bypass grafting programs should establish a multidisciplinary approach to use a combination of interventions designed to minimize homologous blood exposure. 2. Prophylactic transfusion of plasma and platelets are of no benefit and therefore carry an unnecessary risk to the patient. 3. Special request products such as designated blood donation from first-degree relatives should not be used because of the risk of transfusion-associated graft versus host disease. 4. For support of intravascular volume, crystalloids or colloids should be used because they do not have the potential to transmit infection.

Hemolytic transfusion reaction due to interdonor kell incompatibility. Report of two cases and review of the literature

A 74-year-old man experienced an acute hemolytic reaction following transfusion of 4 units of red blood cells. The recipient was K negative, one of the transfused units was K positive, and another contained a previously undetected anti-K with an indirect antiglobulin titer of 512. Further investigation led to the discovery of a hemolytic transfusion reaction in a second K-negative patient who received a platelet transfusion containing 50 mL of plasma from the same donor. The clinical and serologic features of these two cases and five previously reported cases of hemolytic transfusion reaction due to interdonor Kell incompatibility are summarized.

HLA antibodies as a cause of false-positive reactions in screening enzyme immunoassays for antibodies to human T-lymphotropic virus type III

15,680 volunteer blood donors were screened by enzyme-linked immunosorbent assay (EIA) for antibodies to human T-lymphotropic virus Type III (HTLV-III). On at least two of three determinations, 0.37 percent were found to be reactive. When the first 38 of these samples were sent for repeat EIA and Western blot, the EIA was positive in 14. In only three of these 14 samples was the EIA result confirmed by Western blot. Eight of these eleven false-positive samples were from women who were found to have HLA antibodies. In seven of these women, the HLA antibodies were directed to Class II antigens expressed on the cell used to grow HTLV-III in the preparation of screening EIA kits. We conclude that HLA antibodies are an important cause of false-positive reactions in the screening test for HTLV-III antibody.

Transferrin saturation, plasma iron turnover, and transferrin uptake in normal humans

The relationship between plasma iron, transferrin saturation, and plasma iron turnover was studied in 53 normal subjects whose transferrin saturation varied between 17% and 57%, in 25 normal subjects whose transferrin saturation was increased by iron infusion to between 67% and 100%, and in five subjects with early untreated idiopathic hemochromatosis whose transferrin saturation was continually elevated to between 61% and 86%. The plasma iron turnover of all of these subjects ranged from 0.45 to 1.22 mg/dL whole blood/d. The mean values for the above-mentioned three groups were 0.71 +/- 0.17, 1.01 +/- 0.11, and 1.01 +/- 0.13 mg/dL whole blood/d, respectively. Most of this variation, estimated at 72% by regression analysis, was due to a direct relationship between transferrin saturation and plasma iron turnover. This effect was attributed to a competitive advantage of diferric over monoferric transferrin in delivering iron to tissues. This was confirmed by the demonstration of a more rapid clearance of diferric as compared to monoferric transferrin in an additional group of eight normal subjects. Calculations were made of the amount of transferrin reacting with membrane receptors per unit time. Allowance was made for the noncellular (extravascular) exchange and for the 4.2:1 preference of diferric over monoferric transferrin demonstrated in vitro. The amount of iron-bearing transferrin leaving the plasma to bind to tissue receptors for 53 subjects with a transferrin saturation between 17% and 57% was 71 +/- 13; for 25 subjects with a saturation from 67% to 100%, 72 +/- 12; and for five subjects with early idiopathic hemochromatosis, 82 +/- 11 mumol/L whole blood/d. There were no significant differences among these groups. These studies indicate that while the number of iron atoms delivered to the tissues increases with increasing plasma iron and transferrin saturation, the number of iron-bearing transferrin molecules that leave the plasma per unit time to bind to tissue receptors is relatively constant and within the limits studied, independent of transferrin saturation.

Supplementation of total parenteral nutrition solutions with ferrous citrate

Daily infusion of a total parenteral nutrition (TPN) formulation containing 1 liter of 5.5% Travasol provides less than 0.1 milligrams of iron. By comparison, a formulation which includes a liter of 10% Travamin provides 2 milligrams of iron per day. To meet iron requirements in patients infusing formulations containing Travasol, iron was added as ferrous citrate. In in virto experiments, 74% of this iron was available to transferrin. In seven patients in whom in vivo availability was tested by red cell incorporation, the mean availability was 81%. Ferrous citrate is recommended as a safe, effective additive to TPN solutions for adult patients requiring iron supplements.

Serum alanine aminotransferase in blood donors: activity distribution and effect of phenotype

Alanine aminotransferase (ALT) phenotype and serum activities were determined in 200 random volunteer blood donors. Serum enzyme activities were not significantly affected by the ALT phenotype (p greater than 0.1). Studies on 500 random volunteer blood donors showed significant differences in serum ALT levels between male and female donors (p less than 0.001). Elevated serum ALT levels were more commonly found in male donors; the frequency of male donors with levels of 45 IU/l or higher was 2.5 percent compared with 0.9 percent in female donors. The frequency of donors with serum ALT levels of 80 IU/l or higher was 0.6 percent of the total donor population sampled.

Iron absorption from maize (Zea mays) and sorghum (Sorghum vulgare) beer

1. Iron absorption from maize (Zea mays) and sorghum (Sorghum vulgare) beer was more than twelve-fold greater than from a gruel made from the constituents used to prepare the beer. 2. The effect of changes occurring during brewing were investigated. These changes include a decrease in the solid content, and the formation of 30 ml ethanol/1 and 5 ml lactic acid/1. 3. The presence of solid material was found to inhibit Fe absorption markedly, especially when the solid content was 100 g/l or more. 4. The presence of ethanol potentiated Fe absorption but the effect was only modest in gruels with a high solid content. 5. Fe absorption from a 2 ml lactic acid/l solution was four-fold greater than from a hydrochloric acid solution of the same pH. When lactic acid was added to a gruel containing 200 g solids/l the mean absorbtion rose from 0.4 to 1.2 %. 6. In a direct comparison, Fe absorption from beer was significantly better than from a gruel of similar pH containing lactic acid. 7. The results suggest that at least three factors are responsible for the enhanced Fe absorption from maize and sorghum beer. These include the removal of solids during fermentation and the presence of ethanol and of lactic acid in the final brew. 8. In order to reproduce the way in which beer is brewed domestically in Fe containers, a study was done in which beer was prepared in the presence of Fe wire. Under such circumstances Fe was rapidly dissolved and the final Fe concentration of the brew was 89 mg/l. However, the nature of the Fe-containing compound or compounds was not elucidated.

Anaemia, iron deficiency and exercise: extended studies in human subjects

1. Ventilation and cardiac frequency were measured during repeated treadmill exercise in three healthy subjects over 36 weeks, before, during and after iron-deficiency anaemia was produced and after iron treatment. The haemoglobin and 2,3-diphosphoglycerate concentrations and the oxygen-binding (P50) were measured. 2. There was an inverse relationship between the haemoglobin concentrations and the 2,3-diphosphoglycerate concentrations and the P50 values. 3. The mean cardiac frequencies during the fourth to tenth minutes of exercise showed a negative correlation with the haemoglobin concentrations in all three subjects, and the mean minute ventilations in two of them.

Iron absorption from rice meals cooked with fortified salt containing ferrous sulphate and ascorbic acid

1. Iron absorption from rice-containing meals was measured by red cell utilization of radioactive Fe in sixty-six volunteer multiparous Indian women.

2. In all the studies salt added during the cooking process was used as the carrier for supplemental inorganic Fe and ascorbic acid.

3. Intrinsic Fe in the rice and supplementary inorganic Fe were absorbed to the same extent, with a wide range of absorption values.

4. There was a striking difference between the mean absorption of a 3 mg dose of ferrous Fe given to fasting subjects in a solution containing 30 mg ascorbic acid and that of Fe in a rice meal (48.7 and 3.5% respectively).

5. When ascorbic acid was added during cooking there was a threefold increase in the absorption of both intrinsic Fe and supplementary Fe when a sufficient quantity (60 mg) was present.

6. It is concluded that the Fe nutrition of rice-eating communities could be improved significantly by the addition of ascorbic acid to the diet.

The effects of ascorbic acid supplementation on the absorption of iron in maize, wheat and soya

The absorption of iron from three staple vegetables was measured by the red cell utilization method in iron deficient subjects. The food iron had been labelled with 55Fe by the hydroponic cultivation method. In addition, 59Fe was added with or without carrier iron in the form of ferric ammonium citrate, prior to cooking. The constant relationship reported by others between the absorption of the two isotopes was confirmed, suggesting that the extrinsic iron and the food iron were absorbed from a common pool. The addition of ascorbic acid to maize porridge before cooking significantly enhanced the absorption of both the intrinsic and the added iron. However, no effect was noted with soya biscuits or with whole wheat bread (100% extraction). Evidence was obtained that these differences were due to the oxidative destruction of the ascorbic acid by the high temperatures required for baking. If, therefore, a feasible method were found for supplementing vegetable foodstuffs with ascorbic acid and inorganic iron, nutritional benefit would only be anticipated with uncooked or boiled foods.

Determination of lead in capillary blood using a paper punched disc atomic absorption technique. Application to the supervision of lead workers

Cernik, A. A., and Sayers, M. H. P. (1971).Brit. J. industr. Med.,28, 392-398. Determination of lead in capillary blood using a paper punched disc atomic absorption technique. Application to the supervision of lead workers. The presence of lead in blood is the most incontrovertible evidence of absorption but hitherto the need for venepuncture has limited its determination in the supervision of industrial workers. Micro-methods using atomic absorption spectrophotometry (AAS) have, however, made possible the development of a sufficiently reliable test using a drop of blood obtainable by ear prick for use in the field for screening purposes. A micro-sampling method by AAS is compared with a routine polarographic procedure (POL) using venous blood (corr. coeff. = 0·990). The pipetting of microlitres of blood can be eliminated by spotting the blood onto filter paper, allowing it to dry in air, and then using a punched-out standard disc of dried blood for analysis instead. Correlation of this method (PD) with the micro-sampling technique (AAS) is good (r=0·981). The PD method using capillary blood also correlates acceptably with the micromethod using venous blood (r = 0·913). A pilot field study using capillary blood estimated by the PD technique showed that with this method blood can be collected by ear prick in factories for monitoring workers in the lead industry, thus eliminating the need for routine venepuncture.