Seasonal changes in red blood cell parameters

Empowering frail older adults: multicomponent elastic-band exercises and BCAA supplementation unleash physical health and preserve haematological biomarkers

The effectiveness of Branched Chain Amino Acids (BCAAs) supplementation on enhancing exercise performance in both young and older adults remains a topic of debate. Recent research suggests that BCAAs combined with regular exercise might have an impact on human erythropoiesis, blood dynamics, and iron homeostasis. Given the increasing longevity of the global population, it is crucial to investigate the potential benefits of BCAA supplementation and regular exercise as non-pharmacological interventions for improving the overall health of frail older adults. To assess the influence of a 40-week multicomponent exercise intervention (MEP) combined BCCA supplementation on the haematological indicators of frail older adults (83-93 years old) residing in nursing homes. A prospective, naturalistic, controlled clinical trial employing an intervention-washout-intervention was conducted for this purpose. The study included four experimental groups: MEP plus BCAA supplementation (MEP + BCAA, n = 8), MEP only (n = 7), BCAA supplementation only (n = 7), and control group non exercising (CG, n = 13). Fried's physical frailty (PF) protocol was employed to stratify the participants. Additionally, the assessment included the evaluation of nutritional status, comorbidities, and anthropometric measurements. Among the several haematological markers examined, only mean cellular Haemoglobin Concentration (MCH) [F = 4.09; p < 0.03] and Mean Cell haemoglobin Concentration (MCHC) [F = 10, 323; p < 0,0001] showed significant effects of time group. Our findings demonstrate that a long-term intervention with BCAA plus MEP did not lead to significant alterations in the haematological profile. An 8-week withdrawal from interventions did not affect the frailty status in the MEP and MEP + BCAA groups, whereas the control group exhibited an increase in PF status. The findings, demonstrating the potential pro-immune effect and maintenance of MCH and MCHC levels, highlight the relevance of incorporating exercise and nutritional strategies to promote healthy aging. This study contributes to the achievement of the United Nations Sustainable Development Goals 3 (good health and well-being) and 10 (reduced Inequalities) for all.

Seasonal Heat Acclimatisation in Healthy Adults: A Systematic Review

Background

Physiological heat adaptations can be induced following various protocols that use either artificially controlled (i.e. acclimation) or naturally occurring (i.e. acclimatisation) environments. During the summer months in seasonal climates, adequate exposure to outdoor environmental heat stress should lead to transient seasonal heat acclimatisation.

Objectives

The aim of the systematic review was to assess the available literature and characterise seasonal heat acclimatisation during the summer months and identify key factors that influence the magnitude of adaptation.

Eligibility Criteria

English language, full-text articles that assessed seasonal heat acclimatisation on the same sample of healthy adults a minimum of 3 months apart were included.

Data Sources

Studies were identified using first- and second-order search terms in the databases MEDLINE, SPORTDiscus, CINAHL Plus with Full Text, Scopus and Cochrane, with the last search taking place on 15 July 2021.

Risk of Bias

Studies were independently assessed by two authors for the risk of bias using a modified version of the McMaster critical review form.

Data Extraction

Data for the following outcome variables were extracted: participant age, sex, body mass, height, body fat percentage, maximal oxygen uptake, time spent exercising outdoors (i.e. intensity, duration, environmental conditions), heat response test (i.e. protocol, time between tests), core temperature, skin temperature, heart rate, whole-body sweat loss, whole-body and local sweat rate, sweat sodium concentration, skin blood flow and plasma volume changes.

Results

Twenty-nine studies were included in this systematic review, including 561 participants across eight countries with a mean summer daytime wet-bulb globe temperature (WBGT) of 24.9 °C (range: 19.5–29.8 °C). Two studies reported a reduction in resting core temperature (0.16 °C; p < 0.05), 11 reported an increased sweat rate (range: 0.03–0.53 L·h⁻¹; p < 0.05), two observed a reduced heart rate during a heat response test (range: 3–8 beats·min⁻¹; p < 0.05), and six noted a reduced sweat sodium concentration (range: − 22 to − 59%; p < 0.05) following summer. The adaptations were associated with a mean summer WBGT of 25.2 °C (range: 19.6–28.7 °C).

Limitations

The available studies primarily focussed on healthy male adults and demonstrated large differences in the reporting of factors that influence the development of seasonal heat acclimatisation, namely, exposure time and duration, exercise task and environmental conditions.

Conclusions

Seasonal heat acclimatisation is induced across various climates in healthy adults. The magnitude of adaptation is dependent on a combination of environmental and physical activity characteristics. Providing environmental conditions are conducive to adaptation, the duration and intensity of outdoor physical activity, along with the timing of exposures, can influence seasonal heat acclimatisation. Future research should ensure the documentation of these factors to allow for a better characterisation of seasonal heat acclimatisation.

PROSPERO Registration

CRD42020201883.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-022-01677-0.

Removal of the influence of plasma volume fluctuations for the athlete biological passport and stability of haematological variables in active women taking oral contraception

The haematological module of the athlete biological passport (ABP) monitors longitudinal haematological variations that could be indicative of blood manipulation. This study applied a multi‐parametric model previously validated in elite cyclists to compare inferred and actual PV variations, whereas the potential influence of the oral contraceptive pill (OCP) cycle on the ABP blood biomarkers and plasma volume (PV) in 14 physically active women taking OCPs was also investigated. Blood and serum samples were collected each week for 8 weeks, and the ABP haematological variables were determined according to the World Anti‐Doping Agency guidelines. Transferrin (sTFN), ferritin (FERR), albumin (ALB), calcium (Ca), creatinine (CRE), total protein (TP) and low‐density lipoprotein (LDL) were additionally computed as ‘volume‐sensitive’ variables in a multivariate analysis to determine individual estimations of PV variations. Actual PV variations were indirectly measured using a validated carbon monoxide rebreathing method. We hypothesised ABP markers to be stable during a standard OCP cycle and estimated PV variations similar to measured PV variations. Measured PV variations were in good agreement with the predictions and allowed to explain an atypical passport finding (ATPF). The ABP biomarkers, Hbmass and PV were stable over 8 weeks. Significant differences occurred only between Week 7 and Week 1, with lower levels of haemoglobin concentration ([Hb]), haematocrit (HCT) and red blood cell count (RBC)(−4.4%, p < 0.01; −5.1%, p < 0.01; −5.2%, p < 0.01) and higher levels of PV at week 7 (+9%, p = 0.05). We thus concluded that estimating PV variations may help interpret individual ABP haematological profiles in women.

Deep longitudinal multiomics profiling reveals two biological seasonal patterns in California

The influence of seasons on biological processes is poorly understood. In order to identify biological seasonal patterns based on diverse molecular data, rather than calendar dates, we performed a deep longitudinal multiomics profiling of 105 individuals over 4 years. Here, we report more than 1000 seasonal variations in omics analytes and clinical measures. The different molecules group into two major seasonal patterns which correlate with peaks in late spring and late fall/early winter in California. The two patterns are enriched for molecules involved in human biological processes such as inflammation, immunity, cardiovascular health, as well as neurological and psychiatric conditions. Lastly, we identify molecules and microbes that demonstrate different seasonal patterns in insulin sensitive and insulin resistant individuals. The results of our study have important implications in healthcare and highlight the value of considering seasonality when assessing population wide health risk and management.

Photoperiodic Effects on Diurnal Rhythms in Cell Numbers of Peripheral Leukocytes in Domestic Pigs

The photoperiod is known to modulate immune cell number and function and is regarded essential for seasonal disease susceptibility. In addition, diurnal variations in the immune system are regarded important for immune competence. Whereas few studies investigated the influence of season, none investigated the specific effect of the photoperiod on these diurnal immune rhythms until now. Therefore, the present study compared diurnal rhythms in cell numbers of peripheral leukocyte types in domestic pigs held either under long day conditions (LD) or short day conditions (SD). Cosinor analyses of cell numbers of various peripheral leukocyte subtypes investigated over periods of 50 h revealed distinct photoperiodic differences in diurnal immune rhythms. Relative amplitudes of cell numbers of total leukocytes, NK cells, T cells, and monocytes in blood were higher under SD than LD. In addition, cell counts of total leukocytes, NK cells, T cells including various T cell subtypes, and eosinophils peaked earlier relative to the time of lights-on under SD than LD. In contrast, diurnal rhythms of neutrophil counts did not show photoperiodic differences. Mesor values did not differ in any leukocyte type. Generalized linear mixed model analyses revealed associations of leukocyte counts with plasma cortisol concentration and activity behavior in most investigated cell types. Moreover, the present study demonstrated photoperiodic effects on diurnal rhythms in plasma cortisol concentrations and activity behavior, which is in agreement with human and primate studies. The results of the present study imply stronger rhythmicity in leukocyte counts in general under SD. Common intrinsic mechanisms seem to regulate photoperiodic effects on diurnal rhythms in leukocyte counts, except for neutrophils, in domestic pigs. Our results reveal considerable insights into the regulation of immune rhythms in diurnally active species.

Comparisons of Blood Parameters, Red Blood Cell Deformability and Circulating Nitric Oxide Between Males and Females Considering Hormonal Contraception: A Longitudinal Gender Study

Red blood cell (RBC) deformability is an important determinant of the microcirculation. It is influenced by various hematological parameters but also by nitric oxide (NO) which is produced in RBC from L-arginine by RBC-NO synthase. Longitudinal studies on blood profile, deformability at rest and NO levels but also differences between males and females (±hormonal contraception; HC) are less known so far. The study thus aimed to investigate RBC deformability, RBC NO species (nitrite, RxNO), RBC L-arginine concentration and basal blood parameters in males and females (±HC) as a function of time. RBC deformability was measured at rest once per week and the remaining parameters were measured once per month, respectively. A second experiment aimed to daily measure RBC deformability and 17β-estradiol in Female ± HC during a whole menstruation cycle to investigate a possible relation of the two parameters. Measured parameters showed low week-to-week variation and remained constant during study period. However, RBC deformability increased in Female + HC during study period possibly because of increasing training volume of the participants. Overall, results indicate gender differences in hematological parameters with higher RBC parameters (RBC count, hematocrit, hemoglobin concentration) in males compared to females. Differences were also observed between the female groups with Females - HC showing lower number of RBC but higher MCV and hematocrit compared to Females + HC. RBC deformability was highest in Females - HC which might be related to permanent higher estradiol levels and/or higher RBC NO levels because RBC nitrite and RBC RxNO concentrations were also highest in Females-HC. Results of the second experiment also suggest higher RBC deformability in Female - HC because of higher estradiol concentrations. L-arginine levels known to be related to RBC NO production were comparable in all groups. In conclusion, hematological, hemorheological and NO related parameters show gender differences. In particular, RBC deformability is affected by training volume and RBC estradiol concentrations. The results add new information on the complex regulation of RBC function which might help to better understand the role of RBC in the microcirculation.

Seasonal Variations of Complete Blood Count and Inflammatory Biomarkers in the US Population - Analysis of NHANES Data

Background

Recent studies reported seasonal differences in gene expression in white blood cells, adipose tissue, and inflammatory biomarkers of the immune system. There is no data on the seasonal variations of these biomarkers in the US general population of both children and adults. Then aim of this study is to explore the seasonal trends in complete blood count (CBC), and C-reactive protein (CRP) in a large non-institutionalized US population.

Methods

Seven cross-sectional data collected in the National Health and Nutrition Examination Survey (NHANES) during 1999–2012 were aggregated; participants reporting recent use of prescribed steroids, chemotherapy, immunomodulators and antibiotics were excluded. Linear regression models were used to compare levels of CBC and CRP between winter-spring (November-April) and summer-fall (May-October), adjusting for demographics, personal behavioral factors, and chronic disease conditions.

Results

A total of 27,478 children and 36,644 adults (≥18 years) were included in the study. Levels of neutrophils, white blood cell count (WBC), and CRP were higher in winter-spring than summer-fall (p≤0.05). Red blood cell components were lower in winter-spring than in summer-fall, while the opposite was seen for platelets.

Conclusions

This large population-based study found notable seasonal variations in blood cell composition and inflammatory biomarkers, with a more pro-inflammatory immune system seen in winter-spring than summer-fall. The red blood cell patterns could have implications for the observed cardio-vascular seasonality.

Decline in the prevalence of anaemia among children of pre-school age after implementation of wheat flour fortification with multiple micronutrients in Jordan

Objective

To examine changes in the prevalence of anaemia and its correlates among children of pre-school age after implementation of wheat flour fortification with multiple micronutrients in Jordan.

Design

Retrospective analysis of the data from two repeated national cross-sectional panels of pre-school children.

Setting

The two surveys were conducted in 2007 and 2009, 16–20 months and 34–36 months, respectively, after implementation of wheat flour fortification with multiple micronutrients in Jordan. Anaemia was considered if Hb level was <11 g/dl. An anaemia prevalence of ≥40 % was considered a severe public health problem, while that of 20–39·9 % was considered a moderate public health problem.

Subjects

A total of 3789 and 3447 children aged 6–59 months tested in 2007 and 2009, respectively.

Results

The prevalence of anaemia in pre-school children declined from 40·4 % in 2007 to 33·9 % in 2009 (adjusted OR=0·74; P<0·001). The decline in the prevalence in 2009 as compared with 2007 was more pronounced among children aged >24 months (−13·7 points), children living in urban areas (−8·0 points), children from rich households (−9·0 points), children who had never been breast-fed (−17·0 points) and well-nourished children (−6·8 points). In both surveys, presence of childhood anaemia was strongly associated with child age ≤24 months, living in poor households, breast-feeding for ≥6 months, malnourishment, poor maternal education and maternal anaemia.

Conclusions

The public health problem of childhood anaemia declined from severe in 2007 to moderate in 2009, after the implementation of wheat flour fortification with multiple micronutrients in Jordan.

Summertime dosage-dependent hypersensitivity to an angiotensin II receptor blocker

Background

Summertime dips in blood pressure (BP), both in normotensive and hypertensive subjects, are well known. However, the dips are small and are not related to particular forms or doses of antihypertensive medication. Nevertheless it is the practice in some quarters to decrease antihypertensive medication in summer, and/or to increase in winter. Large scale studies being inconclusive, there are calls for long-term examination of the relationship between environmental temperature and blood pressure in single individuals under medication.

Case presentation

While analyzing data from a subject whose BP had been controlled for a decade with the angiotensin-II receptor blocker losartan, an extreme, dosage-dependent, summertime dip came to light. Downward dosage adjustment appeared essential and may have prevented hypotension-related pathology.

Conclusion

The benefits of aggressive medication (the “J curve” phenomenon) being debated, the possibility of seasonal hypersensitivity, perhaps explicable in terms of differential signaling by countervailing receptors, should be taken into account when considering dosage adjustments in hypertensive subjects.

Seasonal effects on gene expression

Many health conditions, ranging from psychiatric disorders to cardiovascular disease, display notable seasonal variation in severity and onset. In order to understand the molecular processes underlying this phenomenon, we have examined seasonal variation in the transcriptome of 606 healthy individuals. We show that 74 transcripts associated with a 12-month seasonal cycle were enriched for processes involved in DNA repair and binding. An additional 94 transcripts demonstrated significant seasonal variability that was largely influenced by blood cell count levels. These transcripts were enriched for immune function, protein production, and specific cellular markers for lymphocytes. Accordingly, cell counts for erythrocytes, platelets, neutrophils, monocytes, and CD19 cells demonstrated significant association with a 12-month seasonal cycle. These results demonstrate that seasonal variation is an important environmental regulator of gene expression and blood cell composition. Notable changes in leukocyte counts and genes involved in immune function indicate that immune cell physiology varies throughout the year in healthy individuals.

Within-subject haemoglobin variation in elite athletes: a longitudinal investigation of 13 887 haemoglobin concentration readings

The Athlete Biological Passport (ABP) estimates individualized reference ranges for key blood markers, such as haemoglobin concentration ([Hb]), using predetermined population mean, between- and within-subject variances. Here, we aim to reassess previously published estimates for within-subject [Hb] variance and determine whether sex-, analyzer-, sport-, or season-specific values are required. Our reference population contains 7723 male (mean ± SD, 22.3 ± 4.6 years of age) and 6164 female (21.6 ± 4.3) athlete observations from 49 sports. [Hb] was calculated using one of three cytometers; Bayer-H3 (1997-1999, n = 4554), ADVIA-120 (1999-2010, n = 8636) and Sysmex XT-2000i (2010-2012, n = 697). The final model was a linear mixed model for [Hb] with analyzer (H3, ADVIA, Sysmex), sex (male, female), sport (power-endurance, endurance, skill, team, disabled and non-athletes), season (summer, winter), and the interaction between sex and sport as fixed effects and athlete as a random effect. The model included an exponential correlation structure to allow for within-subject autocorrelation, and allowed different within-subject variances for each sport. Within-subject [Hb] variance (g(2) /L(2) ) was significantly less for power endurance (35.09, 95% CI 33.50 to 36.76), disabled (25.82, 95% CI 21.71 to 35.28) and non-athletes (34.30, 95% CI 28.53 to 35.87) than for endurance (40.35, 95% CI 39.62 to 47.22) and team sports (38.70, 95% CI 37.68 to 39.76) athletes. No new evidence was found to justify adjusting the current within-subject [Hb] variance estimate.

Assessment of hematological profiles of adult male athletes from two different air pollutant zones of West Bengal, India

Health effects from air pollution are severe concern of today's world. The study was undertaken to assess the effects of air pollution on hematological profiles of trained and untrained males of West Bengal. The sample consisted of 60 sprinters, 60 footballers, and 120 untrained males, subdivided into two groups from two zones, namely, Tollygunge and Sonarpur. Suspended particulate matter (SPM), respirable particulate matter (RPM), oxides of sulfur (SOx), and oxides of nitrogen (NOx) of ambient air were monitored for both zones. Height and weight of all the subjects were measured. Venous blood sample was drawn from the cubital vein, and the red blood cell count (TC), packed cell volume (PCV), hemoglobin (Hb) concentration, mean corpuscular volume (MCV), and mean corpuscular hemoglobin concentration (MCHC) were determined by standard methods. Results revealed that SPM, RPM, SOx, and NOx concentrations were significantly higher in the Tollygunge area than Sonarpur. TC, PCV, and Hb concentration of untrained males were significantly higher than footballers in both regions but no significant difference were observed when compared with sprinters, except the Hb concentration in the Tollygunge zone. On the other hand, all hematological parameters of both trained and untrained males were significantly higher in the Sonarpur area than Tollygunge. It was concluded that environmental air pollutants might influence hematological profile adversely both in trained and sedentary males. However, further investigation in this area is needed.

Variation in hematologic and serum biochemical values of belugas (Delphinapterus leucas) under managed care

Blood analytes are critical for evaluating the general health of cetacean populations, so it is important to understand the intrinsic variability of hematology and serum chemistry values. Previous studies have reported data for follow-up periods of several years in managed and wild populations, but studies over long periods of time (> 20 yr) have not been reported. The study objective was to identify the influences of partitioning characteristics on hematology and serum chemistry analytes of apparently healthy managed beluga (Delphinapterus leucas). Blood values from 31 managed belugas, at three facilities, collected over 22 yr, were assessed for seasonal variation and aging trends, and evaluated for biologic variation among and within individuals. Linear mixed effects models assessed the relationship between the analytes and sex, age, season, facility location, ambient air temperature, and photoperiod. Sex differences in analytes and associations with increasing age were observed. Seasonal variation was observed for hemoglobin, hematocrit, mean corpuscular volume, monocytes, alkaline phosphatase, total bilirubin, cholesterol, and triglycerides. Facilities were associated with larger effects on analyte values compared to other covariates, whereas age, sex, and ambient temperature had smaller effects compared to facility and season. Present findings provide important baseline information for future health monitoring efforts. Interpretation of blood analytes and animal health in managed and wild populations over time is aided by having available typical levels for the species and reference intervals for the degree to which individual animals vary from the species average and from their own baseline levels during long-term monitoring.

Predicting hemoglobin levels in whole blood donors using transition models and mixed effects models

Background

To optimize the planning of blood donations but also to continue motivating the volunteers it is important to streamline the practical organization of the timing of donations. While donors are asked to return for donation after a suitable period, still a relevant proportion of blood donors is deferred from donation each year due to a too low hemoglobin level. Rejection of donation may demotivate the candidate donor and implies an inefficient planning of the donation process. Hence, it is important to predict the future hemoglobin level to improve the planning of donors’ visits to the blood bank.

Methods

The development of the hemoglobin prediction rule is based on longitudinal (panel) data from blood donations collected by Sanquin (the only blood product collecting and supplying organization in the Netherlands). We explored and contrasted two popular statistical models, i.e. the transition (autoregressive) model and the mixed effects model as plausible models to account for the dependence among subsequent hemoglobin levels within a donor.

Results

The predictors of the future hemoglobin level are age, season, hemoglobin levels at the previous visits, and a binary variable indicating whether a donation was made at the previous visit. Based on cross-validation, the areas under the receiver operating characteristic curve (AUCs) for male donors are 0.83 and 0.81 for the transition model and the mixed effects model, respectively; for female donors we obtained AUC values of 0.73 and 0.72 for the transition model and the mixed effects model, respectively.

Conclusion

We showed that the transition models and the mixed effects models provide a much better prediction compared to a multiple linear regression model. In general, the transition model provides a somewhat better prediction than the mixed effects model, especially at high visit numbers. In addition, the transition model offers a better trade-off between sensitivity and specificity when varying the cut-off values for eligibility in predicted values. Hence transition models make the prediction of hemoglobin level more precise and may lead to less deferral from donation in the future.

Capillary versus venous haemoglobin determination in the assessment of healthy blood donors

BACKGROUND AND OBJECTIVES

To determine the accuracy of fingerstick haemoglobin assessment in blood donors, the performance of a portable haemoglobinometer (HemoCue Hb 201+) was prospectively compared with that of an automated haematology analyzer (Cell-Dyn 4000). Haemoglobin values obtained by the latter were used as the 'true' result.

MATERIAL AND METHODS

Capillary fingerstick samples were assayed by HemoCue in 150 donors. Fingerstick samples from two sites, one on each hand, were obtained from a subset of 50 subjects. Concurrent venous samples were tested using both HemoCue and Cell-Dyn devices.

RESULTS

Capillary haemoglobin values (HemoCue) were significantly greater than venous haemoglobin values (HemoCue), which in turn were significantly greater than venous haemoglobin values by Cell-Dyn (mean ± SD: 14.05 ± 1.51, 13.89 ± 1.31, 13.62 ± 1.23, respectively; P < 0.01 for all comparisons among groups). Nine donors (6%) passed haemoglobin screening criteria (≥ 12.5 g/dl) by capillary HemoCue, but were deferred by Cell-Dyn values (false-pass). Five donors (3%) were deferred by capillary sampling, but passed by Cell-Dyn (false-fail). Substantial variability in repeated fingerstick HemoCue results was seen (mean haemoglobin 13.72 vs. 13.70 g/dl, absolute mean difference between paired samples 0.76 g/dl). Hand dominance was not a factor.

CONCLUSIONS

Capillary samples assessed via a portable device yielded higher haemoglobin values than venous samples assessed on an automated analyzer. False-pass and false-fail rates were low and acceptable in the donor screening setting, with 'true' values not differing by a clinically significant degree from threshold values used to assess acceptability for blood donation.

Association of mild anemia with hospitalization and mortality in the elderly: the Health and Anemia population-based study

BACKGROUND

Mild anemia is a frequent laboratory finding in the elderly usually disregarded in everyday practice as an innocent bystander. The aim of the present population-based study was to prospectively investigate the association of mild grade anemia with hospitalization and mortality.

DESIGN AND METHODS

A prospective population-based study of all 65 to 84 year old residents in Biella, Italy was performed between 2003 and 2007. Data from a total of 7,536 elderly with blood tests were available to estimate mortality; full health information available to evaluate health-related outcomes was available for 4,501 of these elderly subjects. Mild grade anemia was defined as a hemoglobin concentration between 10.0 and 11.9 g/dL in women and between 10.0 and 12.9 g/dL in men.

RESULTS

The risk of hospitalization in the 3 years following recruitment was higher among the mildly anemic elderly subjects than among subjects who were not anemic (adjusted hazard ratio: 1.32; 95% confidence interval: 1.09-1.60). Mortality risk in the following 3.5 years was also higher among the mildly anemic elderly (adjusted hazard ratio: 1.86; 95% confidence interval: 1.34-2.53). Similar results were found when slightly elevating the lower limit of normal hemoglobin concentration to 12.2 g/dL in women and to 13.2 g/dL in men. The risk of mortality was significantly increased in mild anemia of chronic disease but not in that due to beta-thalassemia minor.

CONCLUSIONS

After controlling for many potential confounders, mild grade anemia was found to be prospectively associated with clinically relevant outcomes such as increased risk of hospitalization and all-cause mortality. Whether raising hemoglobin concentrations can reduce the risks associated with mild anemia should be tested in controlled clinical trials.

Seasonal influences on hemoglobin levels and deferral rates in whole-blood and plasma donors

BACKGROUND

Indications exist that deferral rates in blood donors are highest in summer. However, a detailed quantitative analysis is not available. The association between Hb values, deferral rates, and daily temperatures was investigated in a large data set of blood donors.

STUDY DESIGN AND METHODS

The study population consisted of both plasma and whole-blood donors from the southeast region of the Netherlands. Individual Hb levels and other examination data between January 2002 and December 2004 were extracted from the donor file. Data on daily maximum temperatures were related to Hb levels and Hb deferrals. Results are reported separately for plasma and whole-blood donors as well as for men and women.

RESULTS

Data were available from 106,398 whole blood donors and 6983 plasma donors, resulting in data of more than 600,000 examinations. Hb levels decreased with increasing daily temperature. Highest deferral rates were observed in summer months, which were consistent over the several groups and over the three years. The highest Hb deferral of 11.1 percent was observed for female whole-blood donors on days with a maximum temperature of 25 degrees and above. In all four donor categories a gradual increase with temperature was observed with 1.7-2.2 times higher deferral rates on hot days (> or = 25 degrees C) compared to cold days (<5 degrees C).

CONCLUSION

A clear seasonal pattern in Hb levels and in the percentage of Hb deferrals was observed. The observed seasonal effect could not be explained by differences in donor characteristics. Our observations might have practical implications for donor management.

Seasonal variation of pretransfusion hemoglobin levels in patients with thalassemia major

Patients with thalassemia major often report that they do not maintain their usual pretransfusion hemoglobin concentration during the summer season. We collected 3977 pretransfusion hemoglobin values, amount of blood transfused, and intertransfusion intervals for 94 patients with thalassemia major from 4 centers worldwide. We also assessed the hematocrits of blood donors, the hemoglobin content of units transfused in one center, and the local mean monthly temperatures during the periods of data collection. Pretransfusion hemoglobin levels were significantly lower during the summer in all centers except the one center where monthly temperatures have the least variation throughout the year. A similar relationship to temperature was observed for the hematocrits of blood donors and the hemoglobin content of donor units. This study confirms that pretransfusion hemoglobin levels in patients with thalassemia major are lower in the summertime. Possible mechanisms include expansion of plasma volume with resultant hemodilution in the patient and lower hemoglobin content in donor blood.

Haematocrit: within-subject and seasonal variation

This review was undertaken, concerning within-subject biological variation and seasonal variation of haematocrit in normal healthy adults and athletes, to find the limits for natural, intra-individual variation in haematocrit values. The terminology and calculations followed well defined theories, from the field of laboratory medicine, about biological variation. Based on results from 12 studies of 638 normal healthy adults, and which used a sampling interval of 1 day to 1-2 months, the coefficient of within-subject biological variation of haematocrit is 3%. The normal within-subject biological variation (3%) and analytical variation (3%) may explain a relative change of approximately 12% (95% level) [e.g. a change from 0.42-0.47] between two successive haematocrit values, measured with a time interval between 1 day and 1-2 months, in a normal healthy adult. Partly due to haemodilution in warm weather, haematocrit often has a seasonal variation in normal healthy adults; based on results from 18 studies of 24 793 participants, the population mean is approximately 3% lower in summer than winter. Population mean values that are 7% lower in summer than winter have been found in some studies, although no seasonal effect may also be seen, especially in temperate climates. If haematocrit values are sampled at yearly peak and trough time points, with intervals of up to 6 months, a 15% relative change (95% level) can be seen in a normal healthy adult; e.g. a change from 0.42-0.48. Published values for haematocrit in athletes are scarce. It is known that the haematocrit value is influenced by training, especially in the first weeks before a new steady-state is reached. Theoretically, the biological variation in athletes could therefore be greater than in normal individuals. Based on two references addressing the biological variation of haematocrit in athletes, however, the above results are also valid for athletes. Further studies, both in the short term and throughout the seasons, are recommended about the natural variation of haematocrit in athletes.

Hematological indices in elite cyclists

BACKGROUND

Blood testing is a major concern in sports. Sporting federations have introduced cut-off values for hematological variables to limit blood manipulations. To date, no reference margins have been established to adjust single- or multivariable blood tests to the exercise adapted blood cell system of athletes. We studied hemoglobin (Hb), hematocrit (Hct), blood cell variables and changes in vascular volumes in male and female national team cyclists to evaluate the influence of exercise on these variables and the results of blood tests, and to estimate normal ranges in athletes for blood tests.

METHODS

1628 blood samples of 169 male and 55 female athletes were considered. Samples were analyzed automatically, blood cell indices and vascular volumes were calculated. Overall averages and seasonal differences were estimated.

RESULTS

Hb-average was: 15.4 +/- 0.8 g dL(-1) for male and 13.9 +/- 0.7 g dL(-1) for female cyclists, Hct: 45 +/- 2.9% and 40.7 +/- 2.7%. Blood variables and vascular volumes showed significant seasonal changes. 1-6% of all samples were found above the currently used limits for blood testing. This is in accordance with the data from the normal population. Nevertheless, EPO misuse or blood manipulations cannot totally be excluded.

CONCLUSION

Athletes display seasonal adaptations in their blood profile which should be considered in testing regulations. The presented data might be used as reference values for indirect single- and multivariable blood tests.

Particulate air pollution and the blood

BACKGROUND

Particulate air pollution has been associated with excess deaths from, and increases in hospital admissions for, cardiovascular disease among older people. A study was undertaken to determine whether this may be a consequence of alterations in the blood, secondary to pulmonary inflammation caused by the action of fine particles on alveolar cells, by repeatedly measuring haematological factors in older people and relating them to measurements of exposure to airborne particles.

METHODS

One hundred and twelve individuals aged 60+ years in two UK cities provided repeated blood samples over 18 months, 108 providing the maximum of 12 samples. Estimates of individual exposure to particles of less than 10 microm diameter (PM(10)), derived from a mathematical model based on activity diaries and comparative measurements of PM(10) at multiple sites and during a variety of activities, were made for each three day period prior to blood sampling. The relationships between blood values and estimates of both personal exposure and city centre measurements of PM(10) were investigated by analysis of covariance, adjusting for city, season, temperature, and repeated individual measurements.

RESULTS

Estimated personal exposure to PM(10) over the previous three days showed negative correlations with haemoglobin concentration, packed cell volume (PCV), and red blood cell count (p<0.001), and with platelets and factor VII levels (p<0.05). The changes in red cell indices persisted after adjustment for plasma albumin in a sample of 60 of the subjects. City centre PM(10) measurements over three days also showed negative correlations with haemoglobin and red cell count (p<0.001) and with PCV and fibrinogen (p<0.05), the relationship with haemoglobin persisting after adjustment for albumin. C reactive protein levels showed a positive association with city centre measurements of PM(10) (p<0.01). Based on a linear relationship, the estimated change in haemoglobin associated with an alteration in particle concentration of 100 microg/m(3) is estimated to have been 0.44 g/dl (95% CI 0.62 to 0.26) for personal PM(10) and 0.73 g/dl (95% CI 1.11 to 0.36) for city centre PM(10) measurements.

CONCLUSIONS

This investigation is the first to estimate personal exposures to PM(10) and to demonstrate associations between haematological indices and air pollution. The changes in haemoglobin adjusted for albumin suggest that inhalation of some component of PM(10) may cause sequestration of red cells in the circulation. We propose that an action of such particles either on lung endothelial cells or on erythrocytes themselves may be responsible for changing red cell adhesiveness. Peripheral sequestration of red cells offers an explanation for the observed cardiovascular effects of particulate air pollution.

Seasonal changes in calcitropic hormones in Israeli men

Seasonal changes in calcitropic hormones might be expected, being that dietary calcium intake may differ with fluctuations in climate and temperature, and vitamin D is diet- and sunlight-dependent. While there are studies on elderly subjects, prospective data on younger men is limited. The objective of this study was to clarify possible seasonal changes in homeostatic regulators of calcium in Israeli men aged 25-64 years. The study was a prospective follow-up analysis of data collected during June-August 1995 and 1996 (summer) and January March 1995 and 1996 (winter). Subjects were ninety-five industrial male employees with and without occupational lead exposure. The main outcome measures were summer and winter serum concentrations of parathyroid hormone (PTH), 25-hydroxyvitamin D (25-OH-D), and 1,25-dihydroxyvitamin D (calcitriol). Summer and winter values of PTH were similar (38.2 and 39.8 ng/l, respectively). 25-OH-D levels were significantly higher in summer (32.8 ng/ml) than in winter (25.4 ng/ml) after controlling for possible confounders (p < 0.0001). Calcitriol levels were significantly higher in summer (79.1 pmol/l) than in winter (73.5 pmol/l) in univariate analyses, but not after controlling for possible confounders. We conclude that healthy men show considerable seasonal changes in 25-OH-D levels even in Israel, a relatively sunny country all the year round. Summer values of 25-OH-D, were 35% higher than in winter. These fluctuations should be taken into account during evaluation of pathological conditions and in research. Given an adequate diet and vitamin D status there are no seasonal variations in PTH or in calcitriol levels.

The laboratory assessment of iron status--an update

The description by Ramsay in 1957 of a practical way of determining the total iron binding capacity of serum (a measure of transferrin concentration) provided a diagnostic test for both iron deficiency and iron overload. Since 1957 the introduction of the assay for serum ferritin (in 1972) has made it possible to assess the levels of storage iron in normal subjects and assays for free erythrocyte protoporphyrin and the circulating transferrin receptor methods to evaluate iron supply for erythropoiesis. In 1957 iron metabolism in man was already well understood but its evaluation relied on measurement of tissue iron concentrations and the use of radioisotopes of iron to measure rates of erythropoiesis. The evaluation can now be carried out using the various blood assays along with the measurement of haemoglobin concentration but interpretation of the measurements in disease still requires an understanding of the way in which these measures are influenced by pathological processes.