21 resultados para hemoglobin blood level

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Background: Studies investigating the association between glycated hemoglobin (HbA) level and mortality risk in diabetic patients receiving hemodialysis have shown conflicting results. 
Study Design: We conducted a systematic review and meta-analysis using MEDLINE, EMBASE, Web of Science, and the Cochrane Library. 
Setting & Population: Diabetic patients on maintenance hemodialysis therapy. 
Selection Criteria for Studies: Observational studies or randomized controlled trials investigating the association between HbA values and mortality risk. Study authors were asked to provide anonymized individual patient data or reanalyze results according to a standard template. 
Predictor: Single measurement or mean HbA values. Mean HbA values were calculated using all individual-patient HbA values during the follow-up period of contributing studies. 
Outcome: HR for mortality risk. 
Results: 10 studies (83,684 participants) were included: 9 observational studies and one secondary analysis of a randomized trial. After adjustment for confounders, patients with baseline HbA levels =8.5% (=69 mmol/mol) had increased mortality (7 studies; HR, 1.14; 95% CI, 1.09-1.19) compared with patients with HbA levels of 6.5%-7.4% (48-57 mmol/mol). Likewise, patients with a mean HbA value =8.5% also had a higher adjusted risk of mortality (6 studies; HR,1.29; 95% CI, 1.23-1.35). There was a small but nonsignificant increase in mortality associated with mean HbA levels =5.4% (=36 mmol/mol; 6 studies; HR, 1.09; 95% CI, 0.89-1.34). Sensitivity analyses in incident (=90 days of hemodialysis) and prevalent patients (>90 days of hemodialysis) showed a similar pattern. In incident patients, mean HbA levels =5.4% also were associated with increased mortality risk (4 studies; HR, 1.29; 95% CI, 1.23-1.35). 
Limitations: Observational study data and inability to adjust for diabetes type in all studies. 
Conclusions: Despite concerns about the utility of HbA measurement in hemodialysis patients, high levels (=8.5%) are associated with increased mortality risk. Very low HbA levels (=5.4%) also may be associated with increased mortality risk. 

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Rationale: Nonadherence to inhaled corticosteroid therapy (ICS) is a major contributor to poor control in difficult asthma, yet it is challenging to ascertain. Objectives: Identify a test for nonadherence using fractional exhaled nitric oxide (FENO) suppression after directly observed inhaled corticosteroid (DOICS) treatment. Methods: Difficult asthma patients with an elevated FENO (>45 ppb) were recruited as adherent (ICS prescription filling >80%) or nonadherent (filling <50%). They received 7 days of DOICS (budesonide 1,600 µg) and a test for nonadherence based on changes in FENO was developed. Using this test, clinic patients were prospectively classified as adherent or nonadherent and this was then validated against prescription filling records, prednisolone assay, and concordance interview. Measurements and Main Results: After 7 days of DOICS nonadherent (n = 9) compared with adherent subjects (n = 13) had a greater reduction in FENO to 47 ± 21% versus 79 ± 26% of baseline measurement (P = 0.003), which was also evident after 5 days (P = 0.02) and a FENO test for nonadherence (area under the curve = 0.86; 95% confidence interval, 0.68-1.00) was defined. Prospective validation in 40 subjects found the test identified 13 as nonadherent; eight confirmed nonadherence during interview (three of whom had excellent prescription filling but did not take medication), five denied nonadherence, two had poor inhaler technique (unintentional nonadherence), and one also denied nonadherence to prednisolone despite nonadherent blood level. Twenty-seven participants were adherent on testing, which was confirmed in 21. Five admitted poor ICS adherence but of these, four were adherent with oral steroids and one with omalizumab. Conclusions: FENO suppression after DOICS provides an objective test to distinguish adherent from nonadherent patients with difficult asthma. Clinical trial registered with www.clinicaltrials.gov (NCT 01219036). Copyright © 2012 by the American Thoracic Society.

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Lead (Pb) is a non-threshold toxin capable of inducing toxic effects at any blood level but availability of soil screening criteria for assessing potential health risks is limited. The oral bioaccessibility of Pb in 163 soil samples was attributed to sources through solubility estimation and domain identification. Samples were extracted following the Unified BARGE Method. Urban, mineralisation, peat and granite domains accounted for elevated Pb concentrations compared to rural samples. High Pb solubility explained moderate-high gastric (G) bioaccessible fractions throughout the study area. Higher maximum G concentrations were measured in urban (97.6 mg kg−1) and mineralisation (199.8 mg kg−1) domains. Higher average G concentrations occurred in mineralisation (36.4 mg kg−1) and granite (36.0 mg kg−1) domains. Findings suggest diffuse anthropogenic and widespread geogenic contamination could be capable of presenting health risks, having implications for land management decisions in jurisdictions where guidance advises these forms of pollution should not be regarded as contaminated land.

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The short-term systemic and renal hemodynamic effects of two stroma-free hemoglobin (SFH) solutions, one unmodified and the other modified by cross-linking, were examined in anesthetized rats after hemorrhagic hypotension. Both forms of SFH increased mean arterial pressure (MAP) and glomerular filtration rate (GFR) to baseline (prehemorrhage) values. The increase in MAP induced by unmodified SFH was greater than the increase in MAP caused by an albumin solution isoncotic to the unmodified SFH solution. Similarly, the increase in MAP caused by the modified SFH was also substantially greater than that induced by an albumin solution of comparable oncotic pressure to the modified SFH solution. Both unmodified and modified SFH increased GFR. As with MAP, the increase in GFR induced by both SFH solutions was greater than that associated with the oncotically matched albumin solutions. In separate experiments, the effects of nitric oxide (NO) inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) on MAP after hemorrhagic hypotension and subsequent infusion of unmodified SFH or albumin were also examined. In the albumin-infused rats, L-NAME increased MAP. In marked contrast, NO inhibition with L-NAME had no further effect on MAP when infused after SFH. We conclude that both unmodified and modified SFH solutions acutely improve MAP and GFR by the combined effects of intravascular volume expansion resulting from the colloid effect of the protein and by inactivation of NO.

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BACKGROUND: Hypertension and cognitive impairment are prevalent in older people. It is known that hypertension is a direct risk factor for vascular dementia and recent studies have suggested hypertension also impacts upon prevalence of Alzheimer's disease. The question is therefore whether treatment of hypertension lowers the rate of cognitive decline. OBJECTIVES: To assess the effects of blood pressure lowering treatments for the prevention of dementia and cognitive decline in patients with hypertension but no history of cerebrovascular disease. SEARCH STRATEGY: The trials were identified through a search of CDCIG's Specialised Register, CENTRAL, MEDLINE, EMBASE, PsycINFO and CINAHL on 27 April 2005. SELECTION CRITERIA: Randomized, double-blind, placebo controlled trials in which pharmacological or non-pharmacological interventions to lower blood pressure were given for at least six months. DATA COLLECTION AND ANALYSIS: Two independent reviewers assessed trial quality and extracted data. The following outcomes were assessed: incidence of dementia, cognitive change from baseline, blood pressure level, incidence and severity of side effects and quality of life. MAIN RESULTS: Three trials including 12,091 hypertensive subjects were identified. Average age was 72.8 years. Participants were recruited from industrialised countries. Mean blood pressure at entry across the studies was 170/84 mmHg. All trials instituted a stepped care approach to hypertension treatment, starting with a calcium-channel blocker, a diuretic or an angiotensin receptor blocker. The combined result of the three trials reporting incidence of dementia indicated no significant difference between treatment and placebo (Odds Ratio (OR) = 0.89, 95% CI 0.69, 1.16). Blood pressure reduction resulted in a 11% relative risk reduction of dementia in patients with no prior cerebrovascular disease but this effect was not statistically significant (p = 0.38) and there was considerable heterogeneity between the trials. The combined results from the two trials reporting change in Mini Mental State Examination (MMSE) did not indicate a benefit from treatment (Weighted Mean Difference (WMD) = 0.10, 95% CI -0.03, 0.23). Both systolic and diastolic blood pressure levels were reduced significantly in the two trials assessing this outcome (WMD = -7.53, 95% CI -8.28, -6.77 for systolic blood pressure, WMD = -3.87, 95% CI -4.25, -3.50 for diastolic blood pressure).Two trials reported adverse effects requiring discontinuation of treatment and the combined results indicated a significant benefit from placebo (OR = 1.18, 95% CI 1.06, 1.30). When analysed separately, however, more patients on placebo in SCOPE were likely to discontinue treatment due to side effects; the converse was true in SHEP 1991. Quality of life data could not be analysed in the three studies. There was difficulty with the control group in this review as many of the control subjects received antihypertensive treatment because their blood pressures exceeded pre-set values. In most cases the study became a comparison between the study drug against a usual antihypertensive regimen. AUTHORS' CONCLUSIONS: There was no convincing evidence from the trials identified that blood pressure lowering prevents the development of dementia or cognitive impairment in hypertensive patients with no apparent prior cerebrovascular disease. There were significant problems identified with analysing the data, however, due to the number of patients lost to follow-up and the number of placebo patients given active treatment. This introduced bias. More robust results may be obtained by analysing one year data to reduce differential drop-out or by conducting a meta-analysis using individual patient data.

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The use of blood spot collection cards is a simple way to obtain specimens for analysis of drugs for the purpose of therapeutic drug monitoring, assessing adherence to medications and preventing toxicity in routine clinical setting. We describe the development and validation of a microanalytical technique for the determination of metformin from dried blood spots. The method is based on reversed phase high-performance liquid chromatography with ultraviolet detection. Drug recovery in the developed method was found to be more than 84%. The limits of detection and quantification were calculated to be to be 90 and 150 ng/ml, respectively. The intraday and interday precision (measured by CV%) was always less than 9%. The accuracy (measured by relative error, %) was always less than 12%. Stability analysis showed that metformin is stable for at least 2 months when stored at -70 degrees C. The small volume of blood required (10 mu L), combined with the simplicity of the analytical technique makes this a useful procedure for monitoring metformin concentrations in routine clinical settings. The method is currently being applied to the analysis of blood spots taken from diabetic patients to assess adherence to medications and relationship between metformin level and metabolic control of diabetes. (c) 2006 Elsevier B.V. All rights reserved.

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An array of schistosome endoproteases involved in the digestion of host hemoglobin to absorbable peptides has been described, but the exoprotease responsible for catabolising these peptides to amino acids has yet to be identified. By searching the public databases we found that Schistosoma mansoni and Schistosoma japonicum express a gene encoding a member of the M17 family of leucine aminopeptidases (LAPs). A functional recombinant S. mansoni LAP produced in insect cells shared biochemical properties, including pH optimum for activity, substrate specificity and reliance on metal cations for activity, with the major aminopeptidase activity in soluble extracts of adult worms. The pH range in which the enzyme functions and the lack of a signal peptide indicate that the enzyme functions intracellularly. Immunolocalisation studies showed that the S. mansoni LAP is synthesised in the gastrodermal cells surrounding the gut lumen. Accordingly, we propose that peptides generated in the lumen of the schistosome gut are absorbed into the gastrodermal cells and are cleaved by LAP to free amino acids before being distributed to the internal tissues of the parasite. Since LAP was also localised to the surface tegument it may play an additional role in surface membrane re-modelling. (C) 2004 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

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Although approximately 95% of patients with polycythemia vera (PV) harbor the V617F mutation in JAK2 exon 14, several mutations in exon 12 have been described in the remaining patients. We conducted a European collaborative study to define the molecular and clinical features of patients harboring these mutations. Overall, 106 PVs were recruited and 17 different mutations identified. Irrespective of the mutation, two-thirds of patients had isolated erythrocytosis, whereas the remaining subjects had erythrocytosis plus leukocytosis and/or thrombocytosis. Compared with JAK2 (V617F)-positive PV patients, those with exon 12 mutations had significantly higher hemoglobin level and lower platelet and leukocyte counts at diagnosis but similar incidences of thrombosis, myelofibrosis, leukemia, and death. In a multivariable analysis, age more than 60 years and prior thrombosis predicted thrombosis. These findings suggest that, despite the phenotypical difference, the outcome of JAK2 exon 12 mutations-positive PV is similar to that of JAK2 (V617F)positive PV. (Blood. 2011; 117(10):2813-2816)

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Background: This is an update of a previous review (McGuinness 2006). Hypertension and cognitive impairment are prevalent in older people. Hypertension is a direct risk factor for vascular dementia (VaD) and recent studies have suggested hypertension impacts upon prevalence of Alzheimer's disease (AD). Therefore does treatment of hypertension prevent cognitive decline?
Objectives: To assess the effects of blood pressure lowering treatments for the prevention of dementia and cognitive decline in patients with hypertension but no history of cerebrovascular disease.
Search strategy: The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS as well as many trials databases and grey literature sources were searched on 13 February 2008 using the terms: hypertens$ OR anti-hypertens$. Selection criteria: Randomized, double-blind, placebo controlled trials in which pharmacological or non-pharmacological interventions to lower blood pressure were given for at least six months.
Data collection and analysis: Two independent reviewers assessed trial quality and extracted data. The following outcomes were assessed: incidence of dementia, cognitive change from baseline, blood pressure level, incidence and severity of side effects and quality of life.
Main results: Four trials including 15,936 hypertensive subjects were identified. Average age was 75.4 years. Mean blood pressure at entry across the studies was 171/86 mmHg. The combined result of the four trials reporting incidence of dementia indicated no significant difference between treatment and placebo (236/7767 versus 259/7660, Odds Ratio (OR) = 0.89, 95% CI 0.74, 1.07) and there was considerable heterogeneity between the trials. The combined results from the three trials reporting change in Mini Mental State Examination (MMSE) did not indicate a benefit from treatment (Weighted Mean Difference (WMD) = 0.42, 95%CI 0.30, 0.53). Both systolic and diastolic blood pressure levels were reduced significantly in the three trials assessing this outcome (WMD = -10.22, 95% CI -10.78, -9.66 for systolic blood pressure, WMD = -4.28, 95% CI -4.58, -3.98 for diastolic blood pressure). Three trials reported adverse effects requiring discontinuation of treatment and the combined results indicated no significant difference (OR = 1.01, 95% CI 0.92, 1.11). When analysed separately, however, more patients on placebo in Syst Eur 1997 were likely to discontinue treatment due to side effects; the converse was true in SHEP 1991. Quality of life data could not be analysed in the four studies. Analysis of the included studies in this review was problematic as many of the control subjects received antihypertensive treatment because their blood pressures exceeded pre-set values. In most cases the study became a comparison between the study drug against a usual antihypertensive regimen.
Authors' conclusions: There is no convincing evidence fromthe trials identified that blood pressure lowering in late-life prevents the development of dementia or cognitive impairment in hypertensive patients with no apparent prior cerebrovascular disease. There were significant problems identified with analysing the data, however, due to the number of patients lost to follow-up and the number of placebo patients who received active treatment. This introduced bias. More robust results may be obtained by conducting a meta-analysis using individual patient data.

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Background: There is growing interest in the potential utility of molecular diagnostics in improving the detection of life-threatening infection (sepsis). LightCycler® SeptiFast is a multipathogen probebased real-time PCR system targeting DNA sequences of bacteria and fungi present in blood samples within a few hours. We report here the protocol of the first systematic review of published clinical diagnostic accuracy studies of this technology when compared with blood culture in the setting of suspected sepsis. Methods/design: Data sources: the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects (DARE), the Health Technology Assessment Database (HTA), the NHS Economic Evaluation Database (NHSEED), The Cochrane Library, MEDLINE, EMBASE, ISI Web of Science, BIOSIS Previews, MEDION and the Aggressive Research Intelligence Facility Database (ARIF). Study selection: diagnostic accuracy studies that compare the real-time PCR technology with standard culture results performed on a patient's blood sample during the management of sepsis. Data extraction: three reviewers, working independently, will determine the level of evidence, methodological quality and a standard data set relating to demographics and diagnostic accuracy metrics for each study. Statistical analysis/data synthesis: heterogeneity of studies will be investigated using a coupled forest plot of sensitivity and specificity and a scatter plot in Receiver Operator Characteristic (ROC) space. Bivariate model method will be used to estimate summary sensitivity and specificity. The authors will investigate reporting biases using funnel plots based on effective sample size and regression tests of asymmetry. Subgroup analyses are planned for adults, children and infection setting (hospital vs community) if sufficient data are uncovered. Dissemination: Recommendations will be made to the Department of Health (as part of an open-access HTA report) as to whether the real-time PCR technology has sufficient clinical diagnostic accuracy potential to move forward to efficacy testing during the provision of routine clinical care.

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Anemia is a symptom associated with cognitive dysfunction and is diagnosed if the hemoglobin level of a blood sample is too low. The clinical impact of chronically low hemoglobin level may be insuf?cient
brain oxygenation, which may result in a decline in cognitive functioning. Previous studies have provided evidence of decrements in cognitive functioning associated with anemia across various disease processes, but few have investigated the association between cognitive dysfunction and hemoglobin level in patients with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS). As this population is inherently anemic, studying these patients allowed for an exploration of cognitive changes at mild, moderate, and severe levels of anemia. This investigation explored cutoff points for hemoglobin at which cognitive decline may occur. Findings showed decrements in cognitive functioning occurring at hemoglobin levels of 10 g/dL or below. Performance on measures of word retrieval, attention, and ?ne motor function was most affected which suggests fronto-temporal lobe dysfunction. Results provided evidence as to a hemoglobin cutoff point below which cognitive function may be affected in patients with AML and MDS. This cutoff value may provide a clinical marker at which cognitive testing and therapeutic interventions could be utilized to improve patients’ cognitive function, level of fatigue and overall quality of life.

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Committees worldwide have set almost identical folate recommendations for the prevention of the first occurrence of neural tube defects (NTDs). We evaluate these recommendations by reviewing the results of intervention studies that examined the response of red blood cell folate to altered folate intake. Three options are suggested to achieve the extra 400 mu g folic acid/d being recommended by the official committees: increased intake of folate-rich foods, dietary folic acid supplementation, and folic acid fortification of food. A significant increase in foods naturally rich in folates was shown to be a relatively ineffective means of increasing red blood cell folate status in women compared with equivalent intakes of folic acid-fortified food, presumably because the synthetic form of the vitamin is more stable and more bioavailable. Although folic acid supplements are highly effective in optimizing folate status, supplementation is not an effective strategy for the primary prevention of NTDs because of poor compliance. Thus, food fortification is seen by many as the only option likely to succeed. Mandatory folic acid fortification of grain products was introduced recently in the United States at a level projected to provide an additional mean intake of 100 mu g folic acid/d, but some feel that this policy does not go far enough. A recent clinical trial predicted that the additional intake of folic acid in the United States will reduce NTDs by >20%, whereas 200 mu g/d would be highly protective and is the dose also shown to be optimal in lowering plasma homocysteine, with possible benefits in preventing cardiovascular disease. Thus, an amount lower than the current target of an extra 400 mu g/d may be sufficient to increase red blood cell folate to concentrations associated with the lowest risk of NTDs, but further investigation is warranted to establish the optimal amount.

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We have investigated the relationship between erythropoietin (Epo) and pH, PaO2 and haematocrit in 100 cord blood samples obtained at Caesarean section prior to labour. Of 82 term (> 37 weeks) infants, 64 were appropriately grown (10th-90th centiles), and their mean cord serum Epo and cord blood Epo was 23 +/- 8 mU/ml (mean +/- SD). Strong inverse correlations were found between cord serum Epo and cord blood pH (r = -0.74; p <0.0001), and between cord serum Epo and cord blood PaO2 (r = -0.55; p <0.0001), but not between cord serum Epo and cord haematocrit (r = 0.02; p <0.9). For the 18 preterm babies (gestation 32.4 +/- 4.1 weeks, birth weight 1,820 +/- 476 g), the Epo level was 36 +/- 8 mU/ml, which was not significantly greater than for the term babies. Strong inverse correlations were again found between Epo and pH (r = -0.87; p <0.0001) and Epo and PaO2 (r = -0.69; p <0.002). Babies from complicated pregnancies (intra-uterine growth retardation, pre-eclampsia, antepartum haemorrhage, diabetes mellitus and fetal distress) tended to have higher Epo levels. Thirteen babies had Epo levels > 40 mU/ml, and 11 (85%) of these required neonatal intensive care. Cord serum Epo correlates better with oxygen tension and pH at birth than with fetal growth and haematocrit, which are measures of chronic stress to the fetus.

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Biomarkers are conventionally defined as "biological molecules that represent health and disease states." They typically are measured in readily available body fluids (blood or urine), lie outside the causal pathway, are able to detect subclinical disease, and are used to monitor clinical and subclinical disease burden and response to treatments. Biomarkers can be "direct" endpoints of the disease itself, or "indirect" or surrogate endpoints. New technologies (such as metabolomics, proteomics, genomics) bring a wealth of opportunity to develop new biomarkers. Other new technologies enable the development of nonmolecular, functional, or biophysical tissue-based biomarkers. Diabetes mellitus is a complex disease affecting almost every tissue and organ system, with metabolic ramifications extending far beyond impaired glucose metabolism. Biomarkers may reflect the presence and severity of hyperglycemia (ie, diabetes itself) or the presence and severity of the vascular complications of diabetes. Illustrative examples are considered in this brief review. In blood, hemoglobin A1c (HbA1c) may be considered as a biomarker for the presence and severity of hyperglycemia, implying diabetes or prediabetes, or, over time, as a "biomarker for a risk factor," ie, hyperglycemia as a risk factor for diabetic retinopathy, nephropathy, and other vascular complications of diabetes. In tissues, glycation and oxidative stress resulting from hyperglycemia and dyslipidemia lead to widespread modification of biomolecules by advanced glycation end products (AGEs). Some of these altered species may serve as biomarkers, whereas others may lie in the causal pathway for vascular damage. New noninvasive technologies can detect tissue damage mediated by AGE formation: these include indirect measures such as pulse wave analysis (a marker of vascular dysfunction) and more direct markers such as skin autofluorescence (a marker of long-term accumulation of AGEs). In the future, we can be optimistic that new blood and tissue-based biomarkers will enable the detection, prevention, and treatment of diabetes and its complications long before overt disease develops.

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Epidemiological studies show that elevated plasma levels of advanced glycation end products (AGEs) are associated with diabetes, kidney disease, and heart disease. Thus AGEs have been used as disease progression markers. However, the effects of variations in biological sample processing procedures on the level of AGEs in plasma/serum samples have not been investigated. The objective of this investigation was to assess the effect of variations in blood sample collection on measured Ne_(carboxy-methyl)lysine (CML), the best characterised AGE, and its homolog, Ne_(carboxyethyl)lysine (CEL). The investigation examined the effect on CML and CEL of different blood collection tubes, inclusion of a stabilising cocktail, effect of freeze thaw cycles, different storage times and temperatures, and effects of delaying centrifugation on a pooled sample from healthy volunteers. CML and CEL were measured in extracted samples by ultra_performance liquid chromatography-tandem mass spectrometry. Median CML and CEL ranged from 0.132 to 0.140 mM/M lys and from 0.053 to 0.060 mM/M lys, respectively. No significant difference was shown CML or CEL in plasma/serum samples. Therefore samples collected as part of epidemiological studies that do not undergo specific sample treatment at collection are suitable for measuring CML and CEL.