Capillary Samples Research Articles

Validation of point-of-care tests used at in-home assessments among older adults in primary care

Background Diagnosing acute disease in older adults is challenged by vague and atypical symptoms. Point-of-care tests (POCTs) at home may improve diagnostics and clinical decision-making. We compared various POCT devices to routine testing in acutely ill older adults to assess their clinical reliability. Methods We enrolled participants aged 65+ years requiring acute in-home assessment with signs of acute conditions. Venous and capillary blood samples were collected and analysed on-site using POCT, while identical samples were transported and analysed in a routine laboratory. Agreement between POCT and laboratory testing was assessed using scatter plots with linear regression, Pearson’s correlation coefficient (PCC), limits of agreement, and Bland-Altman plots. Misclassification rates were calculated based on clinically meaningful cut-offs to assess POCT’s clinical reliability. Results We included 100 participants with a mean age of 81.6 (±8.4 SD) years. Strong correlation was found between POCT and routine measurements (PCC: 0.76–0.94 for capillary samples and 0.85–0.98 for venous samples). Venous samples showed higher PCC than capillary, except for neutrophils (0.93 for capillary, 0.89 for venous). Misclassification occurred in capillary samples for haemoglobin (10/62) and total WBC (6/50), while in venous samples, misclassification was observed for haemoglobin (4/54), total WBC (4/50), K+ (5/47), urea (5/47), and creatinine (3/42). No misclassification was observed for Na+. Conclusion POCT provides acceptable, clinically reliable measurements in acutely ill older adults, potentially enhancing diagnostics and treatments during in-home assessment. Venous blood testing is preferable due to a lower misclassification rate, but capillary blood remains a pragmatic alternative, despite higher variation and inaccuracy.

Validating the Use of Continuous Glucose Monitors With Nondiabetic Recreational Runners.

Continuous glucose monitors (CGMs) are becoming increasingly popular among endurance athletes despite unconfirmed accuracy. We assessed the concurrent validity of the FreeStyle Libre 2 worn on 2 different sites at rest, during steady-state running, and postprandial. Thirteen nondiabetic, well-trained recreational runners (age = 40 [8]y, maximal aerobic oxygen consumption = 46.1 [6.4]mL·kg-1·min-1) wore a CGM on the upper arm and chest while treadmill running for 30, 60, and 90minutes at intensities corresponding to 50%, 60%, and 70% of maximal aerobic oxygen consumption, respectively. Glucose was measured by manually scanning CGMs and obtaining a finger-prick capillary blood glucose sample. Mean absolute relative difference, time in range, and continuous glucose Clarke error grid analysis were used to compare paired CGM and blood glucose readings. Across all intensities of steady-state running, we found a mean absolute relative difference of 13.8 (10.9) for the arm and 11.4 (9.0) for the chest. The coefficient of variation exceeded 70%. Approximately 47% of arm and 50% of chest paired glucose measurements had an absolute difference ≤10%. Continuous glucose Clarke error grid analysis indicated 99.8% (arm) and 99.6% (chest) CGM data fell in clinically acceptable zones A and B. Time-in-range analysis showed reduced accuracy at lower glucose levels. However, CGMs accurately detected trends in mean glucose readings over time. CGMs are not valid for point glucose monitoring but appear to be valid for monitoring glucose trends during steady-state exercise. Accuracy is similar for arm and chest. Further research is needed to determine whether CGMs can detect important events such as hypoglycemia during exercise.

GC-MS uncovers unique metabolic markers of drug-resistant epilepsy in capillary but not venous dried blood spots

This study compared the effectiveness of capillary dried blood spots (DBS) versus venous DBS in detecting metabolic changes related to drug-resistant epilepsy (DRE). DBS samples were collected from 142 epilepsy patients (58 drug-resistant, 84 drug-responsive) via venipuncture or fingerstick capillary sampling. Metabolomic analysis using gas chromatography-mass spectrometry compared DBS metabolite profiles between the two groups. While venous DBS profiles showed no distinct patterns, capillary DBS profiles revealed clustering patterns in principal components analysis, with the first two principal components explaining 14.5%, and 13.5% of the total variance, respectively. Orthogonal PLS-DA confirmed group discrimination (R2Y=0.989, Q2=0.742). Drug-resistant patients exhibited elevated capillary DBS levels of glutamine, pyruvic acid, and serine, and decreased palmitic acid compared to drug-responsive patients. Pathway analysis revealed disruptions in amino acid metabolism, neurotransmission, and cellular energy regulation. Elevated glutamine levels may contribute to an imbalance between excitatory glutamate and inhibitory GABA neurotransmission, key factors in epileptogenesis and drug resistance. Capillary DBS, likely enriched with arterial blood supply to the brain, appears to better capture central nervous system metabolic disturbances compared to venous DBS containing systemic contributions. This minimally invasive capillary DBS approach offers effective metabolic profiling of brain conditions like DRE, for monitoring disease progression and treatment response, enhancing personalized patient management in epilepsy.

Single-Cell Lipidomics: An Automated and Accessible Microfluidic Workflow Validated by Capillary Sampling.

We report the first demonstration of a microfluidics-based approach to measure lipids in single living cells using widely available liquid chromatography mass spectrometry (LC-MS) instrumentation. The method enables the rapid sorting of live cells into liquid chambers formed on standard Petri dishes and their subsequent dispensing into vials for analysis using LC-MS. This approach facilitates automated sampling, data acquisition, and analysis and carries the additional advantage of chromatographic separation, aimed at reducing matrix effects present in shotgun lipidomics approaches. We demonstrate that our method detects comparable numbers of features at around 200 lipids in populations of single cells versus established live single-cell capillary sampling methods and with greater throughput, albeit with the loss of spatial resolution. We also show the importance of optimization steps in addressing challenges from lipid contamination, especially in blanks, and demonstrate a 75% increase in the number of lipids identified. This work opens up a novel, accessible, and high-throughput way to obtain single-cell lipid profiles and also serves as an important validation of single-cell lipidomics through the use of different sampling methods.

Capillary drops, capillary pooled, and venous blood samples for determining hemoglobin concentration using HemoCue: A measurement system analysis.

Several external and internal factors can affect the performance and variability of Hemoglobin concentration [Hb] measurements using HemoCue, and documentation on the contribution of different sources of [Hb] variation is limited. We used an experimental repeated measurements design with nine randomly selected participants, three HemoCue devices, and three trained field workers. HemoCue measurements for all samples were repeated three times. The [Hb] measurement system considers four sources of error: 1) HemoCue devices, 2) field workers, 3) between individuals, and 4) within individuals. A concordance analysis was used to assess accuracy and precision, and a linear mixed model was used to estimate mean differences (bias) from blood specimens, anticoagulants, and to estimate the contribution of the 4 sources of error to [Hb] measurements. Positive mean [Hb] differences were found: 1.34 g/dL for capillary drops, 0.81 g/dL for pooled capillary blood samples, 0.756 g/dL for venous blood stored with EDTA, and 0.911 g/dL for venous blood stored with heparin. The mean [Hb] difference for venous blood with EDTA was used as a correction factor for all results measured using a HemoCue. After adjustment, capillary drops showed a mean difference of 0.585 g/dL, and pooled capillary samples were not significantly different. The individual variability was 95.8% of total variance, HemoCue devices contributed 2.1% of measurement error, field staff contributed 0.4%, and the residual was 1.7%. The HemoCue [Hb] measurement system is reliable in controlled environments, with a small measurement error of 4.2%.

Comparison of Microcapillary Blood Sampling Devices for Use in Anti-Doping.

Blood collection is an important facet of anti-doping testing, forming the basis of the hematological module of the athlete biological passport (ABP). Presently, whole blood is collected via venepucture under standardized conditions, in accordance with the World Anti-doping Agency's International Standard for Testing and Investigations (ISTI). Advances in capillary whole blood collection technology now afford the ability to collect microvolumetric capillary whole blood from the upper arm (or other suitable vascular location such as the abdomen) that is "needle-free" and virtually painless. Previous work has demonstrated the suitability and feasibility of capillary whole blood compared with venous using the Tasso+ device. Recently, other microcapillary devices have received FDA approval increasing the options available to the anti-doping community. The present study extends previous work, by collecting microliter capillary whole blood samples via two different FDA approved devices (RedDrop and the Tasso+ device) to compare with venous blood collected simultaneously. Ten participants provided three matched blood samples (2× capillary and 1× venous) in accordance with WADA ABP guidelines for blood sample collection, for a total of 30 samples. Capillary samples from both devices showed excellent laboratory agreement with venous blood for all CBC parameters, with the exception of platelets. Excellent laboratory agreement was also observed between the two microcapillary collection devices. Irrespective of the device, microcapillary blood collection provides a valid alternative to venous blood collection for ABP purposes.

A study to determine a capillary alternative to the gold standard oral glucose tolerance test - Protocol

Type 1 diabetes (T1D) is a chronic condition caused by the immune destruction of the pancreatic beta cells. T1D has recognised asymptomatic pre-clinical stages, providing an opportunity for early diagnosis, education and treatment which may delay the onset of symptoms. The oral glucose tolerance test (OGTT) is the gold standard method to stage and monitor early-stage T1D, which can be poorly tolerated and may contribute to marked loss to follow-up. Our study aims to test the accuracy, feasibility, and acceptability of a capillary alternative (‘GTT@home’ test kit) to the gold standard OGTT. We will invite 45 children and young people (CYP) across the spectrum of glycaemia with or without diabetes, from established research platforms or clinical care, to have a standard 2-hour OGTT, with capillary samples collected alongside their venous samples, at 0 and 120 minutes. A subgroup (n=20) will also have 60-minute capillary and venous samples collected. We will also invite 45 CYP from established research platforms, who are known to have two or more islet autoantibodies and are not on insulin, to undergo a capillary OGTT at home, using the GTT@home kit. We will assess the agreement of capillary and venous glucose and measure diagnostic accuracy by calculating the sensitivity and specificity of capillary measures at established diagnostic thresholds (fasting [5.6 mmol/L, 7.0 mmol/L], 60 minutes post glucose load [11.1 mmol/L] and 120 minutes post glucose load [7.8 mmol/L and 11.1 mmol/L]), using venous glucose as the gold standard. These studies will inform our understanding of whether the GTT@home device can be used in CYP in routine clinical care.

Maternal Anemia during Pregnancy and Infant Birth Outcomes: A Prospective Cohort Study in Eastern Maharashtra, India

BackgroundAnemia during pregnancy may be associated with poor infant outcomes, although its consequences may vary based on etiology and timing. ObjectivesWe examined the associations between anemia and anemia-related biomarkers during pregnancy and infant outcomes [birthweight, gestational age at birth, birthweight-for-gestational age percentile, and infant hemoglobin (Hb) at 6 wk of age] in Nagpur, Eastern Maharashtra, India. MethodsWe conducted a prospective cohort study of 200 pregnant women. In the first trimester, venous blood was collected to assess Hb via cyanmethemoglobin analysis, micronutrient status (ferritin, vitamin B12, and folate), and inflammation (C-reactive protein). Hb was also assessed in capillary samples using a hemoglobinometer in the first and third trimesters for mothers and at 6 wk for infants. Associations were assessed using generalized linear models controlling for background characteristics. ResultsIn the first trimester, high (compared with normal) venous Hb was significantly associated with lower gestational age at birth [β: −1.0 wk, 95% confidence interval (CI): −1.9, −0.2] and higher birthweight-for-gestational age percentile (β: 20.1, 95% CI: 9.0, 31.2). Mild anemia, moderate anemia, and high (compared with normal) capillary Hb were significantly associated with lower birthweight (β: −147.7 g, 95% CI: −243.4, −51.7; β: −77.7 g, 95% CI: −123.9, −31.4; and β: −236.0 g, 95% CI: −478.0, −48.1) and birthweight-for-gestational age percentile (β: −7.3, 95% CI: −13.7, −0.9; β: −8.4, 95% CI: −14.1, −2.8; and β: −8.9, 95% CI: −15.9, −1.9). Higher serum ferritin was significantly associated with higher birthweight (β: 2.0 g, 95% CI: 0.1, 3.9) and gestational age at birth (β: 0.01 wk, 95% CI: 0.00, 0.01). In the third trimester, mild anemia was significantly associated with lower gestational age at birth (β: −0.5 wk, 95% CI: −0.7, −0.3). ConclusionsAssociations between maternal anemia during pregnancy and infant outcomes were mixed indicating further studies are needed to better understand these relationships.

A-343 Novel In-Line Hemolysis Detection on a Blood Gas Analyzer for Capillary Samples

Abstract Background Point-of-care (POC) blood gas and electrolyte analyzers utilizing whole blood as the predominant sample type are blinded by the presence of hemolysis until today. Moreover, capillary samples are particularly vulnerable to in-vitro hemolysis due to excessive force applied during sample collection. Here, we introduce the GEM Premier 7000 with iQM3 (GEM 7000) which incorporates automatic, in-line hemolysis detection in capillary blood gas samples without a need for additional sample volume or reagents. Methods The hemolysis detection module which is integrated into the disposable GEM cartridge uses acoustophoretic technology and photometric measurements to detect hemolysis in whole blood. In GEM 7000, hemolysis of ≥ 116 mg/dL was found to have significant interference with potassium results. A hemolysis flag is presented as the degree of hemolysis: none (0 - 50 and 51 - 115), mild (116 - 200 and 201 - 300), moderate (301 - 400), and gross (≥401). Due to volume limitations with native capillary samples and challenges in assessing hemolysis levels with a comparator assay, venous blood spiked volumetrically with hemolysate and transferred to capillary devices was used to verify the hemolysis flag performance. An agreement analysis was performed using the Roche cobas hemolysis value. The device's (GEM 7000) ability to flag hemolyzed capillary samples is demonstrated in a simulated clinical setting using native and contrived fingerstick capillary samples. Results Hemolysis verification with transferred capillary samples demonstrated that 98.2% (274/279) of samples were correctly flagged based on the cobas hemolysis value of spiked hemoglobin. Hemolysis in the native capillary samples (N = 235) was primarily distributed in the 0-50 mg/dL range. Additionally, native capillary samples altered using vigorous flea mixing (> 1 minute) showed hemolysis distribution over a wide hemolysis degree (none to gross), and their potassium results were flagged accordingly. Conclusions By providing integrated hemolysis detection in capillary blood sample measurements, the GEM Premier 7000 with iQM3 system can provide quality and confidence in the clinical interpretation of critical results such as potassium.

A-319 Capillary Blood Collection for Egg-cellent Reproductive Insights

Abstract Background In the United States, an estimated 13% of women between the ages of 15 and 49 years, experience impaired reproductive potential (fecundity). Assessment of fecundity typically requires an in-person physician visit and venous blood collection to evaluate hormone levels and identify potential reproductive health conditions. Exploring less invasive, at-home sampling options could offer couples insights into their personal reproductive abilities, providing peace of mind and aiding in family planning. Methods Capillary blood, obtained using the Tasso®+ capillary blood collection device coupled with a BD Microtainer® serum tube, was utilized for measurements of analytes associated with female fecundity (follicle stimulating hormone, luteinizing hormone, estradiol, progesterone, anti-Müllerian hormone, and prolactin). These are all FDA-approved assays measured on Roche cobas® e801, assay parameters remained unchanged. Professional and self-collected capillary serum samples were acquired in parallel with the standard venous serum samples, to compare clinical equivalency of the capillary sampling option. In addition to isothermal stability studies at room temperature (20-25°C) and refrigerated (2-8°C) conditions, shipping excursion studies based on ISTA 7D recommendations were performed using a novel packaging solution to control sample temperature and thus, specimen integrity. Studies to assess matrix equivalency, linearity, and imprecision of this alternate sample type were also performed to demonstrate analytical performance. Results Method comparison of venous and professional collection of capillary samples demonstrated correlations (R) ≥ 0.9720 with slopes ranging from 0.919 to 0.971 and mean biases within ±8.2% for all analytes (n = 19-79). Self-collected capillary serum samples demonstrated correlations (R) ≥ 0.9827 with slopes that ranged from 0.841 to 0.985 and mean biases within ±10.7% (n = 16-26). Isothermal stability was demonstrated for each analyte up to 7 days at room temperature and refrigerated conditions. Simulated shipping excursion results were found to be acceptable for both winter and summer conditions with mean biases for each analyte within ±10.2% and ±19.2%, respectively. Matrix equivalency, linearity, and imprecision results adhered to current CLIA acceptance limits for each respective measurement. Conclusions The analytical and stability results affirm the feasibility of collecting capillary serum in a patient-centric manner, providing women with relevant information about their reproductive health.

Muscle strength as a marker of metabolic health in kidney transplant recipients: A cross-sectional study

BackgroundMuscle strength is often used as an indirect indicator of metabolic health across different age groups in healthy individuals. However, in kidney transplant recipients, this measure may be less accurate due to metabolic changes induced by immunosuppressive medications. AimTo compare muscle strength between kidney transplant recipients with metabolic syndrome (MS) and those without this condition. MethodsA cross-sectional analytical study was conducted with 29 participants (22 men and seven women) aged 18–50 years, having undergone a kidney transplant for over a year and without experiencing graft failure. To determine the presence of MS, the criteria proposed by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP-III) was used. Biochemical markers (triglyceride, total cholesterol, HDL, LDL, and glucose levels) were evaluated through a capillary sample. Muscle strength was assessed through three tests: long jump, elbow flexion, and grip strength. ResultsThe mean age was 36 ± 11.3 years, and the average transplant time was 4.5 ± 2.8 years. The prevalence of MS was 58.6%. Transplant recipients with MS performed less in all tests assessing muscle strength than those without this condition (p < 0.001∗). ConclusionsThe main finding of this research is that kidney transplant patients with MS performed worse in muscle strength tests compared to those without the condition.

General population screening for type 1 diabetes using islet autoantibodies at the preschool vaccination visit: a proof-of-concept study (the T1Early study)

ObjectiveType 1 diabetes (T1D) screening programmes testing islet autoantibodies (IAbs) in childhood can reduce life-threatening diabetic ketoacidosis. General population screening is required to detect the majority of children with T1D,...

Metabolic Phenotyping from Whole-Blood Responses to a Standardized Exercise Test May Discriminate for Physiological, Performance, and Illness Outcomes: A Pilot Study in Highly-Trained Cross-Country Skiers

BackgroundThis study used metabolic phenotyping to explore the responses of highly-trained cross-country skiers to a standardized exercise test, which was part of the athletes’ routine testing, and determine whether metabolic phenotyping could discriminate specific physiological, performance, and illness characteristics.MethodsTwenty-three highly-trained cross-country skiers (10 women and 13 men) participated in this study. Capillary whole-blood samples were collected before (at rest) and 2.5 min after (post-exercise) a roller-ski treadmill test consisting of 5–6 × 4-min submaximal stages followed by a self-paced time trial (~ 3 min) and analyzed using mass spectrometry. Performance level was defined by International Ski Federation distance and sprint rankings. Illness data were collected prospectively for 33 weeks using the Oslo Sports Trauma Research Center Questionnaire on Health Problems. Orthogonal partial least squares-discriminant analyses (OPLS-DA) followed by enrichment analyses were used to identify metabolic phenotypes of athlete groups with specific physiological, performance, and illness characteristics.ResultsBlood metabolite phenotypes were significantly different after the standardized exercise test compared to rest for metabolites involved in energy, purine, and nucleotide metabolism (all OPLS-DA p < 0.001). Acute changes in the metabolic phenotype from rest to post-exercise could discriminate athletes with: (1) higher vs. lower peak blood lactate concentrations; (2) superior vs. inferior performance levels in sprint skiing, and (3) ≥ 2 vs. ≤ 1 self-reported illness episodes in the 33-week study period (all p < 0.05). The most important metabolites contributing to the distinction of groups according to (1) post-exercise blood lactate concentrations, (2) sprint performance, and (3) illness frequency were: (1) inosine, hypoxanthine, and deoxycholic acid, (2) sorbitol, adenosine monophosphate, and 2-hydroxyleuroylcarnitine, and (3) glucose-6-phosphate, squalene, and deoxycholic acid, respectively.ConclusionMetabolic phenotyping discriminated between athlete groups with higher vs. lower post-exercise blood lactate concentrations, superior vs. inferior sprint skiing performance, and more vs. less self-reported illnesses. While the biological relevance of the identified biomarkers requires validation in future research, metabolic phenotyping shows promise as a tool for routine monitoring of highly-trained endurance athletes.

Looping Flexible Fluoropolymer Microcapillary Film Extends Analysis Times for Vertical Microfluidic Blood Testing.

The microfluidic measurement of capillary flow can be used to evaluate the response of biological samples to stimulation, where distance and velocity are altered. Melt-extruded multi-bored microfluidic capillaries allow for high-throughput testing with low device cost, but simple devices may limit control over sample flow when compared to the more complex "lab-on-a-chip" devices produced using advanced microfluidic fabrication methods. Previously, we measured the dynamics of global haemostasis stimulated by thrombin by dipping straight vertical microcapillaries into blood, but only the most rapid response could be monitored, as flow slowed significantly within 30 s. Here, we show an innovative method to extend both the stimulation process and flow measurement time without increasing the cost of the device by adding simple loops to the flexible extruded device. The loops enable longer time-scale measurements by increasing resistance to flow, thereby reducing the dependence on high stimulus concentrations for rapid reactions. The instantaneous velocity and equilibrium heights of straight and looped vertical microcapillary films were assessed with water, plasma and whole blood, showing that the loops create additional frictional resistances, reduce flow velocity and prolong residence times for increased time scales of the stimulation process. A modified pressure balance model was used to capture flow dynamics with the added loop. Looped devices loaded with thrombin and collagen showed an improved detection of blood stimulation responses even with lower stimulus concentrations, compared to straight vertical capillaries. Thrombin-activated blood samples in straight capillaries provided a maximum measurement zone of only 4 mm, while the looped design significantly increased this to 11 mm for much longer time scale measurements. Our results suggest that extending stimulation times can be achieved without complex microfluidic fabrication methods, potentially improving concentration-response blood stimulation assays, and may enhance the accuracy and reliability. We conclude adding a loop to low-cost extruded microfluidic devices may bring microfluidic devices closer to delivering on their promise of widespread, decentralized low-cost evaluation of blood response to stimulation in both research and clinical settings.

A comparative study between point‐of‐care hemoglobin (capillary samples) and laboratory hemoglobin result (venous samples)

AbstractObjectivePoint‐of‐care tests (POCTs) are commonly utilized in emergency departments. The purpose of this study was to evaluate accuracy and clinical utility of capillary POCT Hemocue (POCT Hcue) in emergency department setting.MethodsThis was a retrospective study. Accident and emergency department attendances ≥18 years old with a capillary POCT Hcue result and a paired venous hemoglobin (Hb) result were eligible. Statistical analyses including Pearson coefficient and Bland–Altman plot were performed to assess the relationship and agreement between capillary POCT Hcue and venous Hb.ResultsOne hundred and seven patients were included in the analysis. 59% were female. 67% of the patients were from triage category 3. Scatter plot revealed a linear relationship between capillary POCT Hcue and venous Hb, with a correlation coefficient calculated to be 0.95. The mean difference was −0.30 on the Bland–Altman plot with the limits of agreement from −1.83 to +1.22.ConclusionCapillary POCT Hcue had acceptable agreement with venous Hb in emergency department setting.

Beyond Glucose Monitoring: Multianalyte Sensor Use in Diabetes.

The incidence, prevalence, mortality, and health expenditure associated with diabetes continue to grow, despite efforts. The use of multianalyte sensors, which detect glucose as well as key analytes such as ketones, lactate, insulin, uric acid, and electrolytes, may provide additional information to guide earlier identification and management of diabetes and its complications. We undertook a narrative review using a systematic approach in May 2023, with a bridge search undertaken in April 2024. Four biomedical databases were searched: MEDLINE (Ovid), Embase, Emcare, and Cochrane Library. Searches for gray literature were conducted on ClinicalTrials.gov, Google Scholar, and websites of relevant organizations. Included studies incorporated articles on multianalyte sensors in diabetes and single-analyte sensors proposing integration into multianalyte diabetes management, with no limits placed on publication date and study design. Data were screened and extracted using CovidenceTM software. Overall, 11 articles were included, of which 7 involved multianalyte sensors (involving glucose and other analytes) and 4 single-analyte sensors (measuring non-glucose substances for proposed future integration into multianalyte systems). Analytes examined were ketones (n = 3), lactate (n = 4), uric acid (n = 3), insulin (n = 1), and potassium (n = 1). Results demonstrated that in vitro and invivo measurements of multi- and single-analyte sensors accurately and reliably corresponded with human capillary and serum samples. While the literature on this topic is sparse, our review demonstrated that measurement of glucose and other analytes can be feasibly undertaken using multi- and single-analyte sensors. More studies in humans are needed to establish clinical utility in diabetes self-management and assist with technological improvements.

Proof-of-concept study: Remote capillary blood collection for hCG analysis in early pregnancy

IntroductionCapillary blood collection, a technique traditionally used in diabetes care, shows promise for many applications including pregnancy monitoring. Serial measurement of serum human Chorionic Gonadotrophin (hCG) is frequently necessary for managing early pregnancy, including molar pregnancy, requiring multiple visits to a maternity hospital for blood collection by venepuncture. This proof-of-concept study aimed to assess the clinical performance and user acceptability of capillary blood samples collected remotely, as an alternative to venous blood for hCG measurement. MethodsWomen attending the early pregnancy unit who required serum hCG measurement, were invited to participate. Following informed written consent, participants were shown how to collect capillary blood samples using the Mini-Collect® collection device. Matched venous and capillary blood samples were collected in clinic for hCG comparison purposes. Participants were also supplied with a home collection kit in a prepaid return envelope. They were asked to perform a finger-prick blood collection at home using the instructions provided and to return the capillary blood sample by post within 24 h of collection, along with a completed user-satisfaction questionnaire. Statistical analysis was performed using Analyse-it® software. ResultsThe study enrolled 71 participants and over a third of these women collected a capillary blood sample at home. The median age of participants was 33 years (range 29–36). Passing-Bablok linear regression (y = -0.037 + 1.04x) and Spearman correlation (r = 0.999, p < 0.0001), demonstrated good agreement and strong correlation between venous and capillary samples, over a broad range of hCG values (1.2 to 224,0000 IU/L). The majority of capillary samples collected remotely (39%, 27/69) had sufficient blood volume for analysis (74%, 20/27). Respondents (77%, 18/25) found the collection device easy to use and expressed willingness to use a future service if available (80%, 20/25) ConclusionThe study demonstrated excellent agreement between the hCG results obtained from both collection methods, suggesting that capillary blood can serve as a reliable alternative for venous hCG measurement, particularly in clinical settings requiring frequent hCG monitoring. Feedback from the study questionnaire indicates a preference for this type of follow-up among women, indicating potential improvements in compliance for blood based diagnostic tests.

Feasibility, reliability and satisfaction of (automated) capillary carcinoembryonic antigen measurements for future home-based blood sampling: the prospective CASA-I study.

Follow-up for colorectal cancer (CRC) necessitates regular monitoring of carcinoembryonic antigen (CEA) at the hospital. Capillary home-based blood collection, including minimally invasive techniques such as lancet sampling or an automated upper arm device (TAP-II), has the potential to replace a significant portion of hospital-based blood sampling, thereby enhancing self-reliance and quality of life. The objectives of this study were to assess the feasibility, reliability and preference for CEA blood collection. Baseline venous and capillary (by lancet and TAP-II) blood samples were collected from 102 participants, including 20 CRC patients with elevated CEA levels, 60 CRC patients undergoing postoperative outpatient monitoring and 20 healthy volunteers. The second group performed capillary blood collections at home on two consecutive follow-up appointments and subsequently sent them to the hospital. Satisfaction was assessed via patient reported outcome measures on pain, burden, ease of use and preference. The Pearson's correlation test of all usable samples resulted in a linear coefficient of 0.998 (95% CI 0.997-0.998) for the TAP-II method and 0.997 (95% CI 0.996-0.998) for the lancet method, both compared to venipuncture. Following the initial blood collection, 86% of the participants (n = 102) favoured the TAP-II, rating it as the least painful and burdensome option. After two home-based blood samples, the preference for the TAP-II method persisted, with 64% of the patients endorsing its use. This study demonstrated the feasibility of home-based capillary sampling of CEA. The TAP-II blood collection is the most reliable method and is preferred by patients over venipuncture and lancet sampling.

Capillary versus Venous Glucose for the Screening 1-Hour Glucose Tolerance Test for Gestational and Pregestational Diabetes

Purpose: This study aimed to assess for disparities between capillary blood glucose and plasma glucose for the O’Sullivan 1-hour glucose tests. Methodology: Subjects included were English-speaking, non-incarcerated, adult (&gt;18 years old) pregnant patients who could give informed consent. Patients were approached at their outpatient obstetric office visits. After receiving written and verbal consent, patients were given a 50-g glucose load at the conclusion of their clinic visit. Strictly timed venous and capillary blood draws were performed at the outpatient labs. The venous and capillary blood samples were drawn within less than 5 minutes of each other and analyzed using select chemistry analyzers within less than one hour. Quality control measures, including recalibration, testing, and various quality control mechanisms, were reassessed every 24 hours. Data was tested for normal distribution with the Shapiro-Wilk test and Kolmogorov-Smirnov tests. Paired T-tests were used to compare the average difference between measurements in subjects on GraphPad. Results: One hundred patients had enrolled in the study, with ten dropping out soon after being consented. Patients were lost due to nausea and vomiting with the 50-gram glucose load (4 patients) and scheduling conflicts (6 patients). Demographics identified 84% as African American (76/90), average body mass index (BMI) being 35.4 kg/m2, and a mean age of 26. All data of the differences (capillary minus venous glucose) were found to be normally distributed. The capillary sample was significantly different from the venous sample, with the former being, on average 6.156 mg/dL higher than the latter (P 0.0008, CI 2.65 to 9.66). Subgroup analysis suggested significant differences in values among the multiparous patients (P 0.0014, CI -13.18 to -3.349), with capillary glucose being on average 8.26mg/dL higher. Similarly, patients with BMI &lt; 30 mg/kg had significantly different sample values (P 0.0031, CI -18.75 to -4.25), with capillary glucose being 11.50 mg/dL higher on average. Patients with a gestational age of 24 weeks and beyond also had significantly different samples based on collection site (P 0.0023, CI 2.7 to 11.75), with capillary being on average 7.226 mg/dL higher. Patients with BMI 30.0 to 39.9 had no significant difference between capillary and venous glucose (P 0.2393, CI -8.72 to 2.25), with capillary being 3.24 mg/dL higher on average. Patients with BMI 40 or higher also showed no significant difference between venous and capillary glucose (P 0.1053, CI -10.11 to 1.030), with capillary glucose being on average 4.52 mg/dL higher. Nineteen (21%) patients failed their glucose test based on one or both samples. In 12 patients (13%), the two samples were in agreement for test failure. However, seven patients (7.8%) had discordant results where the glucose was less than 140 mg/dL for one sample and higher for the other. Furthermore, 4 of these patients passed by the venous sample and failed with the capillary, and the reverse in sample source occurred in 3 patients. None of the patients with discordant results failed their 3-hour confirmatory test. Discussion: All pregnant patients undergo gestational diabetes mellitus (GDM) screening, and those with diabetes risk factors such as obesity and a history of GDM undergo early diabetes screening. The two-step approach commonly used in the United States is a one-hour 50-gram oral glucose tolerance test (OGTT) using a venous plasma glucose sample. If a patient fails (glucose &gt; 140 mg/dL), she undergoes a 3-hour OGTT. Other accepted cutoffs for the one-hour OGTT are 135 mg/dL and 130 mg/dL. Venous sampling has some factors which lead to inaccuracy, including ongoing glycolysis in samples and decreased concentration compared to capillary/arterial samples in postprandial patients. Capillary sampling can be inaccurate in patients with microvascular disease such as shock, COPD, and Raynaud’s disease. Our institution uses point-of-care testing (POCT) on capillary (finger-stick) using a glucometer with a 140 mg/dL cutoff. Studies are mixed in their endorsement of POCT for the diagnosis/screening of DM. This study suggests that capillary testing is more sensitive to hyperglycemia in postprandial patients and is more sensitive for non-obese, multiparous, and patients undergoing screening for gestational diabetes at 24 weeks GA and beyond. This study also suggests that if POCT/capillary testing is considered, the higher (140) cutoff may be the best. The findings do not show that there is a significant risk of missing diagnoses of GDM, but a higher incidence of needing 3-hour glucose tolerance testing due to its higher sensitivity.

Inflammatory markers in relation to maternal lifestyle and adverse pregnancy outcomes in twin pregnancies

It is well known that inflammatory markers play an important role in the development and maintenance of healthy pregnancies. However, the literature regarding inflammation in relation to lifestyle and adverse pregnancy outcomes in twin pregnancies is remarkably uncovered. Therefore, this study aimed at evaluating the concentration of inflammatory markers in dried capillary blood spot samples from 523 women with twin pregnancies, included at a median gestational age of 21+1 weeks. The relationship between inflammatory markers and maternal lifestyle (current smoking status and pre-pregnancy body mass index) in addition to adverse pregnancy outcomes (preeclampsia, gestational diabetes mellitus, and small for gestational age) was analyzed. The study showed that active smoking at inclusion was associated with an elevated concentration of interleukin-8. Furthermore, maternal obesity was associated with an elevated concentration of C-reactive protein and monocyte chemoattractant protein-1. Analysis of the data showed no statistically significant variations in the concentration of the assessed inflammatory markers for neither preeclampsia, gestational diabetes mellitus, nor small for gestational age. The current study promotes future research on the pathophysiology of twin pregnancies in relation to adverse pregnancy outcomes, as the literature within the area remains scarce.