Reference Range Research Articles

B-085 Optimizing Thyroglobulin Antibody Interference Thresholds to Minimize Turn-around Time

Abstract Background Serum thyroglobulin (Tg) is a key biomarker used to detect disease recurrence in patients with differentiated thyroid cancers who have undergone complete thyroidectomy. Thyroglobulin antibodies (TgAb) can interfere with accurate measurement of serum Tg levels, producing falsely low results in automated immunoassays. Thus before measurement of Tg, TgAb levels are measured to determine if in-house immunoassays can be used or if the patient’s sample will need to be sent out for radioimmunoassay (RIA) or mass spectrometry methodologies, which are less sensitive to TgAb interference. We recently transitioned to new instrumentation and noted a sharp increase in Tg samples with TgAb interference that needed to be sent out when we used the limit of detection (LOD) of the Roche TgAb assay. This increases turnaround times for patients and increases laboratory costs. We hypothesized that the LOD of the Roche TgAb assay is below the level of interference in Tg immunoassays. To test this we compared the performance of TgAb immunoassays (IA) and Tg measurements by IA and RIA with the intention of proposing a more appropriate threshold for TgAb interference for the Roche TgAb assay. Methods We collected 121 serum specimens, which were above the LOD of the Roche TgAb (R-TgAb) assay, which is 10 IU/mL. These specimens were sent as part of standard care to USC for measurement of TgAb by Kronus (K-TgAb) and Tg by RIA. On these split samples we also measured Tg by Beckman Access (B-Tg). We compared the detection of TgAb by USC to varying thresholds of Roche TgAb measurements (10 IU/mL [LOD], 20 IU/mL, and 115 IU/mL [reference interval for autoimmunity]), and assessed the agreement between Tg measurements by Beckman IA and USC RIA for different Roche TgAb thresholds. Analyses were performed in Prism Graphpad using linear regression. Results Qualitatively, the concordance for R-TgAb to RIA (reference) at 10 IU/mL was 31%, at 20 IU/mL was 90%, and at 115 IU/mL was 80%. Quantitative agreement between the B-Tg immunoassay and RIA for the TgAb thresholds of: TgAb >10 IU/mL gave an R2=0.97 for Tg comparison, >20 IU/mL gave an R2=0.99, and >115 IU/mL R2=0.99. Conclusions Prior studies have shown that TgAb immunoassays can produce significant qualitative and quantitative differences. In our study, we attempt to validate the use of the Roche immunoassay with a cutoff of 20 IU/mL to minimize interference between Tg and TgAb in order to accurately detect recurrence of thyroid cancer. We found that a TgAb cutoff of 20 IU/mL we maintained acceptable agreement between Tg methods indicating no significant interference up to 20 IU/mL. With the TgAb cutoff of 20 IU/mL, we would be able to reduce sendouts for this cohort from 121 to 42, reducing sendouts by 65% and allowing a faster turnaround time for a significant proportion of our patients.

A-164 Establishment and Verification of Reference Intervals for Red Blood Cell Series and Total Leukocytes in Whole Blood Counts of Chilean Adults Using refineR and Multi Criteria Expectation Maximization Methods

Abstract Background This study aimed to define RIs for red blood cell series and total leukocytes in the complete blood count, in adult patients. Methods We used a sample of 822 patients aged 18 to 60 years, both female and male. The study focused on the red blood cell series (RBC Count, hemoglobin, Hematocrit, MCV, MCH, MCHC and RDW) and total leukocytes. RIs and respective 90% confidence intervals were estimated using the refineR method and a multi-criteria method combining the Expectation Maximization algorithm, mode, antimode analysis, an adapted Horn algorithm (5 cycles of Tukey's test with intermediate trimming and 2 cycles of Tukey's test with Box-Cox transformed data if applicable after analyzing Lambda, kurtosis, and skewness coefficients) and distribution truncation based on clusters and antimode. The RIs estimates using refineR and multi-criteria methods were compared to the manufacturer's specifications (Mindray). Flagging Rates were used to validate the method that estimates the most representative RI for the population served by the laboratory. Equivalence Interval and Bias Ratio were utilized to assess the practical relevance of sex-based partitioning. Results The method based on the multicriteria approach demonstrated the best performance, with flagging rates showing results lower than 4.7% and higher than 0.9% after the truncation of the results distribution. In general, the refineR method generated very narrow RIs, while the manufacturer's specifications resulted in very wide or shifted RIs, which do not adequately represent the data distribution profile. It was identified the need to partition by sex for the parameters Red Blood Cell Count, Hemoglobin, and Hematocrit, which is in agreement with the manufacturer's specifications. Conclusions The estimated RIs better represent the laboratory-served population, highlighting the importance of adhering to ISO 15189 normative requirements. This involves verifying and/or determining RIs to provide representative information of the served population, thereby aiding in medical decision-making.

Multidisciplinary approach to redefining thyroid hormone reference intervals with big data analysis

ObjectivesThis study aimed to employ big data analysis to harmonize reference intervals (RI) for thyroid function tests, with refinement to the TSH upper reference limit, and to optimize the TSH reflex algorithm to improve clinical management and test utilization. Design & methodsTSH, free T4, and free T3 results tested in Alberta, Canada, on Roche Cobas and Siemens Atellica were extracted from the laboratory information system (N = 1,144,155 for TSH, N = 183,354 for free T4 and N = 92,632 for free T3). Results from specialists, inpatients, or repeat testing, as well as from positive thyroid disease, autoimmune disease, and pregnancy biomarkers were excluded. RIs were derived using statistical models (Bhattacharya, refineR, and simple non-parametric) followed by endocrinology and laboratory review. ResultsThe TSH RIs for 0 to 7 days, 8 days to 1 year, and ≥1 year were 1.23 to 25.0 mIU/L, 1.00 to 6.80 mIU/L and 0.20 to 6.50 mIU/L, respectively. The free T4 RIs for 0 to 14 days, 15 to 29 days, and ≥30 days were 13.5 to 50.0 pmol/L, 8.7 to 32.5 pmol/L, and 10.0 to 25.0 pmol/L, respectively. An updated TSH reflex algorithm was developed based on the optimized TSH and free T4 RIs, with free T4 reflexed only at a TSH of <0.1 mIU/L. ConclusionsThe collaboration of a multidisciplinary team and the utilization of big data analysis led to the enhancement of thyroid function RIs, specifically resulting in the widening of the upper TSH reference limit to 6.50. Application of these optimized RIs with the TSH reflex algorithm will serve as a guide for improvement in interpretation of thyroid function tests.

Confusion in the interpretation of prolactin levels caused by inappropriately low reference intervals.

Serum prolactin measurements are important in the differential diagnosis of pituitary masses and subfertility. We observed discrepancies in serum prolactin levels in several patients measured with different immunoassays. Despite differences in assay results, the reference intervals derived by the manufacturers were similar. In this study we aimed to investigate prolactin assay differences and to re-establish RIs for different prolactin immunoassays. For the assay comparison, serum samples were collected from men and women visiting our the Amsterdam UMC hospital. Prolactin levels were measured using the AtellicaTM IM analyzer (Siemens Healthineers) and the Cobas (Roche Diagnostics) immunoassay. Reference intervals for prolactin were re-established for men, premenopausal women and postmenopausal women for both the Atellica and Cobas immunoassay. Prolactin levels measured using the Cobas immunoassay were 1.75 times higher than those measured using the Atellica immunoassay. The re-established reference intervals for Atellica and Cobas confirmed these findings and were <0.32 U/L; <0.55 U/L for men; <0.64 U/L; <0.86 U/L for premenopausal women and <0.31 U/L; <0.59 U/L for postmenopausal women, respectively for Atellica and Cobas assays. The re-established RIs of the Atellica assay matched the current and manufacturer RIs whereas those for Cobas differed substantially. Prolactin levels are assay dependent and the re-established reference intervals are different for the Atellica and Cobas assays. We recommend that laboratory specialists and manufacturers periodically review prolactin assay RIs as incorrect reference intervals can lead to misinterpretation of prolactin levels and unnecessary referrals and further laboratory testing, as we have experienced.

Calculation of continuous reference intervals for biological parameters exhibiting strong age-dependent level changes: Its application to glycosaminoglycans and sialic acid in urine.

Glycosaminoglycan (GAG) and sialic acid (total and free) assays are used as first-line screening tests for the diagnosis of mucopolysaccharidoses and glycoproteinoses, respectively. There is a pronounced age-dependent variation in the urinary concentrations of these metabolites in the normal population, and the stratification of the reference values into discrete age ranges may lead to an undesirably high number of false-positive or false-negative results. The aim of this study was to design a method for calculating continuous reference intervals as a function of age and its application to the analysis of GAGs and sialic acid (total, free, and conjugated) in urine. In the postpubertal period, concentrations of urinary GAGs and sialic acid have reached a plateau, so a traditional calculation of the reference range in this specific age group was considered appropriate. In the prepubertal period, a nonlinear regression performed with the Excel add-in Solver was used to fit the logarithmized concentrations of the controls to a curve that represents the mean values as a function of age. A uniform distribution of the residuals was obtained, which allowed the calculation of the reference intervals by adding the values of their 2.5 and 97.5 percentiles to the independent variable of the regression curve to calculate the upper and lower reference curves. The main advantages of the developed method are (1) a reduction in the number of control samples needed to obtain adequate reference intervals and (2) an improvement in the reliability of diagnostic screening by reducing the uncertainty generated by the gaps in the traditional age-stratified method.

Electrocardiographic abnormalities are frequently detected in healthy adult Borzoi with a normal echocardiogram.

Borzoi reportedly experience sudden death. The objective of this study was to report ECG intervals, amplitudes, and frequency of ECG abnormalities in clinically healthy Borzoi. 98 clinically healthy Borzoi were prospectively recruited and underwent echocardiogram, ECG, and cardiac troponin I testing between October 2020 and December 2022. Standard ECG measurements were obtained. Early repolarization notches and slurs were recorded. Of 82 Borzoi with a structurally normal echocardiogram, ventricular arrhythmias were documented in 8 (10%) dogs, all of which had normal cardiac troponin I concentrations. Median P wave duration was 55 milliseconds (range, 45 to 70 milliseconds). Median PR interval was 125 milliseconds (range, 80 to 175 milliseconds). Thirty-one (38%) Borzoi had first-degree atrioventricular block (PR interval > 130 milliseconds). Median QRS duration was 65 milliseconds (range, 48 to 90 milliseconds). Median QT interval was 235 milliseconds (range, 185 to 275 milliseconds). Twenty-nine (35%) and 15 (18%) of 82 Borzoi had QT intervals > 240 or > 250 milliseconds, respectively. Sixty-seven of 82 (82%) Borzoi had early repolarization notches or slurs. Seventeen of 82 (21%) Borzoi had an abnormality of the ST segment, most commonly convexity/doming. Convexity of the ST segment was intermittent (n = 9) or persistent (4). Ventricular arrhythmias, early repolarization, prolonged QT intervals, and ST segment abnormalities are not infrequent in clinically healthy Borzoi. P, PR, and QRS durations are commonly prolonged compared to general canine reference intervals. Future study into heritable channelopathies in Borzoi is warranted given the frequency of ventricular arrhythmias, repolarization abnormalities, and sudden death in the breed. Breed-specific ECG reference intervals are needed.

Glomerular filtration rate determined by measuring serum clearance of iohexol in unanesthetized cheetahs (Acinonyx jubatus) with comparison to serum symmetric dimethylarginine.

One of the more common diseases affecting zoo-managed cheetahs (Acinonyx jubatus) is chronic renal disease, which can impact their welfare and ultimately shortens their lifespan. Early diagnosis, for which estimating Glomerular Filtration Rate (GFR) is one such tool, is imperative to help mitigate the negative impacts of this insidious disease. GFR was determined by measuring the serum clearance of iohexol in nine clinically normal, cheetahs managed under human care that presented for voluntary blood collection. A 2-sample iohexol clearance method was performed, along with serum symmetric dimethylarginine (SDMA) determination. SDMA has shown promise in humans, dogs, and cats, as an early biomarker of renal disease. Additionally, the relationship between GFR and SDMA, along with serum creatinine and BUN were analyzed. The mean values for the uncorrected GFR and corrected GFR were 2.08 ± 0.215 mL/min/kg body weight and 1.87 ± 0.173 mL/min/kg body weight, respectively. No significant correlations were observed between GFR, SDMA, serum creatinine, or BUN. Both the uncorrected and corrected iohexol-based GFR values were similar to an inulin-based GFR reference interval determined in zoo managed cheetahs and a reported domestic cat iohexol-based GFR reference interval. Serum SDMA values support previous research suggesting cheetahs have a separate reference interval from domestic cats (0-14 μg/dL). Measuring GFR by the serum clearance of iohexol shows promise as a readily available, cheap, and easily administered clearance marker that can be used in cheetahs trained for voluntary blood collection, thereby avoiding the need for anesthesia.

Thyroid function tests in healthy kittens aged between 2 and 16 weeks.

This study aimed to determine thyroid hormone concentrations in a cohort of healthy kittens due to the paucity of information in the literature, and the potential for congenital hypothyroidism (CH) to contribute to fading kitten syndrome (FKS). The serum concentrations of total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), free triiodothyronine (fT3) and thyroid-stimulating hormone (TSH) were measured in 19 healthy kittens aged 2-16 weeks. Mean TT4, fT4, TT3 and fT3 concentrations significantly differed across age groups. Mean TT4 and fT4 concentrations peaked at 6 and 5 weeks of age, respectively. The TT4 concentration exceeded the adult cat reference interval (ACRI) in 54% (32/59) of samples at week 6, with the highest TT4 concentration being 7.1 µg/dl (91 nmol/l). Mean TT3 and fT3 concentrations also peaked at 6 weeks of age. Mean TT3 concentration started below the ACRI until 4 weeks of age, after which it remained within the ACRI. The mean fT3 concentration was within the ACRI at all ages. The mean TSH concentration did not differ across age groups and remained within the ACRI in nearly 100% of samples. Peak TT4, fT4, TT3 and fT3 concentrations in healthy kittens at 5 and 6 weeks of age are likely due to changes in the maternal transfer of thyroid hormones after weaning and organ system development. Knowing healthy neonatal and pediatric thyroid hormone concentrations in a cohort of kittens might help a veterinarian interpret thyroid hormone levels when trying to rule out CH in a kitten with FKS.

Rapid Access Diagnostics for Asthma (RADicA): protocol for a prospective cohort study to determine the optimum series of investigations to diagnose asthma using conventional and novel tests

IntroductionThe diagnosis of asthma is often based on characteristic patterns of symptoms in the absence of an alternative explanation, resulting in over and under diagnosis. Therefore, diagnostic guidelines usually recommend...

Method validation of an inductively coupled plasma mass spectrometry (ICP-MS) assay for the analysis of magnesium, copper and zinc in red blood cells

BackgroundLaboratory measurements of trace elements such as magnesium (Mg), copper (Cu), and zinc (Zn) in red blood cells (RBCs) are essential for assessing nutritional status and diagnosing metal toxicity. The purpose of this study was to develop and validate an ICP-MS method for quantifying these elements in RBCs. MethodsPacked RBCs were aliquoted and diluted in an alkaline diluent solution containing internal standards, 0.1 % Triton X-100, 0.1 % EDTA, and 1 % ammonium hydroxide. The resulting diluted specimen was analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to quantitatively determine the levels of Mg, Cu, and Zn. The method underwent validation for accuracy, precision, method comparison, linearity, analytical sensitivity, and carryover. Additionally, retrospective data were analyzed, and non-parametric reference intervals were calculated. ResultsAccuracy and linearity fell within the expected range of ≤±15 % for all analytes. Within-run, between-run, and total imprecision were ≤15 % coefficient of variation. All other validation experiments met the established acceptance criteria. Retrospective data analysis was conducted on patient samples using the method. The application of Tukey’s HSD test for multiple comparisons revealed statistically significant mean differences (p < 0.05) in Mg, Cu, and Zn concentrations between all pairwise groups of age and sex, except for the mean Cu concentration in adult males versus females and the mean Mg concentrations in adult versus minor males. ConclusionsThe presented method was successfully validated and met the criteria for clinical use. Retrospective data analysis of patient results demonstrated the method’s suitability for assessing nutritional deficiency and toxicity.

Coagulation profiles and percentiles in neonates with hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia: A step toward more accurate transfusion thresholds.

In the literature, there are no studies about the transfusion threshold for neonates with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). In order to facilitate accurate interpretation of coagulation results in these neonates, we aimed to generate specific reference intervals in this specific population. This retrospective study included all HIE neonates admitted from 2014 to 2022 to undergo TH. All infants during TH underwent blood exams, including the coagulation profile. Our primary outcome was to assess the estimates of the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles for each parameter on admission (before transfusion). By the receiver operating characteristic (ROC) analysis, the area under the ROC curve (AUC) and the best cut-off point were used to evaluate the ability of the prothrombin time expressed as international normalized ratio (PT-INR) to predict the risk of any bleeding. A total of 143 infants were included in this study. On admission, the median fibrinogen value was 205mg/dL, prothrombin time 18.6seconds, PT-INR 1.50, activated partial thromboplastin time 38.3seconds, thrombin time 18.6seconds, antithrombin 57.0%. The optimal cut-off of PT-INR in predicting the risk of any bleeding was greater than 1.84 (AUC.623, p=.024). For the first time, we proposed the percentiles of coagulation parameters in our cohort of neonates with HIE. Furthermore, we found that a PT-INR greater than 1.84 can significantly predict the risk of any bleeding. Further studies are needed to determine if a restrictive versus a liberal transfusion approach can be equally safer for these high-risk infants.

Efficacy of ultrasonographic diaphragmatic parameters in distinguishing diaphragmatic dysfunction in cats.

Diaphragmatic dysfunction (DD) is often underdiagnosed in veterinary medicine. Various ultrasonographic diaphragmatic parameters, including diaphragmatic excursion (DE), diaphragmatic thickness (Tdi) and diaphragmatic thickening fraction (DTF), can be used to identify DD. We aimed to establish normal reference intervals in healthy cats, examine the effects of intrinsic factors on diaphragmatic parameters and evaluate the efficacy of these parameters in identifying DD in healthy and diseased cats. This prospective observational study was conducted on 22 healthy cats and 12 diseased cats using ultrasonographic techniques to evaluate DE, Tdi and DTF. The correlation between diaphragmatic parameters and intrinsic factors, including sex, age, body weight and body condition score, was analysed using Pearson correlation analysis. Cut-off values for healthy and diseased cats were established using receiver operating characteristic curve analysis. The mean DEs of the left and right hemidiaphragms were 0.66 ± 0.16 and 0.64 ± 0.18 cm, respectively. The mean Tdis in the end-inspiration phase were 0.13 ± 0.03 and 0.12 ± 0.03 cm for the left and right hemidiaphragms, respectively, whereas in the end-expiration phase the mean Tdi was 0.07 ± 0.03 cm for both hemidiaphragms. The DTF ranges for the left and right hemidiaphragms were 23.90-122.1% and 38.80-107%, respectively. Intrinsic factors had no significant impact on DE, Tdi and DTF. The DE measurements for the left hemidiaphragm were more accurate for evaluating diaphragmatic function. To distinguish between healthy and diseased cats, the cut-off value, sensitivity and specificity were 0.458 cm (area under the curve [AUC] 0.846), 75.00% and 86.36%, respectively, for the left hemidiaphragm and 0.423 cm (AUC 0.704), 41.67% and 100%, respectively, for the right hemidiaphragm. Normal reference values for DE, Tdi and DTF were established for healthy cats. DE, particularly in the left hemidiaphragm, obtained using routine ultrasonography, improves the efficacy of identifying DD and assists clinicians in the diagnosis and treatment of cats with cardiorespiratory disease.

Derivation of Russian-specific reference intervals for complete blood count, iron markers and related vitamins.

This study aimed to establish reference intervals (RIs) for Russian adults for hematological parameters including related iron markers and vitamins. Sources of variation of reference values (RVs) and needs for secondary exclusion were explored for proper derivations of RIs. Following the harmonized protocol of the IFCC Committee on Reference Intervals and Decision Limits (C-RIDL), 506 healthy Russians (age 18-80; 46% male) were recruited. Complete blood counts (CBC) and leukocyte differentials, iron markers, vitamin B12, and folate were measured by Beckman Coulter's analyzers. Sources of variation were analyzed by multiple regression analysis, and ANOVAs, and the need for partitioning RVs was decided accordingly. Two schemes of excluding latent anemia were compared: (1) latent abnormal values exclusion method (LAVE) based on associations among CBC parameters, or (2) explicit exclusion of individuals with either ferritin or iron below the respective lower limit of the manufacturer. RIs were determined by the parametric method using two-parameter Box-Cox formula. Gender-specific RIs were required for most analytes, while age-specific RIs were set only for ferritin in females. A BMI-related increase in RVs was prominently observed for reticulocyte parameters, hence we chose to exclude individuals with BMI>28 kg/m2 when establishing the RIs. The LAVE method was more effective in excluding individuals with latent anemia, than exclusion based on low ferritin and/or iron values. International comparison revealed that Russian RIs featured a lower side shift of platelet counts. Similar to African countries, Russian RIs for total leukocyte and neutrophil counts were lower compared to most of other countries. RIs for the Russian population for 34 hematological and related parameters were established using up-to-date methods proposed by C-RIDL. Reducing the influences of latent anemia and obesity on RIs was crucial for erythrocyte parameters. Low levels of Russian RIs observed for platelet and neutrophil counts need further investigation.

Two-dimensional echocardiographic right heart ratios for assessment of right heart size in dogs: Reference intervals and reproducibility.

Reference intervals for simple body weight-independent measurements of right heart size and function are limited. Generate reference intervals for measurements of right heart size indexed to the long-axis aortic valve diameter (AoD) or corresponding left heart structure (right heart ratios) and describe the reproducibility of these indices. Ninety healthy adult dogs of variable body weight. Prospective study. All dogs underwent an echocardiogram performed by the same operator. Numerous linear 2-dimensional measurements of right heart size and function from different imaging planes were performed. Eight dogs underwent repeated echocardiograms by the same operator on 3 different days, and 3 different operators performed repeated echocardiograms on the same day. Reference intervals were generated using the Clinical Laboratory Standards Institute method. Reproducibility was quantitated using coefficients of variation (CVs) and reproducibility coefficients. Reference intervals for right heart ratios were generated and allow simple assessments of right heart size and function that do not require a scaling exponent or body weight table. Right heart ratios did not show clinically relevant associations with body weight. All CVs were <22.6%. In general, CVs for right heart measurements indexed to AoD were lower compared with right heart measurements indexed to the corresponding left heart structure. Reference intervals for simple body weight-independent right heart ratios are available to help detect abnormalities of right heart size and function. Reproducibility coefficients might be useful to help identify meaningful changes in right heart size during serial evaluations.

Establishment of reference intervals of haematology and biochemistry analytes in ICR mice of different ages.

Outbred stocks of mice are widely used in pre-clinical research as these animals possess a diversified genetic background when compared with inbred strains of mice. It is crucial to assess particular alterations in the physiological and functional profiles of laboratory animals using haematological and biochemical indicators. These values can also differ between laboratories because they are influenced by many different factors. We aimed to provide normal values and reference intervals for selected haematology and biochemistry analytes of 570 ICR mice at three different ages: 6-8 weeks, 10-14 weeks and 6-9 months. Reference values were calculated by non-parametric methods. For comparisons between sexes, the independent-sample t-test and Mann-Whitney test were employed, and analysis of variance was used for age differences. The findings of the study revealed age-related declines in haemoglobin concentration, haematocrit, mean corpuscular volume and mean corpuscular haemoglobin concentrations. Mice aged 6-9 months had statistically higher platelet counts in their blood than mice of other ages. The white blood cell count had a significant age effect and progressively decreased with age. As mice get older, the percentage of neutrophils, monocytes and basophils increases, but the percentage of lymphocytes decreases. For the biochemical values, age-related significant differences in glucose, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and albumin concentrations were found. It was also found that creatinine concentrations were comparable across all age ranges. The values presented in the present work can be used as a reference to interpret clinical pathology data for other studies and to evaluate health status.

Hair fragility (trichorrhexis nodosa) in alopecic Pomeranian dogs.

While alopecia associated with hair cycle arrest (HCA, Alopecia X) is well-recognised in Pomeranian dogs, the authors are unaware of reports of concurrent hair fragility. Following the observation of frequent hair shaft abnormalities in alopecic Pomeranians, we hypothesised that hair fragility events would be more frequent in dogs with a phenotype of HCA when compared to dogs with normal coats. Eight alopecic Pomeranian dogs or crosses with a phenotype of HCA and 36 unaffected Pomeranians with owner-reported normal hair coats. All affected dogs underwent dermatological examination and clinicopathological evaluations. Hair samples, plucked from affected areas or obtained by brushing from unaffected dogs, were examined microscopically for structural abnormalities. Hair fragility events were characterised as trichorrhexis nodosa (TN) or longitudinal splits and were expressed per 10 mg of hair. A reference interval was calculated from the number of hair fragility events in the samples from unaffected dogs. The upper reference limit (with 90% confidence) from samples of 35 unaffected Pomeranians (one outlier excluded) was 9.75 hair fragility events per 10 mg of hair. The median (range) of fragility events in eight dogs with a phenotype of HCA was 66.0 (30.2-166.7) per 10 mg of hair. Clinicians should routinely perform trichography in Pomeranians with HCA because abundant hair abnormalities, particularly TN, may contribute to poor hair coat quality. Further studies are required to establish the pathophysiology of and treatments for these fragility events and to determine their predictive value for HCA.

Reference Intervals for the ratio of Soluble FMS-like Tyrosine Kinase-1 and Placental Growth Factor in Pregnant and Non-Pregnant Females in Pakistani Population

Reference Intervals for the ratio of Soluble FMS-like Tyrosine Kinase-1 and Placental Growth Factor in Pregnant and Non-Pregnant Females in Pakistani Population

Impact of blood volume, air exposure duration, transport duration, and testing delay on plasma total carbon dioxide in simulated open collections using microtainers

BackgroundExposing blood specimens to air reduces plasma total carbon dioxide (TCO2). We evaluated the degree of TCO2 reduction attributed to open collection of neonatal blood in BD microtainers® (microtainers), microtainer transport duration and delayed testing of open plasma aliquots. MethodsVenous blood was aliquoted into open microtainers in a 3x4 factorial design to simulate combined effects of blood volume (0.2–0.6 mL) and air exposure duration (0–5 min), with blood drawn in vacutainers as a control. Separate effects of in-hospital transport duration (0–120 min; whole blood), off-site transport duration (0–24 h; centrifuged whole blood), and the duration plasma aliquots remained open (0–120 min) were evaluated by repeated testing. Findings were analyzed using repeated-measures ANOVA and Student’s T-tests. ResultsIn the factorial experiment, mean plasma TCO2 in microtainers was on average 3.5 mmol/L lower than in vacutainers. Smaller blood volume but not greater air exposure duration significantly (p < 0.05) reduced TCO2. Mean TCO2 in filled (0.6 mL; 1–5 min air exposure) microtainers was on average 2.9 mmol/L lower than in vacutainers. Simulated off-site transport of microtainers containing centrifuged whole blood significantly reduced TCO2 (4 h; mean change = -1.5 mmol/L), as did delayed testing of aliquoted plasma (15 min; mean change = -1.3 mmol/L). ConclusionsPlasma TCO2 decreased with reduced microtainer blood volume, extended off-site transport duration of centrifuged whole blood and testing delay of aliquoted plasma. To minimize TCO2 reduction, microtainers should be fully filled and tested rapidly. Laboratories should also consider whether an interpretive comment, correction factor or separate reference intervals are appropriate for these tests.

Cerebrospinal Fluid Homovanillic and 5-Hydroxyindoleacetic Acids in a Large Pediatric Population; Establishment of Reference Intervals and Impact of Disease and Medication.

Cerebrospinal fluid (CSF) homovanillic (HVA), and 5-hydroxyindoleacetic acids (5-HIAA) are biomarkers of neurological diseases affecting the dopaminergic and serotoninergic pathways. Establishing reference intervals for these metabolites faces the challenges of a lack of healthy controls and a negative correlation with age, making stratified intervals unrealistic. We propose a pipeline to determine continuous reference intervals for HVA and 5-HIAA using an indirect method. We also studied the confounding effects of different variables and explored the impact of antiepileptic and neuroleptic treatments on HVA and 5-HIAA values. The study used least squares regression to fit age-concentration curves from a cohort of pediatric patients (n = 1533), where the residuals represent metabolite values excluding age effect. Presuming that HVA and 5-HIAA primary deficiencies characterize a distinct subpopulation, we fitted a two-component finite mixture model in age-normalized data and set reference intervals at the central 95% of the nondeficient population. Patients with primary genetic deficiencies of HVA and/or 5-HIAA consistently fall outside the proposed continuous reference intervals. Using the new continuous reference intervals reduces the number of secondary deficiencies detected compared with using stratified values. No correlations were observed between CSF HVA and 5-HIAA values across the studied drug categories (antiseizure and neuroleptic medications). In addition, biopterin values positively influenced both metabolite concentrations. The proposed continuous reference intervals caused a substantial reduction in the number of secondary deficiencies detected, most of which demonstrated no conclusive correlations between the diseases and altered HVA and 5-HIAA values.

Preliminary evaluation of ionized magnesium levels in dogs on long-term esomeprazole administration.

To investigate the level of whole-blood ionized magnesium (iMg) in dogs with long-term use of proton pump inhibitors (PPIs). The study included 10 client-owned dogs with esomeprazole administration over 6 months and 62 healthy dogs to determine de novo reference interval (RI) of iMg. Dogs that received esomeprazole for 6 months or longer were retrospectively reviewed to determine the incidence of hypo- or hypermagnesemia based on the de novo RI. Additionally, the iMg levels from the study group were compared with those of 20 age-, sex-, and body weight-matched controls from the 62 dogs. The median (range) duration of esomeprazole usage was 26 months (6 to 94). The de novo RI for iMg was determined as 0.73 (90% CI, 0.58 to 0.87) to 1.43 mg/dL (90% CI, 1.33 to 1.46). Based on the RI, none of the dogs with long-term esomeprazole developed hypo- or hypermagnesemia. The iMg from the matched control group was 1.17 mg/dL (90% CI, 0.83 to 1.46). The lowest iMg after 6 months of esomeprazole administration (90% CI, 0.96 mg/dL, 0.87 to 1.41) was significantly lower than the control group (P = .031). The iMg measured at the end of long-term esomeprazole treatment was 1.03 mg/dL (90% CI, 0.87 to 1.41) and not significantly different from the control group (P = .179). Ionized hypomagnesemia was not observed after long-term use of esomeprazole in the small number of dogs included in this study. Robust RI needs to be determined in future studies to investigate the incidence of hypomagnesemia in dogs with long-term use of PPIs. Future studies in a larger number of dogs are warranted to confirm the findings from the present study and to determine whether the long-term use of esomeprazole in dogs is at risk of developing ionized hypomagnesemia.