Determining reference ranges for lymphocyte proliferation responses to phytohemagglutinin and Bacillus Calmette-Guérin in Iranian children.

PURPOSE: To establish reference ranges (RRs) for stimulation index of T cell proliferation triggered by phytohemagglutinin (PHA-SI) and Bacillus Calmette-Guérin (BCG-SI). METHODS: This study investigated data from 359 healthy children and 35 patients with cellular immunodeficiency as positive controls (2010-2021). We applied a colorimetric-based method (BrdU) to measure proliferation and determine the RRs at the 2.5th and 97.5th percentiles (95% confidence intervals). A cross-validation approach was performed. RESULTS: In healthy controls, the RRs for PHA-SI and BCG-SI ranged between 3 and 5.2 and 2.52 to 5.2, respectively. PHA-SI and BCG-SI were in Severe Combined Immunodeficiency (SCID) patients from 1.2 to 2.5 and 0 to 2, while in Mendelian susceptibility to mycobacterial diseases (MSMD) patients, 2.53 to 4.5 and 0.74 to 2.2, respectively. The thresholds' accuracy was checked for testing reference intervals with diagnostic effects. CONCLUSION: This study establishes PHA-SI and BCG-SI reference ranges to aid in diagnosing and treating congenital immunodeficiency diseases.

Reference Ranges for Arterial Oxygen Saturation, Heart Rate, and Cerebral Oxygen Saturation during Immediate Postnatal Transition in Neonates Born Extremely or Very Preterm.

OBJECTIVE: To define percentile charts for arterial oxygen saturation (SpO2), heart rate (HR), and cerebral oxygen saturation (crSO2) during the first 15 minutes after birth in neonates born very or extremely preterm and with favorable outcome. STUDY DESIGN: We conducted a secondary-outcome analysis of neonates born preterm included in the Cerebral regional tissue Oxygen Saturation to Guide Oxygen Delivery in preterm neonates during immediate transition after birth III (COSGOD III) trial with visible cerebral oximetry measurements and with favorable outcome, defined as survival without cerebral injuries until term age. We excluded infants with inflammatory morbidities within the first week after birth. SpO2 was obtained by pulse oximetry, and electrocardiogram or pulse oximetry were used for measurement of HR. crSO2 was assessed with near-infrared spectroscopy. Measurements were performed during the first 15 minutes after birth. Percentile charts (10th to 90th centile) were defined for each minute. RESULTS: A total of 207 neonates born preterm with a gestational age of 29.7 (23.9-31.9) weeks and a birth weight of 1200 (378-2320) g were eligible for analyses. The 10th percentile of SpO2 at minute 2, 5, 10, and 15 was 32%, 52%, 83%, and 85%, respectively. The 10th percentile of HR at minute 2, 5, 10, and 15 was 70, 109, 126, and 134 beats/min, respectively. The 10th percentile of crSO2 at minute 2, 5, 20, and 15 was 15%, 27%, 59%, and 63%, respectively. CONCLUSIONS: This study provides new centile charts for SpO2, HR, and crSO2 for neonates born extremely or very preterm with favorable outcome. Implementing these centiles in guiding interventions during the stabilization process after birth might help to more accurately target oxygenation during postnatal transition period.

MRI Reference Ranges for Fetal Cardiothoracic Ratio of Diameter, Area, and Circumference from 21 to 38 Weeks Gestational Age.

BACKGROUND: Whether fetal cardiothoracic ratio (CTR) is constant or increasing with gestational age (GA) is controversial. The majority of the fetal CTR data has been obtained through ultrasound. PURPOSE: To retrospectively analyze CTR of diameter, area, and circumference on prenatal MR images in a low-risk population of singleton pregnancies, and to clarify its diagnostic value. STUDY TYPE: Retrospective. SUBJECTS: 1024 low-risk singleton pregnancies undergoing MRI. FIELD STRENGTH: Balanced steady state free precession sequence and single shot-fast spin echo sequence at 1.5 Tesla. ASSESSMENT: Pregnancy clinical data were recorded and diameter, area, and circumference of the fetal heart and thorax were measured by two researchers with 6 and 7 years of radiology experience, respectively, and their variation with GA was investigated. The relationship between CTRs with GA was also investigated. Finally, the value of CTR in the diagnosis of fetuses with abnormal development was explored by using receiver operating characteristic (ROC) curves. STATISTICAL TESTS: Linear regression and ROC curves. A P value <0.05 was considered significant. RESULTS: There were significant positive linear correlations (R2 > 0.7, P < 0.0001) between the diameter, area, and circumference of the heart and thorax with GA. The CTRs remain constant values and do not change with GA. The 5th, 50th, and 95th percentiles of the CTR in 21-38 weeks GA were 0.32, 0.39, and 0.48 respectively. The corresponding percentiles for the area ratio were 0.15, 0.21 and 0.27, respectively, and for the circumference ratio were 0.40, 0.46, and 0.52, respectively. Based on ROC curves of CTR with three methods, the area under curves (AUCs) were up to 0.95, the sensitivity and the specificity were more than 88%. DATA CONCLUSION: Reference ranges of fetal CTR were established using MRI, which remain constant. These may be helpful in making a definitive diagnosis in fetuses with abnormal development. TECHNICAL EFFICACY: Stage 2.

Twenty-four-hour urinary protein excretion in uncomplicated singleton pregnancy.

BACKGROUND: Twenty-four-hour urinary total protein excretion is an essential parameter used for evaluation of renal function and early detection of gestational complications. However, data on reference ranges of 24-hour urinary total protein excretion in normal pregnancy are scarce. OBJECTIVE: This study aimed to determine reference ranges for 24-hour urinary total protein excretion in a population with uncomplicated singleton pregnancies using a standard method for urinary total protein. In addition, the values of 24-hour urinary total protein were stratified by maternal age and prepregnancy body mass index. STUDY DESIGN: This study was based on a prospective cohort study in Shenzhen, China. The pregnant women were enrolled at their first prenatal clinical visit. All the participants were instructed to collect 24-hour urine samples during the following successive gestational periods: 6+0 to 13+6, 14+0 to 27+6, and 28+0 to 41+6 weeks. Total urinary protein excretion was analyzed by a colorimetric method. Ultimately, the study encompassed a total of 4844 pregnant women with uncomplicated pregnancies. The nonparametric percentile method was used to determine reference ranges for 24-hour urinary total protein excretion during different trimesters in women with uncomplicated pregnancies (excluding those with previous kidney disorders, gestational or chronic hypertension, preeclampsia, and pregestational diabetes mellitus, among others). RESULTS: The 24-hour urinary total protein levels expressed as medians and percentiles (5th, 95th) for each trimester were as follows: 72.0 (28.4, 165.0), 88.0 (34.0, 185.0), and 108.0 (37.5, 258.0) mg in the first, second, and third trimesters, respectively. A significant increase in 24-hour urinary total protein excretion was observed throughout pregnancy (all P values <.001). Moreover, 24-hour urinary total protein levels were higher in the older (≥35 years) than in the younger (<35 years) group from mid-gestation. Specifically, the median (interquartile range) 24-hour urinary total protein levels by age were 72.2 (50.6-100.0) vs 70.5 (50.5-100.0) mg, 85.8 (62.0-117.0) vs 96.0 (68.0-127.8) mg, and 106.6 (76.0-146.2) vs 114.7 (81.5-153.6) mg in the first, second, and third trimesters, respectively. In addition, 24-hour proteinuria was significantly increased in higher-weight (overweight or obese) subgroups compared with lower-weight (underweight or normal-weight) subgroups (all P values <.05). CONCLUSION: Our study provides reference values for 24-hour urinary total protein excretion with apparently uncomplicated pregnancies. Understanding these changes in low-risk pregnancies is essential for optimizing maternal management.

Serum free light chains among twin siblings: is the kappa/lambda ratio genetically determined?

BACKGROUND: Serum kappa, lambda, the K/λ light chain concentrations are used for screening, diagnosis, and monitoring of patients with multiple myeloma and other plasma cell disorders. Biological variation studies conducted on healthy subjects showed that free light chains have a low within and high between-individual variation. We determined if this variation were genetically linked. METHODS: We obtained a single serum sample from 16 pairs of identical twins, 8 neonate twins, and 19 presumed directly-related siblings children, measured Κ and λ light chains and computed the Κ/λ ratio. RESULTS: As expected, Κ/λ results from each twin neonate were near identical (reflecting maternal/placental transfer). For older children and adult twins, the Κ/λ ratio form a cluster of results that were a subset of the reference range. There was one outlier, a female with a high, different from her twin sister. She likely had a monoclonal gammopathy (no followup was possible). Excluding this pair, results from neonate twins (14.4% ±10.3%) and non-neonate twins (18.0 ± 15.3%) were not significantly different. Results between non-twin siblings were more scattered (53.2%±53.4%) and different from neonate and non-neonate twin adult and children. CONCLUSION: We suggest that the Κ/λ free light chains may be genetically linked.

Reference ranges of peripheral-muscle oxygenation in term neonates delivered by Caesarean section during immediate transition after birth.

AIM: To establish reference ranges of peripheral-muscle regional oxygen saturation (prSO2) and peripheral fractional tissue oxygen extraction (pFTOE) during the first 15 min after birth in stable term neonates. METHODS: Secondary outcome parameters of prospective observational studies in healthy term neonates delivered by Caesarean section were analysed. prSO2 was measured on the right forearm using the INVOS 5100C monitor. pFTOE was calculated out of prSO2 and arterial oxygen saturation (SpO2). Centile charts (10th-90th) of prSO2 and pFTOE were defined during the first 15 min after birth. RESULTS: Three-hundred-five term neonates with a mean gestational age and birth weight of 39.0 ± 0.9 weeks and 3321 ± 454 g, respectively, were included. The 50th centiles of prSO2 were 39% (minute two), 52% (minute five), 71% (minute 10), and 73% (minute 15). The 50th centiles of pFTOE were 0.529 (minute two), 0.378 (minute five), 0.237 (minute 10), and 0.231 (minute 15). CONCLUSION: Reference ranges of prSO2 and pFTOE were established for term neonates delivered by Caesarean section during the immediate transition after birth. These reference ranges increase knowledge of physiological processes taking place immediately after birth and are necessary for possible future clinical applications.

Age-related changes in hematological biomarkers in common marmosets.

Researchers and veterinarians often use hematology and clinical chemistry to evaluate animal health. These biomarkers are relatively easy to obtain, and understanding how they change across healthy aging is critical to clinical care and diagnostics for these animals. We aimed to evaluate how clinical biomarkers from a chemistry profile and complete blood count (CBC) change with age in common marmosets (Callithrix jacchus). We assessed blood samples collected during routine physical exams at the Southwest National Primate Research Center and the University of Texas Health San Antonio marmoset colonies from November 2020-November 2021. We found that chemistry and CBC profiles varied based on facility, sex, and age. Significant changes in albumin, phosphorus/creatinine ratio, albumin/globulin ratio, amylase, creatinine, lymphocyte percent, hematocrit, granulocytes percent, lymphocytes, hemoglobin, red cell distribution width, and platelet distribution width were all reported with advancing age. Aged individuals also demonstrated evidence for changes in liver, kidney, and immune system function compared with younger individuals. Our results suggest there may be regular changes associated with healthy aging in marmosets that are outside of the range typically considered as normal values for healthy young individuals, indicating the potential need for redefined healthy ranges for clinical biomarkers in aged animals. Identifying animals that exhibit values outside of this defined healthy aging reference will allow more accurate diagnostics and treatments for aging colonies.

Characterization of ophthalmic lesions and normal ocular parameters in a flock of captive MacQueen's (houbara) bustards (Chlamydotis macqueenii).

OBJECTIVES: To determine normal ocular parameters of the MacQueen's bustard (Chlamydotis macqueenii) and describe ophthalmic lesions in a captive bred population. ANIMALS STUDIED: Captive breeding population of 257 Macqueen's bustards. METHODS: All birds were screened for ocular abnormalities using direct ophthalmoscopy. Abnormalities were photographed. Normative values for Schirmer tear test-1 (STT-1), applanation tonometry, aerobic and anaerobic bacterial culture, fungal culture, and transcorneal ocular ultrasonography were derived from multiple cohorts of clinically normal adult birds. Five birds with ocular pathology also underwent transcorneal ultrasonography. Statistical comparisons for normative values between OD and OS, and males and females were made using a paired t-test or Mann-Whitney U-test, with a significance level of p < .05. RESULTS: Mean tear production based on Schirmer tear test 1 (STT-1) was 10.16 ± 4.61 mm/min (3-21 mm/min). Mean intraocular pressure (IOP) was 12.42 ± 4.94 mm Hg (5-26 mm Hg). Staphylococcus species were the most isolated bacteria from the conjunctival surfaces of normal birds (85%). Significant differences were found in transcorneal ultrasonographic measurements between males and females for axial globe length (p = .032), vitreous body depth (p = .049) and lens thickness (p = .0428). Corneal fibrosis was the most observed ocular abnormality amongst eyes with pathological changes (39%). CONCLUSIONS: Schirmer tear testing, tonometry and transcorneal ultrasound can easily be utilized in MacQueen's bustards and provide reproducible results. Normal parameters for these tests were determined, and common pathological ocular changes were described in this species.

Reference Ranges for Left Modified Myocardial Performance Index: Systematic Review and Meta-Analysis.

INTRODUCTION: The modified myocardial performance index (mod-MPI) is a noninvasive Doppler-derived metric used to evaluate fetal cardiac function. However, the reference ranges for mod-MPI in normal fetuses are not clearly defined, which limits the use of this technology in fetuses with potential cardiac compromise. Thus, we aimed to perform a systematic review and meta-analysis of published mod-MPI reference ranges across gestation. METHODS: The published literature was systematically searched, and all published articles in any language that provided values for the left ventricular mod-MPI obtained in low-risk, singleton fetuses were considered eligible for further review. All retrieved titles and abstracts were independently reviewed by two researchers. Mean and standard deviation by gestational week was extracted or calculated from published data. DerSimonian-Laird random-effects models were used to estimate pooled means and 95% confidence intervals (CIs). RESULTS: The search resulted in 618 unique citations, of which 583 did not meet inclusion criteria, leaving 35 abstracts selected for full-text review. Review of the references of these 35 articles identified another 5 studies of interest. Of the 40 articles reviewed, six met inclusion criteria. There was significant heterogeneity seen in the mod-MPI results reported. Mod-MPI increased as pregnancy progressed in all studies. The pooled mean mod-MPI at 11 weeks' gestation was 0.400 (95% CI 0.374-0.426) and increased to 0.585 (95% CI 0.533-0.637) at 41 weeks' gestation. The increase was linear in 5 of 6 studies, while in 1 study, the mod-MPI was stable until 27 weeks' gestation, and then increased throughout the third trimester. Despite all having trends increasing over pregnancy, there was no study in which all the weekly means fell within the pooled 95% CI. CONCLUSION: While mod-MPI does increase over gestation, the true "reference ranges" for fetuses remain elusive. Future efforts to further optimize calculation of time intervals possibly via automation are desperately needed to allow for reproducibility of this potentially very useful tool to assess fetal cardiac function.

Dynamics of serum levels and reference ranges of copeptin in the 3rd trimester of pregnancy in healthy pregnant women with uncomplicated pregnancy and delivery.

OBJECTIVE: Copeptin is a stable fragment of vasopressin. Copeptin levels have been found to reflect the degree of endothelial stress in various conditions, including acute coronary syndrome. Copeptin may be a bio marker for endothelial stress during pregnancy. However, there is still a lack of understanding of its dynamics and levels throughout pregnancy. This study aims to describe intra-individual and longitudinal changes in copeptin levels at 30th and 36th gestational weeks in healthy pregnant women with uncomplicated pregnancy and delivery and to establish specific reference ranges. METHODS: A total of 125 pregnant women with uncomplicated pregnancy and delivery were included. These women were monitored throughout their pregnancy and gave birth at the Department of Obstetrics and Gynecology Olomouc University Hospital. The blood was taken at ~30 and ~36 gestational weeks. Serum copeptin levels were measured using a Kryptor Compact PLUS analyzer. For statistics, we used R software and the "referenceRanges" package. RESULTS: It was found that serum levels of copeptin were significantly higher in the 36th week group than in the 30th week group (P < 0.05). Cook's distance was used to eliminate outliers. The 30th week median was 3.377 pmol/l, reference range = 1.343-7.829 pmol/l, and the 36 week was median 4.735 pmol/l and reference range = 2.06-13.2 pmol/l. In the 36th week reference range, the median was higher than in healthy, non-pregnant women (P < 0.05). Copeptin values can exceed 10 pmol/l, particularly after the 36th week. In the 3rd trimester, this value may indicate cardiovascular and endothelial overload. CONCLUSION: Copeptin levels were found to vary significantly depending on gestational week. The proposed reference ranges take into account the increased secretion of vasopressin in pregnancy. The existence of specific upper reference limits represents a potential advantage in detecting pregnant women prone to hypertensive disease in the 3rd trimester.

Reference ranges of fetal cisterna magna volume measurements by three-dimensional ultrasonography in the late second trimester considering sonographic experience.

BACKGROUND: Volume measurements of fetal cisterna magna (CM) by three-dimensional (3D) ultrasonography may have a role in the diagnosis of various posterior fossa abnormalities. PURPOSE: To evaluate reference intervals and reliability of fetal CM volume values by virtual organ computer-aided analysis (VOCAL) in structurally normal fetuses, considering experience of evaluators. MATERIAL AND METHODS: Three operators with different 3D sonography experience levels measured CM volumes of 100 structurally normal fetuses at 18-27 weeks of gestation. Reference intervals for CM volumes were generated. Intraclass correlation coefficients (ICC) were calculated. RESULTS: Mean fetal CM volume measurements by the three operators did not significantly (P = 0.49, P = 0.22, and P = 0.17, respectively) change through 20-23 weeks of gestation. Moderate degrees of inter-observer reliability were found with an ICC of 0.69 between novice and intermediate-level, ICC of 0.74 between experienced and intermediate-level, and ICC of 0.78 between experienced and novice observer, respectively. The novice sonographer generally overestimated CM measurements. Intra-observer reliability was good (ICC=0.85). CONCLUSION: A reference chart for fetal CM volume by VOCAL was formed, revealing uniform mean values of 20-23 weeks of gestation. The inter-observer reliability is moderate, and biases seem relatively common for all experience categories.

Modeling fetal cavum septum pellucidi width by quantile regression at 18-34 weeks of gestation: A prospective cross-sectional study.

OBJECTIVE: Develop charts for cavum septum pellucidi (CSP) following a standardized methodology and using quantile regression. The secondary objective was to assess the influence of fetal gender on the generated reference curves. METHODS: In a cross-sectional prospective study 453 low-risk singleton pregnancies were evaluated at a gestational age interval between 18 and 34 weeks. The width of CSP were measured on ultrasound images using a standardized technique and their changes were evaluated by quantile regression as a function of gestational age (GA) interval or head circumference (HC). Differences between sex were evaluated. RESULTS: The measurement of CSP significantly increased with gestation and HC. Linear models better described the changes of CSP with GA and HC. The fits of CSP width with GA and HC were not significantly different. Male fetuses showed significantly higher CSP width when compared to female fetuses (u = 2.973; p = 0.005). CONCLUSIONS: We generated prospective nomograms of fetal CSP development using quantile regression and following a strict standardized methodology. These new charts may be useful to better identify abnormal cases at higher risk of associated anomalies. Further our findings underline the potential effect of gender in developing fetal brain.

Reference Range of Plasma Fatty Acids in North Indian Pregnant Population.

Reference values for Fatty Acids (FAs) are not well defined in the Indian population. Therefore, it is critical to establish FAs reference range for the healthy non-pregnant and pregnant Indian population. The present multi-centric, and cross-sectional study determines the 95% reference interval for FAs in an apparently pregnant Indian population and compare it to the healthy non-pregnant women. Physicians identified 164 reference individuals as healthy (56 non-pregnant and 108 pregnant) at various government and private hospitals of northern India. The 95th and 97.5th percentile reference limits were used to estimate the 95 percentile of the reference distribution. The reference ranges observed for Alpha-linolenic acid (0.29-0.42%; 0.36-0.58%), Docosahexaenoic-acid (3.38-4.23%; 3.8-4.55%), Eicosapentaenoic-acid (1.24-1.76%; 1.09-1.62%), Docosapentaenoic-acid-3 (0.61-0.69%; 0.65-0.76%), Linoleic-acid (18.44-20.75%; 19.51-21.88%), gamma-linolenic-acid (0.24-0.35%; 0.32-0.42%), Eicosatrienoic-acid (0.26-0.32%; 0.34-0.39%), Arachidonic-acid (9.29-11.02%; 10.02-11.56%), Docosatetraenoic-acid (0.62-0.89%; 0.79-1.09%), Docosapentaenoic-acid-6 (0.23-0.31%; 0.33-0.41%), Eicosatrienoic-acid (1.17-1.41%; 1.43-1.74%), Eicosenoic-acid (0.28-0.38%; 0.37-0.49%), Nervonic-acid (1.39-1.69%; 1.41-1.74%), Palmitoleic-acid (1.17-1.58%; 2-2.66%), Oleic-acid (19.8-22.26%; 19.68-22.94%), Myristic-acid (1.16-1.68%; 0.82-1.3%), Palmitic-acid (20.05-21.8%; 20.7-22.43%), Stearic-acid (11.34-12.56%; 10.29-11.02%), Arachidic-acid (0.17-0.2%; 0.18-0.23%), Lignoceric-acid (0.81-1.08%; 0.77-1.08%), trans-palmitoleic-acid (0.22-0.29%; 0.26-0.37%), trans-oleic-acid (0.55-0.72%; 0.68-0.84%), trans-linoleic-acid (0.38-0.54%; 0.42-0.59%) respectively for non-pregnant and pregnant women. Furthermore, total FAs were significantly (p ≤ 0:05) higher in women aged 31-45 years than in women aged 16-30 years. whereas, there was no significant change in total FAs profile based on omega-supplementation, diet category, preterm-birth history, and gestation period. Thus, the current study provides information about an individual who is deficient in FAs and the dose required to increase FA concentrations in the body.

Intrahepatic cholestasis of pregnancy - Time to redefine the reference range of total serum bile acids: A cross-sectional study.

OBJECTIVE: To establish pregnancy-specific reference ranges for fasting and postprandial total serum bile acid (TSBA) concentrations. DESIGN: Cross-sectional study. SETTING: Tertiary-care university hospital. POPULATION: Healthy pregnant women at term admitted to the Obstetrics Department over a period of 1 year. Exclusion criteria were an established diagnosis of intrahepatic cholestasis of pregnancy (ICP) or any coexisting condition of increased risk for ICP. METHODS: Both fasting (after 8-14 h of fasting) and postprandial (2 h after meal) TSBA concentrations were measured in 612 women (with 528 fasting samples and 377 postprandial samples) by automated enzymatic spectrophotometric assay. MAIN OUTCOME MEASURES: Fasting and postprandial TSBA concentrations in 612 women. RESULTS: Reference intervals of 4.4-14.1 µmol/L for fasting TSBA and 4.7-20.2 µmol/L for postprandial TSBA were established. The postprandial values were significantly higher than the fasting values, with a median increase of 1.0 µmol/L (p < 0.0001). A correlation between fasting TSBA concentrations and postprandial concentrations was found, as well as correlations with fetal sex, parity and assisted reproductive technologies. A seasonal pattern was noticed for both fasting and postprandial TSBA, with the highest values measured in the winter season (p < 0.01 and 0.02, respectively) CONCLUSIONS: Normal pregnancy is associated with mild hypercholanaemia, and therefore a higher threshold should be considered for the diagnosis of ICP. We suggest using the upper reference limits observed in our healthy pregnant population (14 µmol/L for fasting TSBA and 20 µmol/L for postprandial TSBA). As the fasting measurement is more specific for the diagnosis, and the postprandial measurement is essential for the assessment of severity, it is recommended to measure both values rather than use random sampling. TWEETABLE ABSTRACT: Normal pregnancy is associated with mild hypercholanaemia, a higher threshold should be considered for the diagnosis of ICP.

Reference ranges for GDF-15, and risk factors associated with GDF-15, in a large general population cohort.

OBJECTIVES: Growth differentiation factor (GDF)-15 is attracting interest as a biomarker in several areas of medicine. We aimed to evaluate the reference range for GDF-15 in a general population, and to explore demographics, classical cardiovascular disease risk factors, and other cardiac biomarkers associated with GDF-15. METHODS: GDF-15 was measured in serum from 19,462 individuals in the Generation Scotland Scottish Family Health Study. Associations of cardiometabolic risk factors with GDF-15 were tested using adjusted linear regression. Among 18,507 participants with no heart disease, heart failure, or stroke, and not pregnant, reference ranges (median and 97.5th centiles) were derived by decade age bands and sex. RESULTS: Among males in the reference range population, median (97.5th centile) GDF-15 concentration at age <30 years was 537 (1,135) pg/mL, rising to 931 (2,492) pg/mL at 50-59 years, and 2,152 (5,972) pg/mL at ≥80 years. In females, median GDF-15 at age <30 years was 628 (2,195) pg/mL, 881 (2,323) pg/mL at 50-59 years, and 1847 (6,830) pg/mL at ≥80 years. Among those known to be pregnant, median GDF-15 was 19,311 pg/mL. After adjustment, GDF-15 was higher in participants with adverse cardiovascular risk factors, including current smoking (+26.1%), those with previous heart disease (+12.7%), stroke (+17.1%), heart failure (+25.3%), and particularly diabetes (+60.2%). GDF-15 had positive associations with cardiac biomarkers cardiac troponin I, cardiac troponin T, and N-terminal pro B-type natriuretic peptide (NT-proBNP). CONCLUSIONS: These data define reference ranges for GDF-15 for comparison in future studies, and identify potentially confounding risk factors and mediators to be considered in interpreting GDF-15 concentrations.

Serum free light chain analysis: persisting limitations with new kids on the block.

OBJECTIVES: Serum free light chain (sFLC) measurements have inherent analytical limitations impacting sFLC clinical interpretation. We evaluated analytical and diagnostic performance of three polyclonal sFLC assays on four analytical platforms. METHODS: sFLC concentration was measured using Diazyme FLC assays (Diazyme) on cobas c501/c503 analyzer (Roche); Freelite assays (The Binding Site) on Optilite analyzer (The Binding Site) and cobas c501 analyzer and Sebia FLC ELISA assays (Sebia) on AP22 ELITE analyzer (DAS). Imprecision, linearity, method comparison vs. Freelite/Optilite, antigen excess detection and reference value verification were assessed. Diagnostic performance was compared on 120 serum samples and on follow-up samples of five patients with κ and λ monoclonal gammopathy. RESULTS: Method comparison showed excellent correlation with Freelite/Optilite method for all assays. A large proportional negative bias was shown for both Sebia κ and λ ELISA and a significant positive proportional bias for λ in the low (<10 mg/L) Freelite/cobas c501 method. Clinically relevant underestimation of κ sFLC levels due to antigen excess was shown for 7% of each Diazyme/cobas application and for 11 and 32.1% of λ sFLC assay of respectively Diazyme/cobas and Sebia/AP22. sFLC reference values revealed application specific. Cohen's κ values were (very) good for κ sFLC but only moderate to good for λ sFLC. In 4/10 follow-up patients, significant differences in clinical interpretation between sFLC assays were noticed. CONCLUSIONS: Important analytical limitations remain for all sFLC applications. Differences in reference values and diagnostic performance hamper interchangeability of sFLC assays. Assay specific sFLC decision guidelines are warranted.

MERCI: a machine learning approach to identifying hydroxychloroquine retinopathy using mfERG.

PURPOSE: Hydroxychloroquine (HCQ) is an anti-inflammatory drug in widespread use for the treatment of systemic auto-immune diseases. Vision loss caused by retinal toxicity is a significant risk associated with long term HCQ therapy. Identifying patients at risk of developing retinal toxicity can help prevent vision loss and improve the quality of life for patients. This paper presents updated reference thresholds and examines the diagnostic accuracy of a machine learning approach for identifying retinal toxicity using the multifocal Electroretinogram (mfERG). METHODS: A retrospective study of patients referred for mfERG testing to detect HCQ retinopathy. A consecutive series of all patients referred to Kensington Vision and Research Centre between August 2017 and July 2020 were considered eligible. Eyes suspect for other ocular pathology including widespread retinal disease and advanced macular pathology unrelated to HCQ or with poor quality mfERG recordings were excluded. All patients received mfERG testing and Ocular Coherence Tomography (OCT) imaging. Presence of HCQ retinopathy was based on ring ratio analysis using clinical reference thresholds established at KVRC coupled with structural features observed on OCT, the clinical reference standard. A Support Vector Machine (SVM) using selected features of the mfERG was trained. Accuracy, sensitivity and specificity are reported. RESULTS: 1463 eyes of 748 patients were included in the study. SVM model performance was assessed on 293 eyes from 265 patients. 55 eyes from 54 patients were identified as demonstrating HCQ retinopathy based on the clinical reference standard, 50 eyes from 49 patients were identified by the SVM. Our SVM achieves an accuracy of 85.3% with a sensitivity of 90.9% and specificity of 84.0%. CONCLUSIONS: Machine learning approaches can be applied to mfERG analysis to identify patients at risk of retinopathy caused by HCQ therapy.

Gestational age-based reference ranges for cervical length and preterm birth prediction in triplet pregnancies: an observational retrospective study.

OBJECTIVES: To develop gestational age-based reference ranges for cervical length in triplet pregnancies. The secondary objective was to assess the performance of cervical length measured between 18 and 20 + 6 days for the prediction of preterm delivery before 28 and 32 weeks, respectively. METHODS: Observational retrospective study of triplet pregnancies in three Spanish tertiary-care hospitals between 2001 and 2019. Cervical length measurements were consecutively obtained between 15 and 34 weeks of gestation. Pregnancies undergoing multifetal reduction or fetal surgery were excluded. RESULTS: Two hundred and six triplet pregnancies were included in the final analysis. There was a quadratic decrease in cervical length with gestational age. The median and fifth centiles for cervical length at 20 weeks were 35 and 13 mm. In the prediction of preterm birth < 28 weeks, for a false positive rate of 5%, and 10%, the detection rates were 40.9%, and 40.9%, respectively, and the prediction of preterm birth < 32 weeks, 22.0% and 26.0%, respectively. CONCLUSIONS: In triplet pregnancies, cervical length decreases with gestational age. The performance of cervical length at 18-20 + 6 in screening for preterm birth before 28 and 32 weeks is poor.

Development of quantitative assay for simultaneous measurement of purine metabolites and creatinine in biobanked urine by liquid chromatography-tandem mass spectrometry.

Purine metabolism is essential for all known living creatures, including humans in whom elevated serum concentration of purine break-down product uric acid (UA) is probably an independent risk factor for mortality, type 2 diabetes and cardiovascular events. An automated multiplex assay that measures several purine metabolites could therefore prove useful in many areas of medical, veterinary and biological research. The aim of the present work was to develop a sensitive LC-MS/MS method for simultaneous quantitation of xanthine, hypoxanthine, UA, allantoin, and creatinine in biobanked urine samples. This article describes details and performance of the new method studied in 55 samples of human urine. Archival sample preparation and effect of storage conditions on stability of the analytes are addressed. The intra-day and inter-day coefficients of variation were small for all the analytes, not exceeding 1% and 10%, respectively. Measurements of UA and creatinine in biobanked urine showed good agreement with values obtained using routine enzymatic assays on fresh urine. Spearman's correlation coefficients were 0.869 (p < .001) for creatinine and 0.964 (p < .001) for UA. Conclusion: the newly developed LC-MS/MS method allows reliable quantitative assessment of xanthine, hypoxanthine, allantoin, UA and creatinine. The proposed pre-analytical processing makes the method suitable for both fresh and biobanked urine stored frozen at -80 °C for at least 5.5 years.

Multicenter performance evaluation and reference range determination of a new one-stage factor VIII assay.

INTRODUCTION: We conducted a multicenter evaluation of a new one-stage factor VIII (FVIII) assay (Roche Diagnostics), intended for the quantitative assessment of FVIII activity. We evaluated the analytical performance of the FVIII assay on the cobas t 711 analyzer. METHODS: Experiments performed at three laboratories used 3.2% citrated residual or commercially purchased plasma samples. Five human plasma pools and two controls were used to determine assay within-run and within-laboratory precision, and total reproducibility; coefficients of variation (CVs) and/or standard deviations (SDs) were calculated. Lot-to-lot variability and method comparison (vs Coagulation FVIII Deficient Plasma/Dade Actin FS Activated PTT reagent/Standard Human Plasma Calibrator on the Sysmex CS-5100 analyzer; Siemens Healthineers) were evaluated by Passing-Bablok and Deming regression, respectively, and Pearson's r calculated. Assay-specific reference range was determined using 199 fresh plasma samples from healthy adults, not receiving anticoagulants. RESULTS: Across sites, SDs for repeatability were 0.016-0.046 for samples with ≤1.0 international units (IU)/dL FVIII activity; CVs were 0.9%-3.8% for samples with >1.0 IU/dl activity. Among samples with mean FVIII activity 0.344-133 IU/dl, good intermediate precision (SD 0.020 for samples with 0.344 IU/dl activity; CV 1.8%-4.7%) and good total reproducibility (CV 2.0%-13.3%) were observed. The FVIII assay showed excellent lot-to-lot variability (Pearson's r = .999) and good correlation with the comparator assay (Pearson's r = .993-.996). The reference range for FVIII activity was 82.2-218.0 IU/dl. CONCLUSION: The one-stage FVIII assay demonstrated robust analytical performance on the cobas t 711 analyzer, supporting its use in routine laboratory practice.