Age-specific Reference Intervals Research Articles

Quantitative analysis of ethanolamine plasmalogen species in red blood cells using liquid chromatography tandem mass spectrometry for diagnosing peroxisome biogenesis disorders

Plasmalogens are glycerophospholipids characterized by a vinyl-ether bond with a fatty alcohol at the sn-1 position, a polyunsaturated fatty acid at the sn-2 position, and a polar head at the sn-3 position, commonly phosphoethanolamine. Plasmalogens play crucial roles in several cellular processes. Reduced levels have been associated with Alzheimer’s and Parkinson’s disease progression. Markedly reduced plasmalogens are a classic feature of peroxisome biogenesis disorders (PBD) because plasmalogen synthesis requires functional peroxisomes. Particularly, severe plasmalogen deficiency is the biochemical hallmark of rhizomelic chondrodysplasia punctata (RCDP). Traditionally, plasmalogens are evaluated in red blood cells (RBCs) by gas-chromatography/mass-spectrometry (GC–MS), which cannot distinguish individual species. We developed a liquid-chromatography/tandem mass-spectrometry (LC-MS/MS) method to quantify eighteen phosphoethanolamine plasmalogens in RBCs to diagnose PBD patients, especially RCDP. Validation results showed a specific, robust, and precise method with broad analytical range. Age-specific reference intervals were established; control medians were used to assess plasmalogen deficiency in patients’ RBCs. Clinical utility was also confirmed in Pex7 deficient mouse models recapitulating severe and milder RCDP clinical phenotypes. To our knowledge, this is the first attempt to replace the GC–MS method in the clinical laboratory. In addition to diagnosing PBDs, structure-specific plasmalogen quantitation could help understand disease pathogenesis and monitor therapy.

Reference Intervals for Plasma Free Kappa and Lambda Chains and Kappa/Lambda Ratio using PENIA.

Determination of free light chains is used increasingly for patients with multiple myeloma and other plasma cell dyscrasias. The aim of the present study was to define reference intervals for free kappa and lambda chains and kappa/lambda ratio in lithium heparin plasma and compare the test results with cystatin C based estimated glomerular filtration rate. Free kappa and lambda chains were measured in Liheparin plasma from 222 healthy blood donors using free light chain reagents and a BNII nephelometer from Siemens Diagnostics. Calculated reference intervals for kappa chain, free was 4.73 mg/L (90% confidence interval 4.00 - 5.45) - 22.66 mg/L (20.33 - 24.98), for lambda chain, free was 4.33 mg/L (3.70 - 4.95) - 29.28 mg/L (26.96 - 31.59), and for Kappa/Lambda Chain ratio 0.59 (0.56 - 0.62) - 1.46 (1.37 - 1.56). There was no need for gender or age specific reference intervals. Cystatin C based estimated glomerular filtration rate had a significant effect on the levels of free light chains. The study presents reference intervals for plasma free light chains and compared results of estimated glomerular filtration rate with free light chains of kappa and lambda.

Verification of sex- and age-specific reference intervals for 13 serum steroids determined by mass spectrometry: evaluation of an indirect statistical approach.

Conventionally, reference intervals are established by direct methods, which require a well-characterized, obviously healthy study population. This elaborate approach is time consuming, costly and has rarely been applied to steroid hormones measured by mass spectrometry. In this feasibility study, we investigate whether indirect methods based on routine laboratory results can be used to verify reference intervals from external sources. A total of 11,259 serum samples were used to quantify 13 steroid hormones by mass spectrometry. For indirect estimation of reference intervals, we applied a "modified Hoffmann approach", and verified the results with a more sophisticated statistical method (refineR). We compared our results with those of four recent studies using direct approaches. We evaluated a total of 81 sex- and age-specific reference intervals, for which at least 120 measurements were available. The overall agreement between indirectly and directly determined reference intervals was surprisingly good as nearly every fourth reference limit could be confirmed by narrow tolerance limits. Furthermore, lower reference limits could be provided for some low concentrated hormones by the indirect method. In cases of substantial deviations, our results matched the underlying data better than reference intervals from external studies. Our study shows for the first time that indirect methods are a valuable tool to verify existing reference intervals for steroid hormones. A simple "modified Hoffmann approach" based on the general assumption of a normal or lognormal distribution model is sufficient for screening purposes, while the refineR algorithm may be used for a more detailed analysis.

Red blood cell parameters in early childhood: a prospective cohort study.

Red blood cell parameters are frequently used biomarkers when assessing clinical status in newborns and in early childhood. Cell counts, amounts, and concentrations of these parameters change through gestation and after birth. Robust age-specific reference intervals are needed to optimize clinical decision making. The Copenhagen Baby Heart Study (CBHS) and the COMPARE study are prospective cohort studies including red blood cell parameters from 7,938 umbilical cord blood samples and 295 parallel venous blood samples from newborns with follow-up at two and at 14-16months after birth. For venous blood at birth, reference intervals for hemoglobin, erythrocytes, and hematocrit were 145-224g/L, 4.1-6.4×1012/L, and 0.44-0.64, respectively. Hemoglobin, erythrocytes, and hematocrit were lower at birth in children delivered by prelabor cesarean section compared to vaginal delivery. Conversion algorithms based on term newborns were: venous hemoglobin=(umbilical cord hemoglobin-86.4)/0.39; venous erythrocytes=(umbilical cord erythrocytes-2.20)/0.44; and venous hematocrit=(umbilical cord hematocrit-0.24)/0.45. This study presents new reference intervals for red blood cell parameters in early childhood, describes the impact of delivery mode, and provide exact functions for converting umbilical cord to venous blood measurements for term newborns. These findings may improve clinical decision making within neonatology and infancy and enhance our clinical understanding of red blood cell parameters for health and diseases in early life.

Reference Interval for Serum L-Homoarginine Determined with Enzyme-Linked Immunosorbent Assay in the Population-Based Study of Health in Pomerania.

Low levels of the endogenous amino acid L-homoarginine are a risk factor for cardiovascular morbidity and mortality. For individual risk prediction, commercially available test systems are mandatory. This study aims at formulating sex- and age-specific reference intervals of serum L-homoarginine determined with an ELISA. We determined reference intervals for serum L-homoarginine stratified by age and sex in a sample of 1285 healthy participants of the Study of Health in Pomerania (SHIP)-TREND cohort after exclusion of participants with cardiovascular diseases, diabetes mellitus, hypertension, metabolic syndrome, elevated liver enzymes, chronic kidney disease stages III or IV, or body mass index >25 kg/m2. Serum L-homoarginine was determined applying a commercially available ELISA. The reference cohort included 836 women (median age 41, 25th and 75th percentiles are 32 and 50 years) and 449 men (median age 38, 25th, and 75th percentiles are 30 and 49 years). The median serum concentration of L-homoarginine was 1.93 (25th 1.49; 75th 2.60) µmol/L in women and 2.02 (25th 1.63; 75th 2.61) µmol/L in men (P = 0.04). The reference intervals (2.5th to 97.5th percentile) were 0.89-5.29 µmol/L for women and 1.09-3.76 µmol/L for men. The L-homoarginine serum concentration declined over age decades in both sexes and a notable interaction with sex hormone intake in women was observed. The novelty of our study is that we determined reference intervals specific for the L-isomer being lower than those previously reported for homoarginine in SHIP and thus might be helpful in identifying individuals suitable for oral L-homoarginine supplementation.

Chinese normotensive and essential hypertensive reference intervals for plasma aldosterone and renin activity by liquid chromatography-tandem mass spectrometry.

The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure. Plasma renin activities (PRA) and plasma aldosterone concentrations (PAC) are biomarkers related to RAAS. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based measurements for PRA and PAC have become popular. Method-specific reference intervals (RIs) are required. Routine PRA and PAC services in a Hong Kong teaching hospital were based on LC-MS/MS methods. PRA and PAC RIs were developed for normotensive subjects and essential hypertensive (EH) patients. Healthy volunteers were recruited to establish normotensive RIs. PRA and PAC results of hypertensive patients with urine aldosterone tests for primary aldosteronism (PA) screening were retrieved from the laboratory information system. Patients without PA were included. Patients with secondary hypertension and patients on medications affecting the RAAS were excluded. The central 95% RIs were established based on the recommendations of the Clinical and Laboratory Standards Institute guideline C28-A3. PRA and PAC of 170 normotensive volunteers and 362EH patients were analysed. There was no sex-specific difference in PRA and PAC for normotensive and EH reference subjects. Differences for PRA and PAC were noted between normotensive subjects aged below 45 and their older counterparts. However, such a difference was only identified for PRA but not PAC in EH patients. Age-specific RIs were established accordingly. This study presented age-specific LC-MS/MS RIs of PRA and PAC for both normotensive and EH populations for local Chinese in Hong Kong.

Derivation of sex and age-specific reference intervals for clinical chemistry analytes in healthy Ghanaian adults.

This study is aimed at establishing reference intervals (RIs) of 40 chemistry and immunochemistry analytes for Ghanaian adults based on internationally harmonized protocol by IFCC Committee on Reference Intervals and Decision Limits (C-RIDL). A total of 501 healthy volunteers aged≥18 years were recruited from the northern and southern regions of Ghana. Blood samples were analyzed with Beckman-Coulter AU480 and Centaur-XP/Siemen auto-analyzers. Sources of variations of reference values (RVs) were evaluated by multiple regression analysis (MRA). The need for partitioning RVs by sex and age was guided by the SD ratio (SDR). The RI for each analyte was derived using parametric method with application of the latent abnormal values exclusion (LAVE) method. Using SDR≥0.4 as threshold, RVs were partitioned by sex for most enzymes, creatinine, uric acid (UA), bilirubin, immunoglobulin-M. MRA revealed age and body mass index (BMI) as major source of variations of many analytes. LAVE lowered the upper limits of RIs for alanine/aspartate aminotransferase, γ-glutamyl transaminase and lipids. Exclusion of individuals with BMI≥30 further lowered the RIs for lipids and CRP. After standardization based on value-assigned serum panel provided by C-RIDL, Ghanaian RIs were found higher for creatine kinase, amylase, and lower for albumin and urea compared to other collaborating countries. The LAVE effect on many clinical chemistry RIs supports the need for the secondary exclusion for reliable derivation of RIs. The differences in Ghanaian RIs compared to other countries underscore the importance ofcountry specific-RIs for improved clinical decision making.

Pediatric reference intervals for Free Testosterone, 17-OH Progesterone, Androstenedione, and IGF-1 with chemiluminescence immunoassay

BackgroundThe aim of the study was to produce age and sex specific pediatric reference intervals (RIs) on a fully automated chemiluminescent immunoassay (CLIA) system. Material and methodA total of 1586 patients’ remnant sera were included in the study and free testosterone (FT), 17-OH progesterone (17OHP), androstenodione (A4) and insulin-like growth factor-1 (IGF-1) parameters were measured on MAGLUMI 2000 (Shenzhen New Industries Biomedical Engineering Co., Ltd. (Snibe), Shenzhen, China) CLIA analyser. After appropriate age and gender partitioning, specific intervals were calculated according to Clinical Laboratory Standart Institute’s (CLSI) C28-A3 protocol. ResultsAll analytes showed sex and age dependent concentrations requiring several subgroups with specific reference intervals. 17OHP and A4 were found high with birth, declined thereafter: 17OHP by the end of 12 months and A4 by 6 months. So this period was also partitioned for these two hormones. All showed gradual increases by the end of 18 years. 17OHP, A4 and IGF-1 of girls were higher than boys around puberty as the result of earlier sexual development and maturation. FT values of boys and girls didn’t differ from each other upto 10 years of age but boys had significantly higher values than girls afterwards. IGF-1 values gradually increase in both sexes upto the ages of 13, girls with significantly higher values than boys. In 13–18 years no significant gender difference was found. ConclusionsWe present method specific pediatric RIs, which are comparable with medical literature, necessary for interpretation of patient results.

Establishment of gender- and age-specific reference intervals for serum liver function tests among the elderly population in northeast China: a retrospective study.

IntroductionReference intervals (RIs) for younger population may not apply to the elderly population. The aim of this study was to establish gender- and age-specific RIs for serum liver function tests among the elderly population and to compare with younger population RIs currently used in China and other countries.Materials and methodsThis was a retrospective study, and subjects (≥ 18 year-old) were recruited from the laboratory information system (LIS) at the First Hospital of Jilin University between April 2020 and April 2021. The following parameters were collected: aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), total protein (TP), albumin (ALB), total bilirubin (TBIL), and direct bilirubin (DBIL). The Tukey method was used to eliminate outliers. Reference intervals were established by the nonparametric method.ResultsA total of 23,597 healthy individuals were enrolled in the study. From all parameters AST, ALT, TP and ALB required no gender partition, while ALT, GGT, TP, ALB and DBIL required different partitions for age. Activities and concentrations of ALT, ALB, and TP showed a downward trend in the elderly aged 60-89. In contrast, DBIL showed a gradual upward trend.ConclusionThe RIs for liver function tests among healthy elderly population were different from those among young population in China. There were apparent gender and age differences in the RIs of liver function for elderly and significant differences compared with national standards and RIs in other countries. Therefore, it is necessary to establish gender- and age-specific RIs for serum liver function tests among the elderly population.

CLSI Guided Reference Interval Limits for Cancer Biomarkers for Adults and Geriatrics

Reference interval limits for cancer biomarkers in geriatrics are rare because priority is given to the development of reference interval limits for those in the age range of 18–60 years, which are normally used for clinical trials study. The aim of this study was therefore to develop gender and age-specific reference interval limits for cancer markers CA19-9, CEA, CA 15-3, CA 125, and PSA for adults and geriatrics in Taita-Taveta County, Kenya, using the CLSI CA28-A3 guideline. This prospective cross-sectional study involved 244 healthy referents, including 124 females and 120 males of ages 50–95, between May 2015 and December 2017 at the Department of Clinical Chemistry of Moi Subcounty Hospital, Voi, Kenya. Serum CA 19-9, CEA, CA 15-3, CA 125, and PSA of the 244 referents were measured using a well-calibrated, quality controlled Clinical Chemistry AutoAnalyzer. Gender differences in the measured values of the biomarkers were assessed using the Mann-Whitney U test, while age differences were assessed using the Kruskal-Wallis H test followed by the Mann-Whitney U test with an adjusted significant ρ-value of less than 0.0167. Reference interval limits for the measured cancer biomarkers were expressed in terms of medians and ranged between 2.5 and 97.5 percentiles. The established 95% reference interval limits were: 0-58 U/mL males and 0-42.8 U/mL females for CA 19–9, 0–7 ng/mL for CEA, 0-56.9 U/mL for CA 15–3, 0–25 ng/mL for CA 125, and 0–6.8 ng/mL for PSA. Gender-related biomarker values were developed for CA 19-9 adults and geriatrics (60–70 years), CEA for geriatrics (60–70 years), and CA 15-3 for adults. Age-related biomarker values were developed for CA 19–9 males and not for females. In conclusion, gender-related 95% reference interval limits were developed for CA 19-9, CEA, CA 15-3, CA 125, and PSA, and age-related 95% reference interval limits were established for CA 19-9. CA 19-9 decreased from adulthood to the early elderly and increased in the more elderly population. These developed reference interval limits for these biomarkers, which differed from those reported in previous literature, could be adopted for use in Taita-Taveta County, Kenya, for better medical care. Doi: 10.28991/SciMedJ-2022-04-02-04 Full Text: PDF

Steroid profile in dried blood spots by liquid chromatography tandem mass spectrometry: Application to newborn screening for congenital adrenal hyperplasia in China

BackgroundNewborn screening for congenital adrenal hyperplasia (CAH) using 17-hydroxyprogesterone dissociation-enhanced, lanthanide fluorescence immunoassay (DELFIA) generates a large number of false-positive results. The present study aimed to improve the sensitivity of the CAH neonatal screening by including second-tier steroid profiling in dried blood spots (DBS) using liquid chromatography tandem mass spectrometry (LC-MS/MS). MethodsWe developed and validated a LC-MS/MS method for simultaneous determination of six steroids in DBS, including androstenedione, testosterone, 17-hydroxyprogesterone, 11-deoxycortisol, 21-deoxycortisol, and cortisol. Two 5-mm blood spots were eluted by internal standard working solution. We analyzed 1170 DBS samples from neonates to determine gestational age-specific reference intervals. In order to test the specificity of the second-tier method, we analyzed 707 cards with a positive screening by DELFIA. ResultsValues of intra- and inter-day precision coefficients of variance and accuracy were 2.0%–13.3% and 85.8%–114.5%, respectively. Recovery ranged from 85.0% to 106.9%. The lower limit of quantification was 0.5 ng/mL for 21-deoxycortisol, 0.25 ng/mL for 17-hydroxyprogesterone and cortisol, and 0.1 ng/mL for testosterone, androstenedione, and 11-deoxycortisol. In addition, the linearity range was 0.25–50 ng/mL (R2 > 0.99). According to the 17-hydroxyprogesterone levels and ratios of (androstenedione + 17-hydroxyprogesterone)/cortisol in the 707 positive screening samples, 77 neonates should receive recall visit. The number of false-positive results reduced by 89.1%. Totally, 18 newborns were diagnosed with 21-hydroxylase deficiency, one with P450 oxidoreductase deficiency and one with 11β-hydroxylase deficiency. With two-tier screening, the positive predictive value increased to 26.0%. ConclusionsThe second-tier steroid profiling by LC-MS/MS reduced the false-positive rate and improved the positive predictive value of CAH screening. We suggest applying this steroid profiling assay as a second-tier test for CAH screening in China.

Age and sex specific reference intervals of 13 hematological analytes in Chinese children and adolescents aged from 28days up to 20years: the PRINCE study.

Pediatric Reference Intervals in China (PRINCE) is a nationwide initiative that aims to establish and validate harmonized reference intervals (RIs) for Chinese children and adolescents, in which 15,150 healthy volunteers aged up to 20years were recruited from 11 centers to establish RIs and 7,557 children and adolescents were enrolled from 21 centers to validate RIs. The complete blood cell counts (CBC) of venous whole blood were measured by hematology analyzers through Sysmex systems in different centers. Age- and sex-specific RIs were calculated according to the guidelines. Unlike adults with certain levels of analyte concentrations, hematological parameters of children changed through growth and development. Red blood cell counts, hemoglobin, and hematocrit increased with age, and revealed higher concentrations in boys than girls after puberty. White blood cell counts and platelet counts showed significant higher levels than adults before 2years of age, and then gradually decreased without distinct sex differences. In addition, lymphocyte counts decreased with age while neutrophil counts showed an opposite trend. The lower and upper limits of pediatric RIs of CBC were different from those of adults. The validation of RIs indicated that the PRINCE study provided a version of RIs suitable for most of regions in China. This first harmonized pediatric RIs of CBC across China provided a robust database to understand the dynamic changes of hematologic parameters from birth to adolescence, and will contribute to clinical diagnosis and prognosis evaluation for pediatric patients as well.

Hematological Parameters and Indices Reference Interval in Pediatric Egyptian Population; A Single Institution Experience

OBJECTIVE: Differentiating a health from a non-health state requires meticulous knowledge of the reference interval (RI). Over the past years, numerous working groups generated ethnic, age, and gender tailored RI in all laboratory tests. The paucity of regional studies covering the normal hemogram values resulted in the adoption of the western population RI which is influenced by ethnic and geographical differences. AIM: The current study, aimed at generating the Egyptian pediatric group hemogram RI. SUBJECTS AND METHODS: At Abu-Rish Japanese hospital, Cairo University Specialized Pediatric Hospital, the study included 1099 Egyptian surgical patients, of both sexes, with an age range between 1-month and 144 months. The electronic peripheral blood count test results archived in the laboratory information system were collected from January 2006 to December 2017 followed by a non-parametrical comparative study to compute the consecutive age groups for generation of continuous indirect RI (2.5th and 97.5th percentiles). RESULTS: The age clusters, 2–5 months, 6–11 months 12–23 months, 24–59 months, and 60–144 months, were created based on hemoglobin (Hb), Red blood cells count, and platelet count data. CONCLUSION: Previously published pediatric hemogram, Western and African-based, RIs show great variation. The comparative study of Hb between each month of life created different consecutive age groups than those adopted by Western countries and other African countries. The Hb results within each group showed substantial differences, between the RI of the western countries and those of Egyptian subjects specifically a lower limit of anemia diagnosis as well as a lower limit of leucopenia diagnosis. The age-specific RI we propose would change the threshold for anemia, and leucopenia diagnosis. The results might justify the use of national RI, after its validation, instead of the international ones.

Reference Ranges of Selenium in Plasma and Whole Blood for Child-Bearing-Aged Women in China.

Selenium (Se) is a “dual-surface” element. Both Se-deficiency and Se-overload have bad effects on humans. The amount of Se in the blood is a good indicator of Se intake, and there are considerable differences in the reference ranges among different regions and populations. The purpose of this study was to establish the age-specific reference interval of blood Se in healthy child-bearing-aged women in China. A total of 187 healthy women aged 18–45 years old were enrolled with strict inclusion criteria from the China Adult Chronic Disease and Nutrition Surveillance (2015 CACDNS) database to establish the reference interval of Se. Plasma and whole-blood Se were detected by inductively coupled plasma mass spectrometry (ICP-MS). The reference range (RR) estimated as P2.5–P97.5 percentiles (geometric mean) was 73.81–140.75 (100.94) μg/L and P2.5–P97.5 percentiles (median) 81.06–164.75 (121.05) μg/L for plasma and whole-blood Se, respectively. The proposed RR of plasma Se in this study was used to evaluate the Se nutritional status of a representative sample of 1950 women of child-bearing age who were randomly selected from 2015 CACDNS. The proportion of Se level lower than P2.5 cut-off value was 24.05%, and there were 5.08% child-bearing-aged women with plasma Se higher than the upper limit of RR. Women in the western and rural areas tend to have lower Se levels.

Elective ovariohysterectomy or castration can proceed in shelter dogs despite mild to moderate presurgical leukocytosis.

To determine whether shelter dogs presenting for elective ovariohysterectomy or castration have leukocytosis, whether leukocytes are associated with age and infection, and whether leukocytosis precludes progression to surgery. 138 dogs (from 13 regional shelters) presented for ovariohysterectomy or castration between October 7 and December 6, 2019. For this prospective study, each dog underwent presurgical physical examination, CBC, and tests for Dirofilaria immitis antigen and Anaplasma phagocytophilum, Borrelia burgdorferi, and Ehrlichia canis antibodies, with additional tests performed as needed. Dogs were aged by dentition as juvenile (< 3 or ≥ 3 to ≤ 6 months) or adult (> 6 months). Leukogram results were compared across age groups with recognized infections and parasitism and with dogs' progression to surgery. There were 34 dogs < 3 months old, 22 dogs ≥ 3 to ≤ 6 months old, and 82 > 6 months old. Sixty-three of 138 (45.6%) dogs had leukocytosis (median, 16,500 cells/µL; range, 13,700 to 28,300 cells/µL). Dogs < 3 months of age had higher median leukocyte and lymphocyte counts (14,550 cells/µL and 3,700 cells/µL, respectively) than dogs > 6 months of age (12,500 cells/µL and 2,400 cells/µL, respectively). Only 1 dog had a stress leukogram. Forty-seven dogs had recognized infection, but there was no association with leukocytosis. Surgery proceeded successfully for all dogs with leukocytosis. Mild to moderate leukocytosis is common before elective surgery in shelter dogs, but surgery can proceed safely. A CBC should be reserved for ill-appearing dogs rather than as a screening test, and age-specific reference intervals should be considered.

Establishment of reference intervals of homocysteine, cysteine, and methionine in apparently healthy Chinese adults

Background It has been widely reported that the key biomarkers of homocysteine metabolic pathways have emerged as markers or independent risk factors for cardiovascular disease and many other diseases. To improve the accuracy of evaluation in China, we establish the reference intervals of serum homocysteine (Hcy), cysteine (Cys), and methionine (Met) in apparently healthy Chinese adults. Methods We examined 1553 subjects aged ≥20 years who underwent Hcy metabolic pathway tests, in the Chaoyang Central Hospital between January 2019 and December 2020. The serum Hcy, Cys, and Met levels were simultaneously determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Multiple regression analysis was performed to identify sources of variation. A nonparametric method was used to establish the reference intervals. Results Gender differences were observed in Hcy and Met, with higher levels in males. Reference intervals for males were 6.09–17.00 μmol/L (Hcy) and 19.31–33.68 μmol/L (Met); conversely, the reference intervals for females were 4.61–14.61 μmol/L (Hcy) and 16.16–30.35 μmol/L (Met). The serum Cys reference intervals were seen to be gender-independent, but age-dependent reference intervals were needed; those for Cys were 188.85–334.27 μmol/L, 200.48–340.66 μmol/L, and 216.03–349.67 μmol/L in <40, 40–50, and ≥50 years, respectively. Conclusions By this study, the gender- or age-specific reference intervals of Hcy, Cys, and Met that were matched with the Chinese population were established, providing valuable references for clinical work and laboratory researches.

Pediatric ionized calcium reference intervals from archived radiometer data

BackgroundMeasurement of ionized calcium (iCa) reflects bioavailable calcium and has significant utility in children. However, robust pediatric iCa reference intervals (RI) have not been well-established. In this study, we retrospectively calculated RI for iCa in a pediatric population by accessing archived data acquired on Radiometer instruments and applying stringent exclusion criteria. MethodsData saved on 4 Radiometer ABL800 FLEX blood gas analyzers were queried. Exclusion criteria were applied based on information available from these instruments. iCa results were plotted and inflection points were visually identified. Following outlier removal and partition verification, age-specific RI were calculated using a nonparametric rank order approach from > 5,000 individuals. Finally, the stringency of the exclusion criteria was assessed by calculating RI from additional results in the dataset and comparing to existing in-house ranges. ResultsSix age-specific iCa partitions were established from 0 to 19 years. Relative to adults, wider ranges for the central 95th percentile were observed early in life that progressively narrowed with increasing age and approached adult concentrations by 2.5 years. Analysis of concurrent data for sodium and creatinine in the dataset suggest the applied exclusion criteria reduced the likelihood of including results from acutely-ill children. ConclusionsNormal concentrations of iCa in children are more variable than adults. Observed differences may reflect the transition from maternally supplied calcium to nutritional sources, the maturation of calcium homeostatic mechanisms, and/or the need for calcium for growth/development. This study also demonstrates the feasibility and advantages of using data archived on Radiometer analyzers to establish pediatric RI. This approach enables rapid, cost-effective evaluation of large datasets and may be a feasible option when prospective or detailed retrospective analyses are not possible.

Establishment of Age-Specific Whole Blood Biochemistry and Gas Reference Intervals in Broiler Chickens using the i-STAT and the Vetscan VS2 Portable Analyzers.

Whole blood biochemistry and blood gas analysis are uncommonly used in poultry, but their use could improve the diagnosis of certain diseases or aid in monitoring flock health. To create preliminary reference intervals for selected blood analytes in broilers using the i-STAT and Vetscan VS2 (VS2) portable analyzers, we tested broilers at 7, 21, and 35 days of age. A total of 134 venous blood samples from healthy chickens of two different flocks were analyzed. There were significant age-related increases in concentration for glucose, hematocrit, ionized calcium, sodium, and carbon dioxide partial pressure on the i-STAT and for aspartate aminotransferase, creatine kinase, total calcium, phosphorus, and total protein on the VS2. Conversely, significant decreases in concentration were observed for pH, oxygen partial pressure, oxygen saturation on the i-STAT and for uric acid and albumin on the VS2. Additionally, significant differences were found on some blood parameters among the two flocks. Extremely high CK values were found on broilers after 21 days of age, indicating a possible degree of muscle injury during the grow-out. Preliminary reference intervals for all the analytes at each of the age groups were obtained. This study's data provide a starting point for the interpretation of blood analysis in broiler chickens at different ages and offer a new approach to investigate certain metabolic diseases that affect commercial poultry.

Improving diagnostic accuracy in pregnancy with individualised, gestational age-specific reference intervals

Background and aimsInvestigations in pregnancy should be interpreted using pregnancy-specific reference intervals (RIs). However, because of the progressive nature of pregnancy, even pregnancy-specific RIs may not be equally representative at different gestations. We proposed that gestational age-specific RIs may increase diagnostic accuracy over those with fixed limits. Materials and methodsThe trajectory of platelets was mapped in 32,778 pregnant women, using 116,798 results. Then we evaluated the accuracy with which a low measurement in early pregnancy (<3rd centile) predicted thrombocytopaenia at term, compared to the existing limit (<150 × 109/L). ResultsPlatelets fell by 14.8% between 8 and 40 weeks. Platelets below the 3rd centile before 20 weeks predicted thrombocytopaenia at term (<100 × 109/L) with a significantly greater degree of accuracy than a fixed limit (AUC 0.86 vs. 0.76, p = 0.004). ConclusionPregnancy-specific RIs can be defined using routinely collected hospital data, and the abundance of such freely available data enables a detailed investigation of temporal changes throughout gestation. Individualised RIs offer improved accuracy profiles, over and above those already derived specifically from pregnant populations. Clinicians should consider how this may be used to improve diagnostic accuracy for biomarkers used in current clinical practice, and those yet to be defined.

Complex biological patterns of soluble cytokines and CD163 in childhood necessitating age-specific reference intervals for evidence-based clinical interpretation

BackgroundCytokine measurements to support clinical laboratory and research investigations have become increasingly common in pediatrics. However, there is a paucity of accurate pediatric reference intervals (RIs) essential to the interpretation of cytokine results. To address this gap, here, we establish age- and sex-specific pediatric reference values for clinically relevant inflammatory markers including CD163, and the cytokines IL-1β, IL-6, IL-10, IL-18, TNF-α, IFN-γ, and CXCL-9. MethodsHealthy children and adolescents (n = 311, 1–19 years) were recruited as part of the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) study. Multi-analyte measurements in plasma and analytical performance verification were conducted on the ProteinSimple® Ella™ automated immunoassay platform (Bio-Techne, MN, USA). Age- and sex-specific RIs were calculated based on Clinical and Laboratory Standards Institute guidelines. Additionally, 75th and 95th percentile cut-offs were determined. ResultsThree types of reference value distributions were observed: (a) consistent levels throughout age and sex: IL-6, and IFN-γ, (b) gradual decline in concentration with age: CD163, TNF-α, CXCL-9, and IL-10, (c) significantly higher concentrations during ages 4–14 years than earlier and later ages: IL-1β and IL-18. Reference values for CXCL-9, IL-10, and TNF-α under 8 years of age differed significantly from older children. CD163, IL-18 and IL-1β required three age partitions. CD163 demonstrated significant sex differences in ages 8–13 years. ConclusionThe circulating profile of cytokines in children is complex and can vary by age and sex. This necessitates careful interpretation of test results based on age and/or sex specific RIs facilitating more accurate clinical decision making.