Separate Reference Intervals Research Articles

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.

Measuring the Level of Agreement for Lactate Measurements in Hispaniolan Amazon Parrots (Amazona ventralis) Among 2 Point-of-Care Analyzers and a Benchtop Analyzer.

Lactate is an important biochemistry analyte used in human and veterinary medicine to assess tissue perfusion and can be used as a prognostic indicator for certain disease conditions. Whereas lactate is commonly measured using "patient-side" handheld meters, these meters have not been validated for companion avian species. The purpose of this study was to measure the level of agreement between 2 commercially available point-of-care lactate meters and a laboratory benchtop blood analyzer in Hispaniolan Amazon parrots (Amazona ventralis). Blood samples were collected from 20 adult parrots at Louisiana State University by drawing 1.5 mL of blood from the right jugular vein. One drop of whole blood was used for the Lactate Plus analyzer and the remainder of the sample transferred into a lithium heparin microtainer. From the blood in the microtainer, 0.2 mL whole blood was analyzed using the epoc Blood Analysis System, and the remaining sample was centrifuged to obtain plasma that was immediately frozen at -80°C (-112°F) and submitted to the Texas A&M University Clinical Pathology Laboratory for analysis on the VITROS 4500 benchtop analyzer. Bland-Altman agreement plots and Passing-Bablok regression were used to measure the level of agreement between the methods. There was poor agreement between all 3 methods with mean percentage differences in lactate concentrations ≥22% (epoc and Lactate Plus: 33.6% [95% CI: 27-40]; epoc and VITROS 4500: 55% [95% CI:52-58]; VITROS 4500 and Lactate Plus: 22% [95% CI:16-28]). Based on these results, the point-of-care meters tested in this study are not interchangeable, and separate reference intervals were calculated for each method. Blood lactate concentrations may have more utility in tracing lactate trends over time in an individual rather than being able to utilize this information at 1 time point for disease diagnosis and prognosis.

Establishment of CA19-9 reference intervals in an apparently healthy adult population in Singapore.

CA19-9 is elevated in pancreatic cancer and other malignancies, and commonly used in clinical practice. Unfortunately, CA19-9 immunoassays are not harmonized, and reference intervals may differ between assays. The aim of this study was to establish the reference interval of the ADVIA Centaur/Atellica IM CA19-9 assay in an apparently healthy Singapore adult population. This is a retrospective cross-sectional study. De-identified data from Health Screening participants were extracted from our database. Subjects with biochemical results suggesting anaemia, diabetes mellitus, viral hepatitis or abnormal liver, and renal and tumour markers were excluded. Outlier and subclass analyses by age and sex were performed. CA19-9 reference limits and 90% confidence intervals were then determined for candidate subclasses. Data from 12,174 subjects (5846 males and 6328 females) were available after exclusion criteria were applied. CA19-9 results did not follow a normal distribution and were higher in females compared to males (P < .001). Although CA19-9 means were statistically different between certain age groups, the evaluable 99th percentile reference limits were not statistically different. The overall 99th percentile reference limits for the Centaur/Atellica CA19-9 assay was 37 U/mL for males 21-80years, and 60U/mL for females 21-80years. Our results suggest that separate CA19-9 reference intervals should be applied for males and females.

Evaluating Different Methods for Determining Erythrocyte Sedimentation Rate in Free-Living Blanding's Turtles (Emydoidea blandingii).

Characterizing host factors affecting individual health can be important in the conservation of many chelonians, including the Blanding's turtle (Emydoidea blandingii). However, many routine clinical pathology tests do not reliably detect differences in health status in reptiles. The erythrocyte sedimentation rate (ESR) has been shown to characterize inflammation in many species, including tortoises, and may be useful in assessing Blanding's turtles. The purpose of our study was to evaluate two methods of ESR measurement in free-ranging Blanding's turtles. Sixty Blanding's turtles captured at two sites in Illinois received a complete physical examination, and blood was collected for determination of packed cell volume, total solids, and ESR with both microhematocrit tubes and commercial kits (Winpette). Method agreement was assessed with Passing-Bablok regression. Associations between ESR and demographic, environmental, and health factors were determined by linear regression. The microhematocrit tube method proportionately overestimated ESR compared with the Winpette. With the use of both measurement methods, ESR was significantly different between study sites, higher in adult Blanding's turtles, and higher in females that were gravid compared with those that were not. ESR was also negatively associated with packed cell volume. ESR values in Blanding's turtles are comparable to other reptiles, and although microhematocrit tube and Winpette results are not interchangeable, their associations with biological predictors are similar, and either method has the potential to be used with separate reference intervals to assess turtles for inflammatory conditions.

Rectangular tolerance regions and multivariate normal reference regions in laboratory medicine.

Reference intervals are widely used in the interpretation of results of biochemical and physiological tests of patients. When there are multiple biochemical analytes measured from each subject, a multivariate reference region is needed. Because of their greater specificity against false positives, such reference regions are more desirable than separate univariate reference intervals that disregard the cross-correlations between variables. Traditionally, under multivariate normality, reference regions have been constructed as ellipsoidal regions. This approach suffers from a major drawback: it cannot detect component-wise extreme observations. In the present work, procedures are developed to construct rectangular reference regions in the multivariate normal setup. The construction is based on the criteria for tolerance intervals. The problems addressed include the computation of a rectangular tolerance region and simultaneous tolerance intervals. Also addressed is the computation of mixed reference intervals that include both two-sided and one-sided limits, simultaneously. A parametric bootstrap approach is used in the computations, and the accuracy of the proposed methodology is assessed using estimated coverage probabilities. The problem of sample size determination is also addressed, and the results are illustrated using examples that call for the computation of referenceregions.

Rectangular multivariate normal prediction regions for setting reference regions in laboratory medicine

ABSTRACT Reference intervals are among the most widely used medical decision-making tools and are invaluable in the interpretation of laboratory results of patients. Moreover, when multiple biochemical analytes are measured on each patient, a multivariate reference region (MRR) is needed. Such regions are more desirable than separate univariate reference intervals since the latter disregard the cross-correlations among variables. Traditionally, assuming multivariate normality, MRRs have been constructed as ellipsoidal regions, which cannot detect componentwise extreme values. Consequently, MRRs are rarely used in actual practice. In order to address the above drawback of ellipsoidal reference regions, we propose a procedure to construct rectangular MRRs under multivariate normality. The rectangular MRR is computed using a prediction region criterion. However, since the population correlations are unknown, a parametric bootstrap approach is employed for computing the required prediction factor. Also addressed in this study is the computation of mixed reference intervals, which include both two-sided and one-sided prediction limits, simultaneously. Numerical results show that the parametric bootstrap procedure is quite accurate, with estimated coverage probabilities very close to the nominal level. Moreover, the expected volumes of the proposed rectangular regions are substantially smaller than the expected volumes obtained from Bonferroni simultaneous prediction intervals. We also explore the computation of covariate-dependent MRRs in a multivariate regression setting. Finally, we discuss real-life applications of the proposed methods, including the computation of reference ranges for the assessment of kidney function and for components of the insulin-like growth factor system in adults.

Plasma von Willebrand Factor Antigen Levels and Its Relation with ABO Blood Group, Age and Sex

Background: The ABO blood antigens may influence the levels of vWF: Ag and put individuals at risk of coagulopathies. This study assessed the plasma vWF: Ag and its relation with ABO blood antigens among healthy adults in northern Ghana. Methods: This cross-sectional study recruited 84 blood donors, aged 18–50 years, at Tamale Teaching Hospital. Blood groups were determined using the standard tube method, and a complete blood count was measured with an automated haematology analyzer. Sandwich ELISA was used to assess plasma vWF: Ag levels. The data obtained were analyzed using SPSS version 22. Results: The frequencies of O, A, B, and AB blood groups were 34 (40.5%), 25 (29.8%), 20 (23.8%), and 5 (6.0%), respectively. vWF: Ag levels were higher among the non-O than group O individuals (p = 0.008). Plasma vWF: Ag levels were lower in group O compared to AB (p = 0.015) and A (p = 0.013) individuals. Males had higher vWF: Ag levels than females (p = 0.002). A moderately positive correlation was observed between age and vWF levels (r = 0.497, p&lt;0.001). Blood group O participants had lower absolute neutrophil counts (p = 0.039), but higher RDW-SD (p = 0.045). Conclusion: The predominant blood group was O, followed by other groups in the order: O&gt;A&gt;B&gt;AB. Plasma vWF: Ag levels were higher in non-group O compared with group O individuals. Males had higher vWF: Ag levels, and a positive correlation between age and vWF: Ag was observed. Again, blood group O participants had lower neutrophil counts, but higher RDW-SD. The relationship between ABO blood phenotypes and plasma vWF: Ag should be considered in clinical practice. The establishment of separate reference intervals of vWF: Ag for the various phenotypes of ABO is recommended. Also, the study recommends further multicenter studies to assess the link between ABO phenotypes and all the endothelial cell parameters. Doi: 10.28991/SciMedJ-2022-04-02-02 Full Text: PDF

Biochemical reference intervals in broiler chickens according to age and strain

Abstract. The objective of the research was to study the physiological pattern of biochemical variables and to obtain reference intervals for young (less than 1 month) and adult (more than 1 month) broiler chickens of 2 strains. From the jugular vein, blood for analysis was collected, separated, and then immediately analyzed. The influence of age was significant for the majority of the investigated variables in the 2 groups. In Isa15 strain, a significant age-related decrease in plasma uric acid, glucose, cholesterol, triglycerides, phosphorus, potassium and iron was established. Also, a significant age-related increase in plasma calcium and ASAT was obtained in the same broiler strain. In Arbor Acres Plus strain, a significant age-related decrease in plasma glucose, cholesterol, triglycerides and phosphorus was observed. A significant age-related increase in plasma total protein, calcium and ASAT has also been reported in this broiler strain. A significant difference between the two strains was reported for plasma uric acid, glucose, cholesterol, phosphorus, magnesium and iron (p&lt;0.05). For most estimated parameters in the 2 strains, calculation of separate reference intervals for young and adult animals was appropriate. Except for potassium in young Isa15 strain, and phosphorus in young Arbor Acres Plus strain, all variables did not follow a normal distribution. Reference intervals are presented for both ages using non-parametric or robust method. 90% confidence intervals for both groups were calculated non-parametrically, or by the bootstraping method. The established reference intervals will be a useful guide for interpreting plasma biochemical variables in different strains of broiler chickens raised in Algeria, and reared in a mild Mediterranean climate.

Comparison of selected serum biochemistry measurements between the Nova Prime Plus VET, Nova pHOx Ultra, and Beckman Coulter AU680 analyzers in dogs.

Blood gas chemistry analyzers typically produce results faster and use smaller sample volumes than reference chemistry analyzers. However, results may not be comparable between blood gas chemistry analyzers and reference chemistry analyzers or between different models of blood gas chemistry analyzers. This could suggest the use of separate reference intervals and, thus, has implications when making clinical decisions. We aimed to perform method comparison studies to evaluate selected canine serum biochemical values obtained using the Nova Stat Profile Prime Plus VET (Prime Plus VET), Stat Profile Nova pHOx Ultra (Ultra), and Beckman Coulter AU680 (Beckman) analyzers. We hypothesized that the three analyzers would be identical within inherent imprecision. Jugular venous blood samples were collected from 103 endurance-trained sled dogs, and serum was harvested and stored for analysis. Results for serum chloride, potassium, sodium, creatinine, and urea nitrogen concentrations obtained from the Prime Plus VET and Ultra analyzers were compared with results from the Beckman analyzer, which was considered to be a reference method. Results for serum chloride, potassium, sodium, creatinine, urea nitrogen, and L-lactate concentrations obtained from the Prime Plus VET and Ultra analyzers were compared. Passing-Bablok regression and Bland-Altman plots were used for method comparison. Significant (P<0.05) constant or proportional bias was found for many analytes for all three method comparison studies. Due to the presence of statistically significant differences between all three analyzers that may be clinically relevant, it is recommended that reference intervals be created for new blood gas analyzers, even when similar methodologies are used.

Establishing reference intervals of 20 biochemical markers for children in Southwestern Fujian, China based on the UniCel DxC 800 system

To date, China has no industry standard for reference intervals of paediatric blood biochemical markers. This study aimed to evaluate changes in biochemical markers in the venous blood of healthy children aged 29 days to 12 years, derived from the UniCel DxC 800 system, and establish appropriate reference intervals. We analysed venous blood from 1980 healthy children for 20 biochemical markers. Reference intervals were established according to the Clinical and Laboratory Standards Institute C28-A3c guideline and compared with those of adults in China. All markers except for sodium and chlorine required partitioning by age, but not by sex. The reference intervals of total protein, albumin, globulin, carbon dioxide, urea nitrogen, creatinine and uric acid consistently increased with age in children, but were always lower than those of adults. Children aged 29 days to 12 years had a single combined RI for sodium and chloride, respectively; although the reference intervals in children were similar to those of adults, their upper limits were lower. The reference intervals of direct bilirubin, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, potassium, calcium, magnesium, and phosphorus continued to decline with age. The reference intervals of total bilirubin, indirect bilirubin, and gamma-glutamyl transpeptidase initially declined followed by a slight rebound. While establishing reference intervals, most markers required partitioning by age (aged 29 days to 12 years); the partitioning scheme differed for each marker, and paediatric reference intervals differed from those for adults. It is therefore necessary to establish separate paediatric reference intervals.

Establishment of sex-specific reference intervals for automated haematology analyser-delivered research parameters in healthy Korean adults: a retrospective database review

ObjectivesAutomated haematology analysers measure various parameters of relevance to clinical research along with routine complete blood count (CBC)-related components. We aimed to establish ethnicity-specific and sex-specific reference intervals for 26...

Erythrocyte sedimentation rate and hemoglobin-binding protein in free-living box turtles (Terrapene spp.)

The acute phase response is a highly conserved reaction to infection, inflammation, trauma, stress, and neoplasia. Acute phase assays are useful for wildlife health assessment, however, they are infrequently utilized in reptiles. This study evaluated erythrocyte sedimentation rate (ESR) in eastern (Terrapene carolina carolina) and ornate box turtles (Terrapene ornata ornata) and hemoglobin-binding protein (HBP) in T. ornata. Erythrocyte sedimentation rate in 90 T. carolina and 105 T. ornata was negatively associated with packed cell volume and was greater in unhealthy turtles (p < 0.05). Female T. ornata had higher ESR values than males (p < 0.05). Measurement of ESR with a microhematocrit tube proportionally overestimated values from a commercial kit (Winpette), though both methods may retain utility with separate reference intervals. Hemoglobin-binding protein concentration in 184 T. ornata was significantly increased in adults and unhealthy turtles (p < 0.05). Erythrocyte sedimentation rate values were similar between seasons and populations, and HBP values were consistent between years, indicating that these analytes may have more stable baseline values than traditional health metrics in reptiles. This study demonstrates that ESR and HBP are promising diagnostics for health assessment in wild box turtles. Incorporating these tests into wild herptile health assessment protocols may support conservation efforts and improve ecosystem health monitoring.

Sex-divided reference intervals for mean platelet volume, platelet large cell ratio and plateletcrit using the Sysmex XN-10 automated haematology analyzer in a UK population

BackgroundThis study aimed to define the sex-divided reference intervals for platelet indices (mean platelet volume (MPV), platelet distribution width (PDW), platelet large cell ratio (P-LCR) and plateletcrit (PCT)) on the Sysmex XN-10. MethodsA total of 2376 samples were assayed for full blood count on the Sysmex XN-10 haematology analyzer. After removing the outliers, reference intervals were calculated using the mean±2SD. The P value 0.05 was adopted to denote statistical significance. ResultsThere was a statistical significance (α=0.05) between sex-divided reference intervals for MPV (p=0.007), P-LCR (p=0.015) and PCT (p<0.001), thus separate reference intervals were calculated for these indices, with orientation to the sex-divisions as follows: MPV, 9.1–13.0fL [males] and 9.2–12.8fL [females]; P-LCR, 17.6–47.0% [males] and 17.8–47.8% [females]; and PCT, 0.16–0.35% [males] and 0.18–0.37% [females]. No significance was found between sex-divided reference intervals for the PDW (p=0.838), therefore a reference interval for total individuals was calculated for this platelet measurement as 9.3–17.3fL. ConclusionThis study showed comparable reference intervals, using the Sysmex XN-10, with the previous literature. It determined the need to define sex-specific reference intervals for the MPV, P-LCR and PCT, but not for the PDW. These reference intervals will allow for low and high values to be facilitated in order to do further research and guide platelet disorder management.

A Comparison of Complete Blood Count Reference Intervals in Healthy Elderly Versus Younger Korean Adults: A Large Population Study

Background: The use of laboratory reference intervals based on younger populations is of questionable validity in older populations. We established reference intervals for 16 complete blood count (CBC) parameters in healthy elderly Koreans aged ≥60 years and compared them to those of individuals aged 20-59 years.Methods: Among 64,532 individuals (39,609 men and 24,923 women) aged ≥20 years who underwent medical check-ups, 8,151 healthy subjects (12.6%, 5,270 men and 2,881 women, including 675 and 511, respectively, who were ≥60 years of age) were enrolled based on stringent criteria including laboratory, imaging, and endoscopy results; previous medical history; and medication history. CBC parameters were measured using an Advia2120i instrument. The difference between 2 age groups in subjects of each sex was compared using the Mann-Whitney U-test. P-values <0.05 were considered statistically significant. The reference intervals for measured CBC parameters were established according to a nonparametric method based on the CLSI EP28A-3C in each subgroup. The 90% confidence intervals for the upper and lower limits of each reference interval were calculated; the Reed method was used to remove extreme outliers. The Harris and Boyd method was used to determine the necessity of separating the reference intervals for different age groups within each sex group. To identify reference intervals in different age groups in individuals aged 60 years and over, such individuals of each sex were subdivided into 5 age subgroups with 5-year age interval: since the sizes of 4 of these subgroups were not sufficiently large, we used the Robust method.Results: A statistical difference in the medians of the following parameters were observed between the <60- and ≥60-year age groups: RBC, Hb, hematocrit (Hct), basophils, and platelets in men aged <60 years were higher than those in men aged ≥60 years; furthermore, MCV, MCH, and RDW in men aged ≥60 years were higher than those in men aged <60 years. Neutrophils in women aged <60 years were higher than in those aged ≥60 years. Hb, Hct, MCV, MCH, MCHC, lymphocytes, and basophils in women aged ≥60 years were higher than in those aged <60 years. Separate reference intervals were required only for RDW and MCH in women ≥60 from those < 60 years of age. Men aged ≥60 years versus those <60 years did not require separate reference intervals for any of the 16 measured parameters. In subjects aged ≥60 years, RBC, Hb, Hct, MCV, MCH, MCHC, RDW, WBC, neutrophils, monocytes, eosinophils, MPV, and PDW were higher in men than in women, while the opposite was true for lymphocytes and platelets. Partitioning of reference intervals by sex was required for RBC, Hb, Hct, MCH, monocytes, and eosinophils. In men, median values and the lower limits of the reference intervals for RBC, Hb, and Hct tended to decrease with advancing age. The upper and lower limits of reference intervals for WBC, neutrophils, lymphocytes, and MPV also showed increasing and decreasing tendencies, respectively, widening the reference intervals as the subjects aged (except in the 70-74-year-old group for men). Among women, the lower limits of the reference intervals for RBC, Hb, and Hct showed a tendency to decrease with increasing age for those >70 years of age; however, the median values did not show such a tendency. The reference interval for PDW narrowed as women aged. Separate reference intervals were required among men for MCH and eosinophils in the 70-74-year group, and for basophils in the 65-69-year group. Among women, separate reference intervals were required for MCV in the 65-69-year group; for MCH in the 60-64, 65-69, and ≥75-years groups; and for RDW in all the 4 elderly age subgroups.Conclusion: Healthy elderly Koreans can use the same reference intervals as younger populations. Thus, abnormal CBC results may not necessarily be attributable to physiologic changes but possible underlying diseases that should be investigated. DisclosuresNo relevant conflicts of interest to declare.

A comparison of complete blood count reference intervals in healthy elderly vs. younger Korean adults: a large population study.

Background The use of laboratory reference intervals based on younger populations is of questionable validity in older populations. We established reference intervals for 16 complete blood count (CBC) parameters in healthy elderly Koreans aged ≥60 years and compared them to those of individuals aged 20-59 years. Methods Among 64,532 individuals (39,609 men and 24,923 women) aged ≥20 years who underwent medical checkups, 8151 healthy subjects (12.6%, 5270 men and 2881 women, including 675 and 511, respectively, who were ≥60 years of age) were enrolled based on stringent criteria including laboratory, imaging and endoscopy results; previous medical history; and medication history. CBC parameters were measured using an Advia2120i instrument. Results Overall, healthy individuals aged ≥60 years did not require separate reference intervals from those aged <60 years except for red cell distribution width (RDW) and mean corpuscular hemoglobin (MCH) in women. However, subjects aged ≥60 years still required sex-specific reference intervals for red blood cell count, hemoglobin, hematocrit, MCH, monocytes and eosinophils. Separate reference intervals were required for MCH, eosinophils and basophils for certain age subgroups of men aged ≥60 years, and for MCH and RDW in certain age subgroups of women aged ≥60 years, compared to counterparts <60 years of age. Conclusions Healthy elderly Koreans can use the same reference intervals as younger populations. Thus, abnormal CBC results may not necessarily be attributable to physiologic changes but possible underlying diseases that should be investigated.

Determination of the reference values of amino acids and acylcarnitines level in the newborn dry blood spots in Ukraine

Aim. Implementation of neonatal screening of the group of severe inherited disorders of amino acids, fatty and organic acids metabolism in Ukraine involves determination of the biological variation of amino acids and acylcarnitines level in the blood that depends on the gender, geographical origin of the samples and the gestation term of newborn. Methods. The main method of rapid and reliable diagnosis of this group of inherited disorders is determination of amino acids and acylcarnitines level by liquid chromatography tandem mass spectrometry. Results. Reference intervals of amino acids and acylcarnitines concentration in dry blood samples of newborns from different regions of Ukraine haven’t differed. However, it was found necessity to use separate reference intervals of some amino acids and acylcarnitines (citrulline, arginine, methionine, leucine, tyrosine, alanine, histidine, C0, C3, C3DC, C4, C5, C6, C8, C8:1, C10:2, C12, C14:1, C16, C18OH, C18:1OH) for premature and full-term newborns. Also, it was revealed that for male and female newborns it is necessary to use different reference intervals of citrulline, leucine, C8:1, arginine, methionine, C5, C8. Conclusions. In this study it was found that variation of amino acids and acylcarnitines concentration in dry blood spots depends on the newborns gestation term and sex. We have proposed a two-stage procedure of biomarkers interpretation for which the values variation in different neonatal groups was detected. Keywords: amino acids and acylcarnitines reference intervals, inherited disorders of amino acids, fatty and organic acids metabolism, newborn screening.

Chinese Pediatric Reference Intervals for Serum Cortisol on IMMULITE 2000.

Clinical interpretation of the test results for cortisol based on continuous reference intervals with appropriate partitions improves pediatric diagnosis; however, these values are available only for Caucasians. To develop the pediatric reference intervals for Chinese population, we examined the serum cortisol levels in 1,143 healthy Chinese children aged 4–18 years (566 boys and 577 girls), using an IMMULITE 2000 Immunoassay System (Siemens Healthcare GmbH). Phlebotomy was performed at 7–9 a.m. for 284 boys and 287 girls and at 1–3 p.m. for the others. They were divided into four age groups according to the Clinical and Laboratory Standards Institute guideline EP28-A3c, with the last group further stratified according to sampling time. Separate reference intervals of 49.6–323.7, 70.9–395.3, and 90.1–448.7 nmol/L were established for children aged 4–8, 9–12, and 13–15 years, respectively. Further, reference intervals of 118.2–464.7 and 71.4–446.7 nmol/L were established for morning and afternoon cortisol levels, respectively, in children aged 16–18 years. Further studies are necessary to transfer and validate these reference intervals in other analytical systems and pediatric populations, and to allow for broader applications.

BRIDGING GAPS BETWEEN ZOO AND WILDLIFE MEDICINE: ESTABLISHING REFERENCE INTERVALS FOR FREE-RANGING AFRICAN LIONS (PANTHERA LEO)

The International Species Information System has set forth an extensive database of reference intervals for zoologic species, allowing veterinarians and game park officials to distinguish normal health parameters from underlying disease processes in captive wildlife. However, several recent studies comparing reference values from captive and free-ranging animals have found significant variation between populations, necessitating the development of separate reference intervals in free-ranging wildlife to aid in the interpretation of health data. Thus, this study characterizes reference intervals for six biochemical analytes, eleven hematologic or immune parameters, and three hormones using samples from 219 free-ranging African lions ( Panthera leo ) captured in Kruger National Park, South Africa. Using the original sample population, exclusion criteria based on physical examination were applied to yield a final reference population of 52 clinically normal lions. Reference intervals were then generated via 90% confidence intervals on log-transformed data using parametric bootstrapping techniques. In addition to the generation of reference intervals, linear mixed-effect models and generalized linear mixed-effect models were used to model associations of each focal parameter with the following independent variables: age, sex, and body condition score. Age and sex were statistically significant drivers for changes in hepatic enzymes, renal values, hematologic parameters, and leptin, a hormone related to body fat stores. Body condition was positively correlated with changes in monocyte counts. Given the large variation in reference values taken from captive versus free-ranging lions, it is our hope that this study will serve as a baseline for future clinical evaluations and biomedical research targeting free-ranging African lions.

A NEED FOR DYNAMIC HEMATOLOGY AND SERUM BIOCHEMISTRY REFERENCE TOOLS: NOVEL USE OF SINE WAVE FUNCTIONS TO PRODUCE SEASONALLY VARYING REFERENCE CURVES IN PLATYPUSES (ORNITHORHYNCHUS ANATINUS).

Seasonal changes in hematology and serum biochemistry results, described by separate reference intervals for different seasons, have been reported in many animals. We developed a novel method to investigate seasonal variation in values and a reference tool (the reference curve) based on sine wave functions that, for suitable variables, represents data more appropriately than a fixed reference interval. We applied these techniques to values observed in blood samples from 126 adult wild platypuses ( Ornithorhynchus anatinus ; 58 females and 68 males). Samples were collected under isoflurane anesthesia from animals captured in the Inglis Catchment in northwest Tasmania. In general, packed cell volume (PCV), red cell count (RCC), and hemoglobin (Hb) values appeared to be lower than those in two studies that previously reported platypus hematology reference intervals. This likely resulted from reduced stress-related splenic contraction or isoflurane-associated splenic sequestration of red blood cells in our study. Reference curves were described for five variables (PCV, RCC, Hb, albumin, and magnesium). We found evidence that this seasonal variation may result from metabolic changes associated with seasonal variations in environmental temperature. These observations suggest that it is important for researchers reporting platypus hematology and serum biochemistry to look for seasonal changes in their data to ensure it is appropriately interpreted.

Gestational age-specific reference intervals for serum thyroid hormone levels in a multi-ethnic population.

Thyroid disorders are common during pregnancy. To date, a limited number of studies have reported differences in serum thyroid hormone concentrations between different ethnic groups. We sought to establish gestational age-specific reference intervals for serum levels of thyroid hormones in a multi-ethnic population and investigate whether separate reference intervals should be used for different ethnic groups. A total of 926 pregnant women from multiple ethnic groups attended four separate study visits spanning the three trimesters. Venous blood samples were taken at 9 to 14 weeks, 18 to 22 weeks, 28 to 32 weeks, and 34 to 39 weeks of gestation. Serum concentrations of thyroid-stimulating hormone (TSH), free thyroxine (T4), free triiodothyronine (T3), total T4, total T3, thyroid peroxidase antibody and thyroglobulin antibody were measured using Abbott Architect immunoassays. A total of 562 women with singleton pregnancies were found to be negative for both thyroid autoantibodies at all four study visits and thus included in the reference sample group for the establishment of reference intervals (2.5th to 97.5th percentiles). Reference intervals for serum thyroid hormones at 9-14 weeks of gestation derived from the combined group of pregnant women are as follows: TSH, 0.01-2.39 mIU/L; free T4, 11.4-19.5 pmol/L; free T3, 4.23-6.69 pmol/L; total T4, 77.8-182.4 nmol/L; total T3, 1.39-2.97 nmol/L. No differences in the five thyroid parameters' reference intervals are detectable among the ethnic groups except that at study visit 3 (28-32 weeks of gestation), the upper reference limit of total T3 in Malays (3.20 nmol/L; 90% CI, 2.99-3.76 nmol/L) is slightly higher than that in Chinese (2.86 nmol/L; 90% CI, 2.70-2.98 nmol/L). The findings from this study on a multi-ethnic cohort highlight the importance of establishing locally derived and gestational age-specific reference intervals for the five thyroid hormone parameters.