Because SAA is a rapidly responsive acute phase protein, the proposed interval should be interpreted as an assay- and population-specific RI rather than as a disease-classification decision limit.
Abstract
Introduction Serum amyloid A (SAA) is a major acute phase protein used as an inflammatory biomarker in equine medicine. However, no universally accepted assay-specific reference interval (RI) exists for donkeys, and available literature remains limited, with only few studies using different donkey breeds and immunoassay platforms. This study aimed to establish an assay- and population-specific RI for serum SAA in apparently healthy donkeys using a species-specific double sandwich ELISA. Methods Serum SAA concentrations were measured in 176 apparently healthy donkeys. RI estimation followed ASVCP/CLSI recommendations. The primary RI was calculated nonparametrically as the central 95% interval from all reference individuals, and two-sided 90% confidence intervals (CIs) for the reference limits were estimated nonparametrically. Data were inspected using Tukey’s interquartile fences; however, high-end observations were not excluded from the primary RI analysis. Exploratory analyses were performed to assess the need for partitioning by sex, age, or breed. Results The nonparametric RI for serum SAA was 2.91–42.85 ng/mL. The 90% CI for the lower reference limit was 0.00–4.07 ng/mL, and the 90% CI for the upper reference limit was 35.49–67.10 ng/mL. Exploratory analyses did not support partitioning by sex, age, or breed. The relatively broad CI for the upper reference limit indicated imprecision, likely reflecting the influence of a minority of high-end observations. Discussion The low SAA concentrations observed in this study are consistent with findings reported in horses. Differences between this and previous donkey studies may reflect variation in assay platform, sample size, management conditions, physiological state, or population characteristics. Because SAA is a rapidly responsive acute phase protein, the proposed interval should be interpreted as an assay- and population-specific RI rather than as a disease-classification decision limit. Clinical interpretation should therefore always consider the individual donkey’s clinical context.
The findings underscore the need for caution when interpreting the estimated values in clinical settings and because rehabilitated individuals may appear clinically stable while harboring subclinical pathologies, the results of this study should be considered within the context of rehabilitation.
Jang-Hee Han, Jinyoung Kim, Soeun Ryu et al.· Journal of zoo and wildlife...· 0 citations
Background: Reliable interpretation of serum free triiodothyronine (fT3) depends on reference intervals reflect the
population served by the reporting laboratory. Most Syrian laboratories currently apply the manufacturer’s generic
euthyroid range (2.0–4.4 pg/mL), derived from Western cohorts whose nutritional, environmental, and disease profiles
differ substantially from those of a population endured fourteen years of armed conflict. No population-specific fT3
reference data have been reported for Syria.
To derive age- and sex-stratified fT3 reference intervals for the Syrian population using the indirect method, to quantify
the discrepancy between locally derived and manufacturer-supplied limits, and to characterise the inter-analyte
correlation structure among fT3, fT4, and TSH.
Methods: Retrospective extraction of 10,020 fT3 results from a single high-throughput clinical laboratory in Damascus
(January 2020–December 2024) was performed. After applying exclusion criteria, 1,999 results were eligible. Reference
intervals were derived by iterative mean ± 2 SD trimming across six age–sex subgroups. All measurements were
performed on the Roche cobas e 411 using the Elecsys FT3 III assay (ECLIA). Paired thyroid panels (fT3, fT4, TSH; n =
1,197) were analysed using Pearson, Spearman, and partial correlation methods.
The derived adult fT3 reference interval was 1.49–5.38 pg/mL for females and 1.32–5.70 pg/mL for males substantially
wider than the manufacturer’s range, with the lower limit displaced downward by 0.51–0.68 pg/mL and the upper limit
shifted upward by 0.98–1.30 pg/mL. Serum fT3 declined with age (Spearman ρ = −0.226, p < 0.001; ANOVA F = 8.88,
p < 0.001), while no clinically meaningful sex difference was observed (Cohen’s d = −0.008). Among 1,197 paired
panels, the fT3–fT4 Spearman correlation was ρ = 0.353 and the fT3–TSH correlation was ρ = −0.336, attenuated to
−0.246 after controlling for fT4. Application of the manufacturer’s generic range would misclassify approximately 7.8%
of Syrian adults as having abnormal fT3 (3.6% false-low, 4.3% false-high). Conclusions: The manufacturer’s generic fT3 reference range misclassifies a clinically significant proportion of Syrian
adults at both the hypothyroid and hyperthyroid boundaries. Adoption of the locally derived, age-stratified reference
intervals reported here is recommended for Syrian laboratories using the Roche.
Z. Malek, Nasser Thallaj, Adnan M. Al-Khatib et al.· Journal of Medical Sciences...· 0 citations
BACKGROUND
Total adiponectin (TA) is a marker of metabolic health in equids, with values below a critical decision point of < 7.9 μg/mL conferring increased risk of laminitis.
OBJECTIVES
To evaluate an IT assay to measure serum [TA] in equids and to assess its correlation with [high molecular weight adiponectin] (HMWA) measured by ELISA.
METHODS
Total serum adiponectin concentrations from 207 adult horses were measured using both an IT assay for TA and HMWA using a previously validated ELISA assay. Data were analyzed using Spearman correlation and Passing-Bablok regression. Intra- and inter-assay precision, linearity, lower limit of quantification (LLoQ), and freeze-thaw stability were assessed for the [TA] assay.
RESULTS
Mean (range) intra-assay coefficient of variation (CV%) was 2.3% (1.8%-2.8%); inter-assay, across-day CV% was 3.3% (3.25%-3.4%), and across reagent lot CV was 11.7% (9.0%-17.9%). Mean recovery upon dilution was 133.7% (122.6%-140.6%), and LLoQ 1.3 μg/mL. The median CV for 5 freeze-thaw cycles was 3.0% (range 1.0%-3.0%) with a median change in concentration of -11% (range -[9.9-17.1]%). A strong correlation between [TA] and [HMWA] is observed (ρ = 0.90 [95% confidence interval 0.86-0.92], p < 0.001), although in 18% of samples, [HMWA] > [TA].
CONCLUSIONS
The turbidimetric immunoassay is sufficiently precise and reliable for measurement of [TA] in equids, especially around the critical decision point, and LLoQ was below the lowest clinical cut-off value. [TA] overall correlated well with [HMWA] in this population, although instances of higher [HMWA] than [TA] were noted at high [HMWA].
Rose D. Nolen-Walston, Caitrin R Lowndes, J. Kulp et al.· Veterinary clinical patholog...· 0 citations
BACKGROUND
Growing interest surrounds circulating biomarkers for assessing neuromuscular integrity and muscle health. C-terminal agrin fragment (CAF) has emerged as a promising marker associated with sarcopenia, ageing, and renal dysfunction. Limited reference data and insufficient characterisation of preanalytical factors restrict clinical application.
METHODS
This study established a reference interval for CAF in lithium-heparin (Li-heparin) plasma and investigated key preanalytical variables influencing CAF measurements using the Abcam ab216945 ELISA. Plasma samples from 120 healthy adult blood donors were used to determine reference intervals. CAF concentrations were measured using a commercial ELISA. Stability was assessed at room temperature, during storage at -20 °C, after freeze-thaw cycles, and after delayed centrifugation. Matrix comparison between Li-heparin and K-EDTA plasma was performed in 28 paired samples.
RESULTS
The overall non-parametric reference interval for CAF in Li-heparin plasma was 2917.5-5877.0 pg/mL (median 4260.0 pg/mL). A weak positive association between CAF concentration and age was observed, but no sex-related difference. CAF remained stable for up to seven days at room temperature, up to three freeze-thaw cycles and up to at least five hours of delayed centrifugation. Storage at -20 °C was acceptable up to 30 days only and showed increased individual variability already present after 14 days. Matrix comparison demonstrated an average bias of 14.6% between Li-heparin and K-EDTA plasma.
CONCLUSIONS
CAF demonstrates acceptable stability in Li-heparin plasma under standard laboratory conditions. The study establishes a CAF reference interval in Li-heparin and identifies matrix-dependent differences, supporting improved analytical standardisation and interpretation of CAF measurements.
J. R. Therkildsen, C. S. Knudsen, J. H. Storgaard et al.· Clinica chimica acta; intern...· 0 citations
BACKGROUND
C-reactive protein (CRP) is a biomarker of systemic inflammation in dogs. There is limited data on inter-laboratory comparability of the results or the effects of long-term storage.
OBJECTIVES
(1) Compare CRP measurements across three institutions utilizing the same assay. (2) Evaluate 2-year stability of CRP in canine serum stored at -80°C.
METHODS
Canine serum was collected and pooled to obtain 100 samples, which were distributed among three veterinary clinical pathology laboratories and evaluated using the same commercially available canine CRP assay. Method comparison was performed according to current recommendations. A subset of samples was then stored at -80°C for 2 years and re-analyzed to assess long-term stability.
RESULTS
Passing-Bablok and Bland-Altman analyses revealed statistically significant constant and proportional bias between the three laboratories. However, the clinical impact was minimal (mean difference percentages were 4.0%-15.6% and mean difference absolute values were 0.9-4.0 mg/L), differences rarely exceeded the total allowable error (30%), and only two samples crossed the 10 mg/L inflammation decision limit. Similarly, re-testing after storage revealed a statistically significant increase in CRP concentration (mean difference of 0.75 mg/L, p < 0.001). However, only one sample exhibited a change greater than 30%, and the mean percentage change across all samples was 9.0%. Long-term storage did not cause any samples to cross the clinical inflammation decision limit.
CONCLUSIONS
While there was statistical evidence of differences between laboratories and after long-term storage, it was unlikely to alter clinical interpretation or patient management.
Marion Cambrelin, Amanda F. Bettag, Lorraine E. Prevost et al.· Veterinary clinical patholog...· 0 citations
BACKGROUND
Accurate reference intervals (RIs) for laboratory test results are essential in clinical practice. To enhance clinical decision-making, refined RIs are needed. Therefore a single-center study was performed with extensively evaluated healthy participants, measuring a large set of biochemical markers.
METHODS
In this descriptive, quantitative, a priori direct sampling, single-center study, a total of 18,701 determinations were collected from 8380 healthy adults aged 18 years and older. Age- and sex-specific RIs were established for 36 biochemical assays.
RESULTS
Serum concentrations of several biochemical assays remained relatively constant across the adult age range and were similar between sexes (e.g., total calcium, chloride and sodium). Other biochemical assays (e.g., alanine-amino transferase, triglycerides) showed differences, indicating the influence of factors such as age and sex on the observed results.
CONCLUSIONS
For the first time in Europe, we established age- and sex-specific RIs for 36 biochemical assays using data from extensively clinically validated healthy participants.
R. O. Elferink, Shirly A M Wübbels, Geert Sloots et al.· Clinica chimica acta; intern...· 0 citations
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