Lower Limit Of Reference Interval Research Articles

Reference intervals of anti‐Müllerian hormone in Korean women

BackgroundLimited data are available with reference intervals of serum anti‐Müllerian hormone (AMH) level in Korean women.MethodsWe retrospectively reviewed serum AMH test results performed with automated electrochemiluminescence immunoassay in Korean women who visited health promotion centers between January 2019 and December 2020. Serum AMH results by age group were compared with previously reported reference intervals.ResultsDuring the 2‐year study period, a total of 1953 AMH test results from Korean women (age 20–49 years) undergoing general health checkups were obtained. Serum AMH level differed significantly by age group. Peak AMH level was observed at age 25–29 years and decreased to undetectable for subjects older than 44 years. The 2.5th, 5th, and 10th percentile values of the present study were comparable with previously assessed lower limits of reference intervals. The upper limit of the reference interval defined as the 97.5th percentile value in women younger than 35 years was higher than that of Western populations. The 90th percentile value of the present study population was similar to the 95th or 97.5th percentile value of reference intervals for Western populations of women younger than 35 years.ConclusionUnderstanding patient populations and differences in reference intervals by age group and measurement method can help guide clinical decisions and clinical laboratory analysis.

Postoperative Vitamin Profile after Receiving a Novel Peripheral Parenteral Nutrition Solution: Multicenter Randomized Controlled Phase III Trial

Introduction: We assessed the efficacy and safety of OPF-105, a novel all-in-one peripheral parenteral nutrition (PPN) solution containing multivitamins by the U.S. Food and Drug Administration in 2000 (FDA2000 recommendation). Methods: We conducted a phase III trial administering OPF-105 or BFL (combination of a commercially available PPN solution and fat emulsion) to patients after gastrointestinal (GI) tract surgery from postoperative day (POD) 1 up to POD14. Until POD7, nutrients were provided only with OPF-105 or BFL. After blood sampling on POD8, oral food intake was permitted. PPN was administered according to the amount of food intake. Results: Efficacy endpoints were assessed in 99 subjects (OPF group: 52; BFL group: 47). The levels of blood proteins and fatty acids in the two groups were similar on POD8. The transition of these mean levels was similar in both groups from POD1 or 2 to POD9 to 15. The mean preoperative blood vitamin levels were within reference intervals (RIs). On POD1 (before administration), the mean levels of most blood vitamins decreased compared to those of the preoperative levels. In the BFL group, the mean blood levels of vitamin B2, B6, pantothenic acid (PA), folic acid (FA), biotin, and C decreased below or near the lower limit of RIs on POD8, and the mean blood levels of vitamin B6 and C remained low from POD9 to 15. In the OPF group, the mean blood levels of vitamins, excluding vitamin K, were within RIs on POD8 and POD9 to 15. The mean levels of blood vitamin K increased over the upper limit of RIs on POD8 but within RIs from POD9 to 15. There was no obvious difference in the incidence of adverse events between the two groups, which is common after GI tract surgeries. Conclusion: Blood vitamin levels decreased when patients were administered PPN without vitamin supplementation during the first week after surgery. The novel PPN formula containing multivitamins recommended by FDA2000 can be safely administered to postoperative patients to maintain blood vitamin levels.

Age and seasonal variation and establishment of reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry

ObjectivesWe aimed to establish reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry to improve the diagnosis of vitamin deficiency and outcomes of associated conditions. MethodsIn this retrospective analysis of 24 810 specimens, we aimed to examine sex-, age-, and season-related variations in vitamin levels in different groups, set reference-value intervals for vitamin levels, and evaluate these reference values against those recommended by manufacturers. ResultsLevels of vitamins B3, B5, B6, B7, and B12 were higher, and those of vitamins B2, B9, and C were lower, in men than in women. There were seasonal variations in levels of vitamins B1, B3, B5, B6, B9, B12, and C. Levels of vitamins B1, B2, B3, B5, B6, B7, B9, and C differed across age groups; vitamin B1 displayed significant differences between ages 0 to 14 years and adults compared with reference change values. The lower limits of vitamins B1 (ages 15–100 y), B2, B3, B7, and C were lower, and that of vitamin B5 was higher, than the recommended reference values. Finally, the upper limits of vitamins B1, B3, B5, B6, and B7 were lower than the recommended values. ConclusionsFor values obtained using liquid chromatography tandem mass spectrometry, the lower limits of reference intervals for vitamins B1 (ages 15–100 y), B2, B3, B7, and C should be lowered, that of vitamin B5 should be raised, and the upper limits of reference intervals for vitamins B1, B3, B5, B6, and B7 should be lowered.

Reference Interval for Korean Serum Folate Assay Traceable to the WHO International Standard.

Little is known about the reference interval of serum folate concentration if using recently re-standardized assays traceable to the World Health Organization (WHO) international standard reference 03/178 in a Korean population. This study aimed to investigate serum folate levels in Korean subjects without macrocytic anemia or increased homocysteine, for the assessment of folate deficiency. We retrospectively reviewed data from Korean adults whose hemoglobin, mean corpuscular volume, and serum total homocysteine values were within reference limits. The median (interquartile range) serum folate level was 7.8 (5.4 - 12.6) ng/mL in men and 10.2 (6.9 - 15.6) ng/mL in women. The reference interval for serum folate (2.5th and 97.5th percentiles) ranged from 2.9 to 38.0 ng/ mL. From among 723 Korean adults, the lower limit of reference intervals of serum folate for folate deficiency, defined as the 2.5th percentile, was 2.9 ng/mL. The prevalence of folate deficiency was higher in men (6.5%) than in women (1.2%, p < 0.05) when a cutoff value of 3.0 ng/mL was applied. Using the cutoff value of 4 ng/mL for folate deficiency, which is in accordance with the instructions from the manufacturer of the new assay and the WHO 2012 guideline for homocysteine as a metabolic indicator before assay standardization, about 5% of subjects were reclassified as folate deficient. Our study suggests that any change of reference limits using a re-standardized assay needs to be verified in clinical laboratories.

Clinical thresholds for diagnosing iron deficiency: comparison of functional assessment of serum ferritin to population based centiles

Low serum ferritin is diagnostic of iron deficiency, yet its published lower cut-off values are highly variable, particularly for pediatric populations. Lower cut-off values are commonly reported as 2.5th percentiles, and is based on the variation of ferritin values in the population. Our objective was to determine whether a functional approach based on iron deficient erythropoiesis could provide a better alternative. Utilizing 64,443 ferritin test results from pediatric electronic health records, we conducted various statistical techniques to derive 2.5th percentiles, and also derived functional reference limits through the association between ferritin and erythrocyte parameters: hemoglobin, mean corpuscular volume, mean cell hemoglobin concentration, and red cell distribution width. We find that lower limits of reference intervals derived as centiles are too low for clinical interpretation. Functional limits indicate iron deficiency anemia starts to occur when ferritin levels reach 10 µg/L, and are largely similar between genders and age groups. In comparison, centiles (2.5%) presented with lower limits overall, with varying levels depending on age and gender. Functionally-derived limits better reflects the underlying physiology of a patient, and may provide a basis for deriving a threshold related to treatment of iron deficiency and any other biomarker with functional outcomes.

Study of total error specifications of lymphocyte subsets enumeration using China National EQAS data and Biological Variation Data Critical Appraisal Checklist (BIVAC)-compliant publications.

It is important to select proper quality specifications for laboratories and external quality assessment (EQA) providers for their quality control and assessment. The aim of this study is to produce new total error (TE) specifications for lymphocyte subset enumeration by analyzing the allowable TE using EQAS data and comparing them with that based on reliable biological variation (BV). A total of 54,400 results from 1,716 laboratories were collected from China National EQAS for lymphocyte subset enumeration during the period 2017-2019. The EQA data were grouped according to lower limits of reference intervals for establishing concentration-dependent specifications. The TE value that 80% of laboratories can achieve were considered as TE specifications based on state of the art. The BV studies compliant with Biological Variation Data Critical Appraisal Checklist (BIVAC) were used to calculate the three levels of TE specifications. Then these TE specifications were compared for determining the recommended TE specifications. Four parameters whose quality specifications could achieve the optimum criteria were as follows: the percentages of CD3+, CD3+CD4+ (high concentration) and CD3-CD16/56+ cells, and the absolute count of CD3-CD16/56+ cells. Only the TE specifications of CD3-CD19+ cells could achieve the minimum criteria. The TE specifications of remaining parameters should reach the desirable criteria. New TE specifications were established by combining the EQA data and reliable BV data, which could help laboratories to apply proper criteria for continuous improvement of quality control, and EQA providers to use robust acceptance limits for better evaluation of EQAS results.

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.

Assessment of average of normals (AON) procedure for outlier-free datasets including qualitative values below limit of detection (LoD): an application within tumor markers such as CA 15-3, CA 125, and CA 19-9

Average of normals (AON) is a quality control procedure that is sensitive only to systematic errors that can occur in an analytical process in which patient test results are used. The aim of this study was to develop an alternative model in order to apply the AON quality control procedure to datasets that include qualitative values below limit of detection (LoD). The reported patient test results for tumor markers, such as CA 15-3, CA 125, and CA 19-9, analyzed by two instruments, were retrieved from the information system over a period of 5 months, using the calibrator and control materials with the same lot numbers. The median as a measure of central tendency and the median absolute deviation (MAD) as a measure of dispersion were used for the complementary model of AON quality control procedure. The ubias values, which were determined for the bias component of the measurement uncertainty, were partially linked to the percentages of the daily median values of the test results that fall within the control limits. The results for these tumor markers, in which lower limits of reference intervals are not medically important for clinical diagnosis and management, showed that the AON quality control procedure, using the MAD around the median, can be applied for datasets including qualitative values below LoD.

Evaluation of the short-term stability of specimens for clinical laboratory testing.

A major concern in both the laboratory-medicine and research communities is the quality of human specimens for analysis. However, there is insufficient scientific evidence regarding optimal conditions for handling and storing routine specimens, especially those in liquid form. Thus, we investigated the stability of clinically relevant samples stored under various conditions. Ten clinical laboratories in Japan conducted analyses of the stability of post-clinical (left over after analysis) test samples in relation to temperature and storage duration. We examined serum, whole blood, and urine samples submitted to each laboratory for routine testing. In this study, at least 5 samples for each of 35 tests were analyzed at each laboratory. After completion of routine testing, specimens with sufficient residual volume and values between LL-R/2 (lower limit of reference interval) and UL+R/2 (upper limit) were divided into 300 μL aliquots, where R=UL - LL. Aliquots of serum specimens were stored at either room temperature (23°C), 4°C, -20°C, or -80°C without light exposure. Aliquots of whole blood and urine specimens were stored at either 23°C or 4°C. The storage time was either 1, 3, or 7 days. Average differences between pre- and post-storage test results were evaluated for each laboratory test by two-way ANOVA. F-values for between-day variations were used for judging the statistical significance of storage-related changes in test values, whereas the ratio of between-day SD to between-individual SD (one-fourth of reference interval) was used to indicate the practical significance of the change. Sample denaturation is clearly temperature- and storage-duration dependent for almost all analytes. In general, specimens were most susceptible to denaturation at 23°C, then 4°C, -20°C, and -80°C. This study confirmed the accumulated routine, practice-based, detailed knowledge regarding specimen stability and will help to ensure the reliability of laboratory test results.

Establishment of Reference Interval for Liver Specific Biochemical Parameters in Apparently Healthy North Indian Population

Reference intervals (RI) are the most common decision support tool used for interpretation of numerical laboratory reports. The quality of the RI can play as large a role in result interpretation as the quality of the result itself. As such there is hardly any study examining RI for liver specific biochemical parameters in Indian population especially north Indians having drastically different food habits as compared to rest of the India. So there is a need to establish the RI for north Indian population. Present study was conducted on 2,021 apparently healthy individuals of north Indian origin ranging in age from 15-60years, were selected randomly using defined criteria. Lipemic, hemolysed, icteric and stored samples were also excluded adopting preanalytical criteria for rejection of sample. Non parametric methodology for determination of RI was adopted as most of the biochemical parameters included revealed non Gaussian distribution. Data were analyzed for middle 95 percentile (2.5th-97.5th percentile), median and 95% confidence interval using SPSS software package version 10.0. The upper and the lower limit of RI (reported Vs observed) for bilirubin (0-1.2 Vs 0.30-1.30mg/dL), serum glutamate oxaloacetate transferase (SGOT) (0-41 Vs 13-52.80IU/L), serum glutamate pyruvate transferase (SGPT) (0-50 Vs 10-68IU/L) showed wide variation as compared to reported standard RI however Gamma glutamyl transferase (GGT) (0-50 Vs 5.00-50.60IU/L) remained within the reported standard RI. Further gender wise evaluation revealed higher cutoff in males (AST 14-55, ALT 11-70.35, GGT 6.76-51.09 in IU/L, bilirubin (0.40-1.34mg/dL) as compared to females (SGOT 13-50.43, SGPT 9-63.43, GGT 3.92-48.70 in IU/L, Bilirubin 0.30-1.20mg/dL) for both enzymatic and non enzymatic biochemical parameters. The variations may be attributed to dietary pattern smoking and alcoholism.

Post prandial plasma glucose level less than the fasting level in otherwise healthy individuals during routine screening

During routine screening, some otherwise healthy individuals who showed remarkably lower post prandial (at 2 hour) plasma glucose without any symptom were subjected to extended glucose tolerance test and a few of them to extended post meal tolerance test as well. It was observed that post prandial (at 2 hour) plasma glucose after glucose administration was significantly lower than the fasting level (p<0.05-p<0.001). However, post prandial plasma glucose at 2 hour after their usual meal exhibited a significantly higher level than the fasting and post glucose level (p<0.05-p<0.001). Glucose appears to be a stronger agent than the more natural mixed meal in these individuals in causing post prandial lowering of plasma glucose. Hence, these individuals are to be evaluated with their usual meals before considering further investigations. Like upper limit, there is the need to have a consensus lower limit of reference interval of blood glucose level.

Serum hemopexin in patients with dermatitis herpetiformis on dapsone (di(4-aminophenyl)sulphone).

Twenty patients with dermatitis herpetiformis treated with di(4-aminophenyl)-sulphone (Dapsone) were analyzed with respect to serum hemopexin concentration as well as some other haematological parameters. With one exception, there were normal concentrations of serum hemopexin when the haptoglobin and methaemoglobin concentrations were normal. Ten out of 11 patients with haptoglobin below 0.3 g/l, which is the lower limit of reference interval at this laboratory, had their hemopexin concentrations reduced to various extents. There was an inverse relationship between the concentration of serum hemopexin and blood methaemoglobin. There was no correlation between amount of Heinz bodies and the concentrations of blood methaemoglobin, serum haptoglobin or serum hemopexin. It is concluded that serum hemopexin measurement should be of value in the assessment of the severity of the haemolysis caused by the drug treatment in those cases who have a low serum haptoglobin concentration.