Earticle

Because sows are industrially vital for swine production, monitoring for their health or disorder status is important to ensure high reproductive performance. Especially, ambient temperature changes in different season, especially during summer, are directly influenced to the reproductive performance of sows. Although the serum biochemical parameters are widely applied in the veterinary medicine with wide ranges for the physiological process, the values are also influenced by several factors such as age, breed, gender, and stress. In addition, domestic sows in Koreaspecific reference interval (RI) for serum biochemistry has not been established yet. Therefore, the present study was aimed to evaluate seasonal variation of RIs in the serum biochemistry in domestic sows in Korea at different seasons and to establish normal RIs using a RI finding program (Reference Value Advisor). Significant difference (p < 0.05) on the different seasons were identified in several serum biochemical parameters including BUN, CRE, GGT, GLU, ALB, TP, LDH and Na in sows. Therefore, we further established RIs, specific in domestic sows in Korea regardless of season. The established RIs based on the serum biochemical values provide a baseline for interpreting biochemical results in the domestic sows in Korea, regardless of seasonal effect. It may contribute to develop a strategy for better reproductive performance by improving breeding management practice and evaluating health of pig herds, which facilitate to avert the economic loss in summer infertility in sows.

Background/Aims: The diagnostic accuracy of thyroid dysfunctions is primarily affected by the validity of the reference interval for serum thyroid-stimulating hormone (TSH). Thus, the present study aimed to establish a reference interval for TSH using a normal Korean population. Methods: This study included 19,465 subjects who were recruited after undergoing routine health check-ups. Subjects with overt thyroid disease, a prior history of thyroid disease, or a family history of thyroid cancer were excluded from the present analyses. The reference range for serum TSH was evaluated in a normal Korean reference population which was defined according to criteria based on the guidelines of the National Academy of Clinical Biochemistry, ultrasound (US) findings, and smoking status. Sex and age were also taken into consideration when evaluating the distribution of serum TSH levels in different groups. Results: In the presence of positive anti-thyroid peroxidase antibodies or abnormal US findings, the central 95 percentile interval of the serum TSH levels was widened. Additionally, the distribution of serum TSH levels shifted toward lower values in the current smokers group. The reference interval for TSH obtained using a normal Korean reference population was 0.73 to 7.06 mIU/L. The serum TSH levels were higher in females than in males in all groups, and there were no age-dependent shifts. Conclusions: The present findings demonstrate that the serum TSH reference interval in a normal Korean reference population was higher than that in other countries. This result suggests that the upper and lower limits of the TSH reference interval, which was previously defined by studies from Western countries, should be raised for Korean populations.

Background: Flow cytometry (FC)-based natural killer cell activity (NKA) assays are commonly used in clinical laboratories. As low or no NKA is indicative of hemophagocytic lymphohistiocytosis (HLH), the precise determination of NKA levels is essential. The study aims to establish a reference interval for FC-NKA in healthy Korean subjects and determine the optimal cutoff for diagnosing HLH. Methods: In a single-center retrospective study, internal quality control data from a total of 143 healthy individuals were analyzed. The FC-NKA assessed NK cytotoxicity by culturing effector cells with carboxyfluorescein diacetate succinimidyl ester-labeled K562 cells at an effector-to-target ratio of 32:1 for 4 hours. We compared the assay results among subgroups stratified by age and sex, as well as between healthy controls and HLH patients. Results: The FC-NKA results did not vary significantly depending on age and sex. The reference interval drawn from the 2.5?97.5 percentile of the population was 13.8?82.9%. The lower limits of FC-NKA for the 5th and 10th percentiles were found to be 17.9% and 26.8%, respectively. Using receiver operating characteristic analysis, an optimal cutoff value of 20.0% was identified for HLH diagnosis with a sensitivity and specificity of 93.8% and 93.0%, respectively. The intra-individual coefficient of variation was determined to be 13.4% for the analysis of sequential samples from a single blood donor (N=8). Conclusions: The reference interval of the FC-NKA was determined for healthy Korean subjects, and the suggested cutoff level has the potential to be utilized for the diagnosis of HLH.

To estimate the source of variance components for some hematological parameters and assess the utility of the conventional population-based reference interval, this study computed index of individuality for blood samples, which were from 13 dogs drawn once weekly for 4 consecutive weeks. Results were subjected to nested analysis of variance. For all parameters measured between-dog variations were greater than within-dog variation. Except for the parameters RBC and MCHC the index of individuality was <1.4. The low reliability coefficient and high index of individuality of ${\leq}0.8$ were found for the majority of hematological parameters. In practical term, the present study indicated that use of hemogram profiles alone in the evaluating clinical state of a single patient should be avoided because of their physiological or natural random variations, and that comparing a single measurement on the blood analytes from an individual dog to the conventional population-based reference range may be too insensitive to detect any significant changes in the blood components of that particular dog. A single measurement may not characterize an individual's average concentration of the parameters even shortterm period.

Background: Iron deficiency (ID) and hemoglobinopathies are highly prevalent in South- east Asia. Accurate estimation of reference intervals (RIs) for red cell parameters is compli- cated by the need to exclude individuals with these conditions from the reference popula- tion. Indirect RI estimations using machine learning could help overcome these chal- lenges. Methods: We developed a binary classification model using eXtreme Gradient Boosting (XGB) to distinguish normal individuals from those with ID, hemoglobinopathies, or other anemias. The model was trained on an annotated dataset comprising 5,520 complete blood count (CBC) results and validated with a holdout dataset of 2,367 CBC results. An independent dataset of 64,100 CBC results was used to identify individuals predicted to be normal, from which RIs were estimated using the refineR algorithm. Results: The XGB model achieved an area under the ROC of 0.97 (95% confidence inter- val: 0.96?0.97) for distinguishing between individuals with normal versus abnormal val- ues. Among individuals within the independent dataset, 40,300 (62.9%) were predicted to be normal. The refineR-based reference limits (RLs) derived from this subset approximated those obtained through a direct approach. Improvements in the accuracy of indirect RL es- timates were most evident for hematocrit, hemoglobin, and red cell concentrations. Conclusions: Combining XGB with refineR to indirectly derive RIs for red cell parameters improved the accuracy and yielded results comparable with those of directly derived RIs. A further benefit was the capacity to generate sex- and age-specific ranges, which has re- mained difficult to achieve through direct approaches.

Background: Immature platelet fraction (IPF, %) is a measure of reticulated platelets (RPs), which represents the state of thrombopoiesis. The IPF is obtained from an automated hematology analyzer as one of the platelet parameters. This study was performed to establish reference intervals of IPF and its cut-off values for the differential diagnosis of thrombocytopenia. Methods: Blood samples from 2,039 healthy individuals (1,161 males, 878 females) were obtained to establish reference intervals. The patient group included patients with idiopathic thrombocytopenic purpura (ITP) (N=150) and aplastic anemia (AA) (N=51) with platelet counts of less than 100×109/L. We evaluated the reliability of the IPF measurements, the reference intervals, and cut-off value for the diagnosis of ITP. Results: The reference intervals of IPF were 0.5-3.2% in males and 0.4-3.0% in females (95% confidence interval). The median IPF% of ITP and AA were 7.7% (range, 1.0-33.8%) and 3.5% (range, 0.6-12.9%), respectively. Statistical analysis revealed a significant difference between the IPF% of ITP and AA (P<0.0001). The cut-off value of IPF for differentiating ITP from AA was 7.3% with a sensitivity and specificity of 54.0% and 92.2%, respectively. Conclusions: A rapid and inexpensive automated measurement of IPF can be integrated as a standard parameter to evaluate the thrombopoietic state of the bone marrow. This study determined the reference intervals of IPF from a large population of healthy individuals, including children. Further studies are needed to establish the clinical utility of IPF. (Korean J Lab Med 2010;30:451-9)

Purpose: Elevation in serum alanine aminotransferase (ALT) levels is a biomarker for metabolic syndrome (MS); however, the relationshiphas not been fully investigated within the reference interval of ALT levels. Our objective was to explore the relationship between serum ALT levels within the reference interval and MS in Chinese adults. Materials and Methods: This cross-sectional study included 16028 adults, who attended routine health check-ups at Shengli OilfieldCentral Hospital from January 2006 to March 2012. The reference interval of serum ALT level was defined as less than 40 U/L. Logistic regression models and restricted cubic spline were used to evaluate the association of ALT with MS. Results: The prevalence of MS in the total population was 13.7% (6.4% for females and 18.4% for males). Multiple logistic regressionshowed that ALT levels were positively associated with MS after adjustment for potential confounding factors. The odds ratio of MS in the top quartile was 4.830 [95% confidence interval (CI): 2.980?7.829] in females and 3.168 (95% CI: 2.649?3.790) in males, compared with the ALT levels in the bottom quartile. The restricted cubic spline models revealed a positive non-linear dose-response relationship between ALT levels and the risk of MS in women (p for nonlinearity was 0.0327), but a positive linear dose-response relationship in men (p for nonlinearity was 0.0659). Conclusion: Serum ALT levels within the reference interval are positively associated with MS in a dose-response manner. ElevatedALT levels, even within the reference interval, may reflect early dysmetabolic changes.

Background: Conventional screening for congenital adrenal hyperplasia (CAH) using immunoassays generates a large number of false-positive results. A more specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been introduced to minimize unnecessary follow-ups. However, because of limited data on its use in the Korean population, LC-MS/MS has not yet been incorporated into newborn screening programs in this region. The present study aims to develop and validate an LC-MS/MS method for the simultaneous determination of seven steroids in dried blood spots (DBS) for CAH screening, and to define age-specific reference intervals in the Korean population. Methods: We developed and validated an LC-MS/MS method to determine the reference intervals of cortisol, 17-hydroxyprogesterone, 11-deoxycortisol, 21-deoxycortisol, androstenedione, corticosterone, and 11-deoxycorticosterone simultaneously in 453 DBS samples. The samples were from Korean subjects stratified by age group (78 full-term neonates, 76 premature neonates, 89 children, and 100 adults). Results: The accuracy, precision, matrix effects, and extraction recovery were satisfactory for all the steroids at three concentrations; values of intra- and inter-day precision coefficients of variance, bias, and recovery were 0.7-7.7%, -1.5-9.8%, and 49.3-97.5%, respectively. The linearity range was 1-100 ng/mL for cortisol and 0.5-50 ng/mL for other steroids (R2>0.99). The reference intervals were in agreement with the previous reports. Conclusions: This LC-MS/MS method and the reference intervals validated in the Korean population can be successfully applied to analyze seven steroids in DBS for the diagnosis of CAH.

Background: IgD is an immunoglobulin isotype that accounts for <1% of the total serum immunoglobulin, and IgD level changes can be observed in specific clinical situations. Herein, we evaluated the analytical performances of serum IgD quantification by the SPAPLUS turbidimetric analyzer (The Binding Site, UK), and determined a reference interval of IgD in the Korean population. Methods: Precision, linearity and comparison with BNII (Siemens Healthineers, Germany) were assessed, and a reference interval was established according to the Clinical and Laboratory Standards Institute guidelines. Results: Repeatability ranged from 0.78% to 2.14%, and the within-laboratory precision ranged from 4.10% to 5.40% for three concentrations. The coefficient of determination (R2) was 0.9996 for the analytical measurement range. The IgD concentration showed a correlation between SPAPLUS and BNII (y=0.890x-1.852, r=0.984). However, IgD concentrations tended to be lower in SPAPLUS compared to those in BNII at concentrations >100 mg/L. The established upper limit of the reference interval was 53.6 mg/L. Conclusions: The SPAPLUS shows good analytical performance for serum IgD quantification.

Objectives : This study was conducted to determine the reference interval of serum thyroid hormones(TSH, $FT_3$, $FT_4$) in healthy Korean adults. Methods : Health examination data from 1,591 healthy Korean adults who visited an university hospital were analyzed. Patients with specific health conditions capable of altering laboratory results were excluded from the study. Serum thyroid hormones were measured using IMMULITE 2000 (DPC, USA, 2002). Subjects were 18-65 years old; 911 were male, and 690 were female. Results : The arithmetic means of TSH, $FT_3$, and $FT_4$ values for male subjects were $1.28{\pm}1.84\;{\mu}IU/ml$, $3.23{\pm}0.57\;pg/ml$, and $1.42{\pm}0.22\;ng/dl$, respectively. In female subjects, the arithmetic means of TSH, FT3, and FT4 values were $1.49{\pm}2.08\;{\mu}IU/ml$, $3.08{\pm}0.54\;pg/ml$, and $1.29{\pm}0.24\;ng/dl$, respectively. The arithmetic mean $FT_4$ value for males decreased with age (p<0.01). The arithmetic mean $FT_3$ value for females increased with age (p<0.01). The arithmetic mean thyroid hormone values of all study subjects differed significantly based on season. The arithmetic mean of male $FT_4$ decreased with increasing BMI (p<0.01). The arithmetic mean of female $FT_3$ increased with increasing BMI (p<0.01). The reference intervals recommended by the IMMULITE 2000 manufacturer are $0.40-4.00\;{\mu}IU/ml$ for TSH, 1.80-4.20 pg/ml for $FT_3$, and 0.80-1.90 ng/dl for $FT_4$ (same values for both genders). Conclusions : There was a significant difference in the interval of thyroid hormones between males and females, but the reference interval of IMMULITE 2000 was not established by gender. There is a need to reestablish the reference interval for thyroid hormones in Korean healthy adults.

배경 : 전해질 측정방법과 측정기기가 변함에 따라 전통적인 음이온차의 참고범위를 낮추어야 한다는 주장과 검사전 오차에 의해 음이온차가 큰 영향을 받는다는 지적이 있다. 그러나 본원의 검사기기로는 보고되지 않았고 음이온차에 영향을 미치는 다양한 오차에 대한 연구가 불충분하므로, 검사전 오차를 최소화하여 참고범위를 구하였으며 검사까지의 시간지체나 검체의 공기노출로 인해 참고범위에 영향을 주는지 분석하고자 했다. 방법 : 2004년 11월과 12월 두 달간 본원 건강검진센터에 내원 한 사람 중 혈장 알부민, 크레아티닌과 혈당수치가 정상이며 검진결과 전해질에 영향을 주는 질병이 없다고 판정된 538명을 대상으로 하였다. 혈장 Na+, K+, Cl-, total carbon dioxide (TCO2)를 Hitachi 7170s 자동분석기(Boehringer Mannheim, Indianapolis, USA)로 측정하였다. 정맥피를 주사기 대신 진공채혈관 전용 바늘을 이용해 혈장분리관의 기준량에 맞게 채혈하여서 채혈 중 공기유입으로 인한 오차와 혈장분리관의 용량에 미달해 채혈했을 경우 나타날 수 있는 음이온차의 가성증가를 배제하였다. 혈장분리 후 혈장분리관의 뚜껑을 열고 혈장분리관 채로 카트리지에 넣어 검사하여 CO2 손실을 최대한 방지하였다. 원심분리하기까지 시간지체로 인한 영향과 검체가 공기에 노출된 후 CO2 손실로 인한 영향을 분석하기 위해 채혈로부터 결과가 보고되기까지 시간을 20분 전후로 A군(124명)과 B군(414명)으로 나누어 전해질 및 음이온차를 비교하였다. 음이온차는[Na+-(Cl-+TCO2)]로 구하였다. 결과 : B군의 TCO2가 A군에 비해 평균 0.9 mmol/L 감소하였고 음이온차는 0.6 mmol/L 증가해 유의한 차이를 보였다(각각 P<0.001, P=0.009). 음이온차의 참고범위는 A군을 대상으로 구했으며 5.4-13.4 mmol/L이었다. 결론 : 음이온차의 참고범위는 여러 오차들에 의한 차이를 배제한 후에도 기존에 쓰이던 범위보다 낮아 새로운 기준으로 바꿔야 하며, 참고범위 설정시 검사까지의 시간지연과 검체의 공기노출을 최소화해야 한다고 생각된다.

Background : The reference interval of anion gap established in the 1970s has been changing as the method of electrolyte measurement changes. It is also influenced by preanalytical errors. But there are only a few reliable reports that examined the effect of various preanalytical errors. Furthermore, there has been no report of values measured by the instrument being used in our laboratory. Therefore, we attempted to establish a reference interval of anion gap measured by Hitachi 7170s minimizing preanalytical errors, and analyzed the effect of a delay in electrolyte measurement and of sample exposure to the air. Methods : The subjects were 538 healthy people who attended Hanyang university hospital health clinic with normal blood levels for albumin, creatinine and glucose. The plasma Na+, K+, Cl-, and total carbon dioxide (TCO2) were measured by Hitachi 7170s autoanalyzer (Boehringer Mannheim, Indianapolis, USA). To examine the effect of the delay between blood withdrawal and electrolyte measurement and the loss of CO2 by exposure to the room air after bottle opening, the subjects were divided into group A (124 subjects) and group B (414 subject) whose electrolyte results were reported within and after 20 minutes, respectively, of blood withdrawal and the two groups were compared with each other for the electrolytes and anion gap. Anion gap was calculated by the formula, [Na+- (Cl-+TCO2)]. Results : Compared with group A, TCO2 of group B decreased by 0.9 mmol/L (P<0.001) and the anion gap increased by 0.6 mmol/L (P=0.009). The reference interval of anion gap was established based on the group A at the value of 5.4-13.4 mmol/L. Conclusions : The reference interval of anion gap determined in this study was lower than the value commonly used and should be established with a minimum delay in electrolyte measurement and sample exposure to the air.

배경: 전혈 점도는 혈액이 혈관을 통과할 때 발생하는 내부 저항을 의미한다. 이러한 전혈 점도는 기존의 연구를 통해 심혈관 및 뇌혈관질환을 비롯한 많은 질병과 관련이 있는 것으로 밝혀졌다. 본연구에서는 전혈 점도 측정을 위해 새로 개발된 미세유체역학 혈액점도계 Viscore-300 (NanoBiz, Korea)의 분석적 성능 평가와 참고범위를 설정하였다. 방법: 세 가지 정도관리물질을 사용하여 20일 동안 240번의 측정을 통하여 정밀도 평가를 수행하였다. 재현성 평가를 위해 3개의전혈 검체를 하루 동안 60번 측정하였다. 또한 정확도 평가를 위해CLSI 가이드라인에 따라 100개의 전혈 검체를 이용하여 회전식 점도계 DV3T (Brookeld, USA)와 비교하였다. 전혈 점도의 참고범위를 122명의 건강인을 대상으로 설정하였다. 결과: 정밀도 및 재현성 평가 결과 세 가지 물질과 두 전단율 모두에서 5% 미만의 변이 계수를 보였다. 정확도 평가 결과, 평가장비와비교장비의 평균 차이는 10 s–1과 300 s–1의 전단율에서 각각 0.09 cP 및 –0.07 cP이었다. 전혈 점도의 참고범위는 남자에서 저전단율10 s–1하에서 6.88–13.52 cP, 고전단율 300 s–1하에서 4.32–6.43 cP로측정되었다. 여자에서는 저전단율 10 s–1하에서 5.74–13.29 cP, 고전단율 300 s–1하에서 3.60–6.12 cP로 측정되었다. 결론: Viscore-300은 기존 회전식 점도계 DV3T와 비교했을 때 정밀도가 우수하였고, 정확한 점도 측정 결과를 보였다. 따라서 본연구에서 평가한 새로운 혈액점도계는 임상검사실에서 임상 진료과의 요구에 맞춰 정확하고 신속하게 전혈 점도를 보고할 수 있을것으로 판단되었다.

Background: Whole blood viscosity (WBV) refers to the internal resistance that occurs when blood flows through blood vessels. WBV is known to be related to many diseases including cardiovascular and neurovascular diseases. We have investigated the analytical performance and established reference intervals for a newly developed microfluidic viscometer, Viscore-300 (NanoBiz, Korea), used for the measurement of WBV. Methods: We performed a precision test of 240 measurements over 20 days using three control materials. For evaluation of repeatability, a total of 60 WBV measurements were made in 3 whole blood samples 20 times a day. A total of 100 whole blood samples were used to evaluate the accuracy of the Viscore-300 in comparison to a rotating viscometer, DV3T (Brookfield, USA), in accordance with the the Clinical and Laboratory Standards Institute’s guidelines. To establish the reference intervals, 122 healthy individuals were enrolled in this study. Results: The precision and repeatability results showed that the CV was less than 5% for three samples and two shear rates. In the accuracy test, the mean differences between two viscometers were 0.09 cP (0.9%) and ?0.07 cP (?1.4%) at shear rates of 10 s?1 and 300 s?1, respectively. The reference intervals of WBV for men were 6.88?13.52 cP at 10 s?1 and 4.32?6.43 cP at 300 s?1; those of women were 5.74?13.29 cP at 10 s?1 and 3.60?6.12 cP at 300 s?1. Conclusions: Viscore-300 showed excellent precision and accuracy and it might be a good instrument for reporting WBV quickly and accurately.

HE4는 CA125와 함께 난소의 양성과 악성 종양을 감별하는 새로운 표지자이다. 난소 종괴가 있는 환자를 난소암 발생 고위험군과 저위험군으로 구분하기 위해 HE4, CA125와 폐경 유무를 조합한 risk of ovarian malignancy algorithm (ROMA)가 제안되었다. 한국인에서 설정한 HE4의 정상 참고범위는 제조사 권장 참고범위나 중국인을 대상으로 한 참고범위와 차이가 있었다.

Human epididymis protein 4 (HE4), which complements cancer antigen 125 (CA125), has emerged as a new diagnostic biomarker that can discriminate between benign and malignant ovarian tumors. The risk of ovarian malignancy algorithm (ROMA) incorporates CA125, HE4, and menopausal status to classify patients with pelvic masses into those at high or low risk of developing ovarian cancer. The reference interval of HE4 among Korean population was different from those recommended by the manufacturer or evaluated in the Chinese.