Objective:To investigate the prevalence of Kashin-Beck disease (KBD) in Liaoning Province, analyze its disease progression, and provide a scientific basis for timely adjustment in prevention and control strategies and work priorities.Methods:From March 2019 to October 2024, a cross-sectional study was conducted in five KBD endemic townships in Liaoning Province. The monitoring was conducted on a village by village basis, including the name of the administrative village, the name of the natural village (township), the number of permanent households (residing for ≥6 months), the number of permanent residents, the number of permanent residents aged 7 to 12, the management and treatment of adult patients, the implementation of prevention and control measures, and the implementation of child nutrition improvement programs (grain replacement). Anteroposterior X-rays of both hands were taken for children with abnormal signs or suspected KBD. Cases were confirmed as KBD if both clinical examination and X-ray review were positive. Five-year KBD surveillance data were analyzed, including the numbers of clinically positive and X-ray positive cases at each monitoring site, with positive detection rates calculated to macroscopically analyze the dynamic changes in KBD status.Results:From 2019 to 2024, a total of 180 103 children aged 7 - 12 years old were monitored in KBD endemic villages in Liaoning Province. Among them, 321 children showed abnormal clinical signs, but hand X-rays revealed no positive changes indicative of KBD. The annual positive detection rate for KBD was 0 throughout the study period. In 2024, in 1 500 endemic natural villages (hamlets) in Liaoning Province, 39 205 acres of farmland were converted to economic crops (1.96% of original farmland), and 16 520 acres were returned to forest or grassland (1.74% of original farmland). There were 534 KBD patients, with a prevalence rate of 6.7/10 000. All patients had completed patient information management, follow-up evaluation, achieving a 100% management rate. Four hundred thirty-five patients with Kashin Beck disease were planned for treatment, but, 476 patients were actually treated with medication, resulting in a planned treatment completion rate of 109.43% and a patient treatment rate of 89.14%.Conclusion:From 2019 to 2024, Liaoning Province has achieved the goal of eliminating KBD and maintained sustained elimination status.

Objective:To investigate the prevalence of Kashin-Beck disease (KBD) in Liaoning Province, analyze its disease progression, and provide a scientific basis for timely adjustment in prevention and control strategies and work priorities.Methods:From March 2019 to October 2024, a cross-sectional study was conducted in five KBD endemic townships in Liaoning Province. The monitoring was conducted on a village by village basis, including the name of the administrative village, the name of the natural village (township), the number of permanent households (residing for ≥6 months), the number of permanent residents, the number of permanent residents aged 7 to 12, the management and treatment of adult patients, the implementation of prevention and control measures, and the implementation of child nutrition improvement programs (grain replacement). Anteroposterior X-rays of both hands were taken for children with abnormal signs or suspected KBD. Cases were confirmed as KBD if both clinical examination and X-ray review were positive. Five-year KBD surveillance data were analyzed, including the numbers of clinically positive and X-ray positive cases at each monitoring site, with positive detection rates calculated to macroscopically analyze the dynamic changes in KBD status.Results:From 2019 to 2024, a total of 180 103 children aged 7 - 12 years old were monitored in KBD endemic villages in Liaoning Province. Among them, 321 children showed abnormal clinical signs, but hand X-rays revealed no positive changes indicative of KBD. The annual positive detection rate for KBD was 0 throughout the study period. In 2024, in 1 500 endemic natural villages (hamlets) in Liaoning Province, 39 205 acres of farmland were converted to economic crops (1.96% of original farmland), and 16 520 acres were returned to forest or grassland (1.74% of original farmland). There were 534 KBD patients, with a prevalence rate of 6.7/10 000. All patients had completed patient information management, follow-up evaluation, achieving a 100% management rate. Four hundred thirty-five patients with Kashin Beck disease were planned for treatment, but, 476 patients were actually treated with medication, resulting in a planned treatment completion rate of 109.43% and a patient treatment rate of 89.14%.Conclusion:From 2019 to 2024, Liaoning Province has achieved the goal of eliminating KBD and maintained sustained elimination status.

Objective:To examine the impact of varied surgical treatment strategies on the prognosis of patients with initial resectable gastric cancer liver metastases (IR-GCLM).Methods:This is a retrospective cohort study. Employing a retrospective cohort design, the study selected clinicopathological data from the national multi-center retrospective cohort study database, focusing on 282 patients with IR-GCLM who underwent surgical intervention between January 2010 and December 2019. There were 231 males and 51 males, aging ( M(IQR)) 61 (14) years (range: 27 to 80 years). These patients were stratified into radical and palliative treatment groups based on treatment decisions. Survival curves were generated using the Kaplan-Meier method and distinctions in survival rates were assessed using the Log-rank test. The Cox risk regression model evaluated HR for various factors, controlling for confounders through multivariate analysis to comprehensively evaluate the influence of surgery on the prognosis of IR-GCLM patients. A restricted cubic spline Cox proportional hazard model assessed and delineated intricate associations between measured variables and prognosis. At the same time, the X-tile served as an auxiliary tool to identify critical thresholds in the survival analysis for IR-GCLM patients. Subgroup analysis was then conducted to identify potential beneficiary populations in different surgical treatments. Results:(1) The radical group comprised 118 patients, all undergoing R0 resection or local physical therapy of primary and metastatic lesions. The palliative group comprised 164 patients, with 52 cases undergoing palliative resections for gastric primary tumors and liver metastases, 56 cases undergoing radical resections for gastric primary tumors only, 45 cases undergoing palliative resections for gastric primary tumors, and 11 cases receiving palliative treatments for liver metastases. A statistically significant distinction was observed between the groups regarding the site and the number of liver metastases (both P<0.05). (2) The median overall survival (OS) of the 282 patients was 22.7 months (95% CI: 17.8 to 27.6 months), with 1-year and 3-year OS rates were 65.4% and 35.6%, respectively. The 1-year OS rates for patients in the radical surgical group and palliative surgical group were 68.3% and 63.1%, while the corresponding 3-year OS rates were 42.2% and 29.9%, respectively. A comparison of OS between the two groups showed no statistically significant difference ( P=0.254). Further analysis indicated that patients undergoing palliative gastric cancer resection alone had a significantly worse prognosis compared to other surgical options ( HR=1.98, 95% CI: 1.21 to 3.24, P=0.006). (3) The size of the primary gastric tumor significantly influenced the patients′ prognosis ( HR=2.01, 95% CI: 1.45 to 2.79, P<0.01), with HR showing a progressively increasing trend as tumor size increased. (4) Subgroup analysis indicates that radical treatment may be more effective compared to palliative treatment in the following specific cases: well/moderately differentiated tumors ( HR=2.84, 95% CI 1.49 to 5.41, P=0.001), and patients with liver metastases located in the left lobe of the liver ( HR=2.06, 95% CI 1.19 to 3.57, P=0.010). Conclusions:In patients with IR-GCLM, radical surgery did not produce a significant improvement in the overall prognosis compared to palliative surgery. However, within specific patient subgroups (well/moderately differentiated tumors, and patients with liver metastases located in the left lobe of the liver), radical treatment can significantly improve prognosis compared to palliative approaches.

Objective:To examine the impact of varied surgical treatment strategies on the prognosis of patients with initial resectable gastric cancer liver metastases (IR-GCLM).Methods:This is a retrospective cohort study. Employing a retrospective cohort design, the study selected clinicopathological data from the national multi-center retrospective cohort study database, focusing on 282 patients with IR-GCLM who underwent surgical intervention between January 2010 and December 2019. There were 231 males and 51 males, aging ( M(IQR)) 61 (14) years (range: 27 to 80 years). These patients were stratified into radical and palliative treatment groups based on treatment decisions. Survival curves were generated using the Kaplan-Meier method and distinctions in survival rates were assessed using the Log-rank test. The Cox risk regression model evaluated HR for various factors, controlling for confounders through multivariate analysis to comprehensively evaluate the influence of surgery on the prognosis of IR-GCLM patients. A restricted cubic spline Cox proportional hazard model assessed and delineated intricate associations between measured variables and prognosis. At the same time, the X-tile served as an auxiliary tool to identify critical thresholds in the survival analysis for IR-GCLM patients. Subgroup analysis was then conducted to identify potential beneficiary populations in different surgical treatments. Results:(1) The radical group comprised 118 patients, all undergoing R0 resection or local physical therapy of primary and metastatic lesions. The palliative group comprised 164 patients, with 52 cases undergoing palliative resections for gastric primary tumors and liver metastases, 56 cases undergoing radical resections for gastric primary tumors only, 45 cases undergoing palliative resections for gastric primary tumors, and 11 cases receiving palliative treatments for liver metastases. A statistically significant distinction was observed between the groups regarding the site and the number of liver metastases (both P<0.05). (2) The median overall survival (OS) of the 282 patients was 22.7 months (95% CI: 17.8 to 27.6 months), with 1-year and 3-year OS rates were 65.4% and 35.6%, respectively. The 1-year OS rates for patients in the radical surgical group and palliative surgical group were 68.3% and 63.1%, while the corresponding 3-year OS rates were 42.2% and 29.9%, respectively. A comparison of OS between the two groups showed no statistically significant difference ( P=0.254). Further analysis indicated that patients undergoing palliative gastric cancer resection alone had a significantly worse prognosis compared to other surgical options ( HR=1.98, 95% CI: 1.21 to 3.24, P=0.006). (3) The size of the primary gastric tumor significantly influenced the patients′ prognosis ( HR=2.01, 95% CI: 1.45 to 2.79, P<0.01), with HR showing a progressively increasing trend as tumor size increased. (4) Subgroup analysis indicates that radical treatment may be more effective compared to palliative treatment in the following specific cases: well/moderately differentiated tumors ( HR=2.84, 95% CI 1.49 to 5.41, P=0.001), and patients with liver metastases located in the left lobe of the liver ( HR=2.06, 95% CI 1.19 to 3.57, P=0.010). Conclusions:In patients with IR-GCLM, radical surgery did not produce a significant improvement in the overall prognosis compared to palliative surgery. However, within specific patient subgroups (well/moderately differentiated tumors, and patients with liver metastases located in the left lobe of the liver), radical treatment can significantly improve prognosis compared to palliative approaches.

Objective:To investigate the prognosis of patients with initially resectable gastric cancer liver metastasis (GCLM) who were treated by different modalities, and analyze the influencing factors for prognosis of patients.Methods:The retrospective cohort study was conducted. The clinicopathological data of 327 patients with initially resectable GCLM who were included in the database of a nationwide multicenter retrospective cohort study on GCLM based on real-world data from January 2010 to December 2019 were collected. There were 267 males and 60 females, aged 61(54,68)years. According to the specific situations of patients, treatment modalities included radical surgery combined with systemic treatment, palliative surgery combined with systemic treatment, and systemic treatment alone. Observation indicators: (1) clinical characteristics of patients who were treated by different modalities; (2) prognostic outcomes of patients who were treated by different modalities; (3) analysis of influencing factors for prognosis of patients with initially resectable GCLM; (4) screening of potential beneficiaries in patients who were treated by radical surgery plus systemic treatment and patients who were treated by palliative surgery plus systemic treatment. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the independent sample t test. Measurement data with skewed distribution were represented as M( Q1, Q3), and comparison between groups was conducted using the rank sum test. Count data were described as absolute numbers or percentages, and comparison between groups was conducted using the chi-square test. The Kaplan-Meier method was used to calculate survival rate and draw survival curve, and Log-Rank test was used for survival analysis. Univariate and multivariate analyses were conducted using the COX proportional hazard regression model. The propensity score matching was employed by the 1:1 nearest neighbor matching method with a caliper value of 0.1. The forest plots were utilized to evaluate potential benefits of diverse surgical combined with systemic treatments within the population. Results:(1) Clinical characteristics of patients who were treated by different modalities. Of 327 patients, there were 118 cases undergoing radical surgery plus systemic treatment, 164 cases undergoing palliative surgery plus systemic treatment, and 45 cases undergoing systemic treatment alone. There were significant differences in smoking, drinking, site of primary gastric tumor, diameter of primary gastric tumor, site of liver metastasis, and metastatic interval among the three groups of patients ( P<0.05). (2) Prognostic outcomes of patients who were treated by different modalities. The median overall survival time of the 327 pati-ents was 19.9 months (95% confidence interval as 14.9-24.9 months), with 1-, 3-year overall survival rate of 61.3%, 32.7%, respectively. The 1-year overall survival rates of patients undergoing radical surgery plus systemic treatment, palliative surgery plus systemic treatment and systemic treatment alone were 68.3%, 63.1%, 30.6%, and the 3-year overall survival rates were 41.1%, 29.9%, 11.9%, showing a significant difference in overall survival rate among the three groups of patients ( χ2=19.46, P<0.05). Results of further analysis showed that there was a significant difference in overall survival rate between patients undergoing radical surgery plus systemic treatment and patients undergoing systemic treatment alone ( hazard ratio=0.40, 95% confidence interval as 0.26-0.61, P<0.05), between patients undergoing palliative surgery plus systemic treatment and patients under-going systemic treatment alone ( hazard ratio=0.47, 95% confidence interval as 0.32-0.71, P<0.05). (3) Analysis of influencing factors for prognosis of patients with initially resectable GCLM. Results of multivariate analysis showed that the larger primary gastric tumor, poorly differentiated tumor, larger liver metastasis, multiple hepatic metastases were independent risk factors for prognosis of patients with initially resectable GCLM ( hazard ratio=1.20, 1.70, 1.20, 2.06, 95% confidence interval as 1.14-1.27, 1.25-2.31, 1.04-1.42, 1.45-2.92, P<0.05) and immunotherapy or targeted therapy, the treatment modality of radical or palliative surgery plus systemic therapy were independent protective factors for prognosis of patients with initially resectable GCLM ( hazard ratio=0.60, 0.39, 0.46, 95% confidence interval as 0.42-0.87, 0.25-0.60, 0.30-0.70, P<0.05). (4) Screening of potentinal beneficiaries in patients who were treated by radical surgery plus systemic treatment and patients who were treated by palliative surgery plus systemic treatment. Results of forest plots analysis showed that for patients with high-moderate differentiated GCLM and patients with liver metastasis located in the left liver, the overall survival rate of patients undergoing radical surgery plus systemic treatment was better than patients undergoing palliative surgery plus systemic treatment ( hazard ratio=0.21, 0.42, 95% confidence interval as 0.09-0.48, 0.23-0.78, P<0.05). Conclusions:Compared to systemic therapy alone, both radical and palliative surgery plus systemic therapy can improve the pro-gnosis of patients with initially resectable GCLM. The larger primary gastric tumor, poorly differen-tiated tumor, larger liver metastasis, multiple hepatic metastases are independent risk factors for prognosis of patients with initial resectable GCLM and immunotherapy or targeted therapy, the treatment modality of radical or palliative surgery plus systemic therapy are independent protective factors for prognosis of patients with initially resectable GCLM.

Objective:To explore the medical reference values, distribution characteristics and influencing factors of serum iodine in adults with different thyroid health conditions, and to evaluate the importance of serum iodine in evaluating individual iodine nutrition.Methods:From February 2017 to November 2018, multi-stage stratified cluster sampling was used to select one community and one agricultural (fishing) village in the coastal Yingkou City and the inland areas of Shenyang City of Liaoning Province as survey sites. Cluster sampling of adults over 18 years old who had lived for five years were conducted with questionnaire survey, clinical physical examination and thyroid ultrasound examination. Fasting venous blood samples and one random urine sample were collected from all subjects for serum iodine, thyroid hormone, antibody and urine iodine detection. The 95% medical reference value of serum iodine was established by using the percentage quantile method, and the reference value, distribution characteristics and influencing factors of serum iodine in adults with different thyroid health status were analyzed. The diagnostic value of iodine nutritional indicators in thyroid diseases was evaluated by the receiver operating characteristic (ROC) curve.Results:A total of 2 931 adults were surveyed, with serum iodine levels of 62.1 (53.6, 72.2) μg/L, ranging from 5.6 to 642.3 μg/L; urine iodine was 167.6 (111.2, 244.2) μg/L, and the overall iodine level was at an appropriate level. A total of 1 089 patients with thyroid diseases were examined, with a detection rate of 37.2% (1 089/2 931); among them, there were 597 cases of thyroid nodules, 56 cases of endemic goiter, 42 cases of hypothyroidism, 161 cases of subclinical hypothyroidism, 27 cases of hyperthyroidism, 18 cases of subclinical hyperthyroidism, and 474 cases of autoimmune thyroid disease (AITD). There was a statistically significant difference in the detection of thyroid diseases among adults with different levels of serum iodine (χ 2 = 13.80, P < 0.05). The reference values of serum iodine in normal adults, hypothyroidism (without thyroid hormone intervention), hyperthyroidism (without anti thyroid hormone drug treatment), AITD, endemic goiter, and thyroid nodules were 37.2 - 103.0, 12.5 - 52.8, 49.9 - 163.1, 34.3 - 129.3, 27.3 - 92.8, and 37.9 - 119.5 μg/L, respectively. The ROC curve analysis results showed that the serum iodine area under curve(AUC) of patients with hyperthyroidism, subclinical hyperthyroidism, endemic goiter, thyroid nodules, and AITD were 0.94, 0.61, 0.55, 0.53, and 0.52, respectively. The results of univariate analysis showed that there were statistically significant differences in adult serum iodine levels among different positions, regions, age, education level, occupation, iodine intake, blood pressure, and body mass index ( P < 0.05). Conclusions:There are significant differences in serum iodine levels among adults with different thyroid health conditions, and evaluation standards and systems should be developed separately. Serum iodine is an important indicator for evaluating individual iodine nutrition.

Objective:To learn about the levels of serum iodine and thyroid function indicators in adults with normal thyroid function in Liaoning Province, to establish the medical reference value range of serum iodine, and to explore the relationship between serum iodine and thyroid function indicators.Methods:From February 2017 to December 2018, one subdistrict and one rural township were selected as the survey sites in the coastal area (Gaizhou City of Yingkou) and inland area (Kangping County of Shenyang) of Liaoning Province, respectively. Permanent residents aged 18 and older who have lived there for 5 years or more were selected as the survey subjects. Blood samples were collected to test the levels of serum iodine and thyroid function indicators [thyroid stimulating hormone (TSH), free triiodothyronine (FT 3), free thyroxine (FT 4), thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb)]. The percentile method was used to establish the 95% medical reference value range of serum iodine in adults with normal thyroid function, and Pearson correlation analysis was used to analyze the correlation between serum iodine and thyroid function indicators. Results:A total of 1 621 adults with normal thyroid function were examined, the median serum iodine was 62.0 μg/L, and the 95% medical reference value range was preliminarily determined as 37.0-103.0 μg/L. Among them, the medians serum iodine of males and females (826 and 795 cases) were 62.3 and 61.0 μg/L, respectively, and there was no significant difference between genders ( Z=- 1.26, P = 0.210). The medians serum iodine of adults in coastal and inland areas (827 and 794 cases) were 61.7 and 61.9 μg/L, respectively, and there was no significant difference between areas ( Z = - 0.16, P = 0.870). The medians serum iodine of adults aged 18 - 29, 30 - 39, 40 - 49, 50 - 59 and 60 - 80 (385, 392, 378, 253 and 213 cases) were 61.0, 61.0, 63.0, 65.0 and 62.0 μg/L, respectively, and the difference between ages was statistically significant ( H = 14.52, P = 0.006). Pearson correlation analysis showed that serum iodine was weakly correlated with the level of FT 4 ( r = 0.17, P < 0.001), but not with the levels of TSH, TPOAb and TgAb ( P > 0.05). Conclusions:This study has established the medical reference value range of serum iodine in adults with normal thyroid function in Liaoning Province. Serum iodine is not correlated with the levels of TSH, TPOAb and TgAb.

Objective:To understand the urinary iodine external quality control assessment results of county-level iodine deficiency disorders laboratories in Liaoning Province.Methods:The numbers of county-level iodine deficiency disorders laboratories which participated in the national urinary iodine external quality control assessment in Liaoning Province from 2016 to 2019 were 19, 33, 39 and 56, respectively. The urinary iodine external quality control assessment results were statistically analyzed with the Z score method (qualified: │Z│≤2; basically qualified: 2 <│Z│ < 3; unqualified: │Z│≥3). The percentage of laboratories participating in the assessment and the qualified rate were calculated.Results:From 2016 to 2019, the percentage of county-level iodine deficiency disorders laboratories in Liaoning Province that participated in the national urinary iodine external quality control assessment increased year by year, which were 19.79% (19/96), 34.38% (33/96), 40.63% (39/96) and 58.33% (56/96), respectively. The qualified rates were 89.47% (17/19), 84.85% (28/33), 100.00% (39/39) and 100.00% (56/56), respectively.Conclusion:From 2016 to 2019, the percentage and detection capacity of county-level iodine deficiency disorders laboratories in Liaoning Province that participated in the national urinary iodine external quality control assessment have been improved.

Objective To analyze the iodine nutritional status of children and pregnant women in Liaoning Province,and the iodine content of edible salt suitable for iodine nutrition level,to provide a basis for adjusting the suitable salt iodine content standard of key population.Methods In 2015-2018,a cross-sectional survey method was used to conduct iodine nutritional status surveys in counties (districts) within the jurisdiction of Liaoning Province.One township (community) was selected in each county (district)according to the east,west,south,north,and middle directions.Forty children aged 8-10 (age and gender distribution balanced) and 20 pregnant women were selected in each township (community),urine and household salt samples were collected from children and pregnant women,to test urine and salt iodine levels;and the water samples from all township (community) water supply plants in the province were collected for water iodine detection in 2017;and all respondents were calculated the dietary iodine intake.The multi-order linear curve was used to fit the salt iodine content suitable for children and pregnant women.Results A total of 1 549 townships (communities) were surveyed,including 1 125 centralized water supply townships (communities) with water iodine ＜ 40 μg/L;50 820 children aged 8-10 and 26 707 pregnant women were selected from the centralized water supply towns.The average iodine content of edible salt was 24.0 and 23.9 mg/kg,respectively.The median urinary iodine level of children was 168.5 μg/L,at the appropriate level of iodine;the median urinary iodine level of pregnant women was 137.8 μg/L,at the deficiency level of iodine.The average dietary intake of iodine in children was 228.4 μg/d,which was 3.51 times of the standard iodine requirement (EAR,65 μg/d) and 2.54 times of the recommended intake (RNI,90 μ g/d).The average dietary intake of iodine in pregnant women was 273.4 μg/d,which was 1.71 times of the EAR (160 μg/d) and 1.19 times of the RNI (230 μg/d),and 21.4％ (5 728/26 707) of pregnant women had lower iodine intake than RNI,the iodine intake was insufficient.After multi-level linear curve fitting combined with monitoring data,the iodine content range of edible salt in children's urine was suitable and the iodine intake in RNI-tolerable intake (UL,300 μg/d) was 13-25 mg/kg (20 mg/kg + 20％);the iodine content range of edible salt in pregnant women's urinary iodine was suitable and the iodine intake in RNI-UL (600 μg/d) is 25-37 mg/kg (31 mg/kg + 20％).Conclusions Under the current salt iodine content standard (25 mg/kg) in Liaoning Province,children's iodine nutrition is generally at the level of iodine appropriate;pregnant women's iodine nutrition is generally at the level of iodine deficiency.It is recommended that all regions should revise the iodine content standard for edible salt in due course in combination with the iodine nutritional status of key populations within the jurisdiction.

Objective Software Origin was used to evaluate urine iodine external quality control results in Liaoning Province in 2017,and to promote the application of software Origin in laboratory proficiency testing and to improve the urine iodine detection capability of laboratories in Liaoning Province.Methods In 2017,1 provincial-,14 municipal-and 33 county-level disease prevention and control institution laboratories in Liaoning Province were numbered,1-15:provincial and municipal levels,16-48:county-level.Software Origin 9.5 was used to produce the Z-ratio histogram,the deviation bar graph of repeated measurement results and the Youden plot of urine iodine external quality control results.When ｜Z｜ ≤2,it was satisfactory;when 2 ＜ ｜Z｜ ＜ 3,it indicated problems;when ｜Z｜ ≥3,it was not satisfactory.Based on ｜ Z｜ scores of laboratories,systematic errors and random errors were analyzed.Results Most laboratories had scores of ｜Z｜ ≤2,the results were satisfactory.Laboratory 36 had scores of ｜Z｜ ＞ 3,the result was not satisfactory,there were both systematic errors and random errors.The deviation bar graph of repeated measurement results showed that the precision of the high concentration test results in laboratory 21 was poor.Conclusions The software Origin is suitable to evaluate laboratory proficiency testing.The capacity of urine iodine detection in the county-level laboratories in Liaoning Province needs to be improved.Systematic errors and random errors still exist in individual laboratories.It is necessary to find the causes of errors,and strengthen laboratory internal quality control and improve the quality of the laboratory.