Using Bland-Altman plot-based harmonization algorithm to optimize the harmonization for immunoassays.

OBJECTIVES: Harmonization has been recommended by the International Organization for Standard (ISO) to achieve equivalent results across in vitro diagnostic measurement devices (IVD-MDs). We aim to evaluate the effectiveness of Bland-Altman plot-based harmonization algorithm (BA-BHA) created in this study and compare it with weighted Deming regression-based harmonization algorithm (WD-BHA) proposed in ISO 21151:2020. METHODS: Eighty patient sera were used as the harmonization reference material (HRM) to develop IVD-MD-specific harmonization algorithms. Another panel of 40 patient sera was used to validate the effectiveness of harmonization algorithms. We compared regression slopes, intercepts, Bland-Altman plot layouts, percent differences, limits of agreement (LoAs), between-method coefficients of variation (CV) before and after harmonization. RESULTS: After harmonization by WD-BHA, acceptable slopes and intercepts between measured values and HRM targets were observed in weighted Deming regression, but not in Passing-Bablok analysis. Mean differences were -5.5 to 5.0 % and differences at specific levels were -33.9 to 23.9 %. LoAs were -64.6 to 74.6 %. Between-method CV was 22.9 % (±12.9 %). However, after harmonization by BA-BHA, both weighted Deming and Passing-Bablok regressions equations presented harmonized results. Mean differences were -0.3 to 0.2 % and differences at specific levels were -1.1 to 1.6 %. LoAs were -23.3 to 23.2 %. Between-method CV was 8.4 % (±4.0 %). The data points were evenly distributed at both sides of the mean in Bland-Altman plots. CONCLUSIONS: The inequivalence of test results between different methods can be improved but unacceptable analytical differences at specific levels may be hidden in terms of an acceptable slope and intercept on WD-BHA. The new protocol BA-BHA may be a viable alternative to optimize the harmonization for immunoassays.

Longitudinal association of chronic diseases with depressive symptoms in middle-aged and older adults in China: Mediation by functional limitations, social interaction, and life satisfaction.

Background: Several previous studies have shown that the development of depression is often accompanied by chronic diseases; although closely related, the mechanism between them is not clear. Here we investigate the potential role of functional limitations, social interaction, and life satisfaction in the relationship between chronic diseases and depressive symptoms in middle-aged and older adults in China. Methods: We selected 2407 respondents aged ≥45 from the China Health and Retirement Longitudinal Study conducted in 2013, 2015, and 2018. We established panel data to estimate the longitudinal impact of chronic diseases on depressive symptoms and the mediating role of functional limitations, social interaction, and life satisfaction. Results: Chronic diseases were associated with more depressive symptoms. All of the mediating pathways examined passed functional limitations, and approximately 43.4% of the association between chronic diseases and depressive symptoms was explained by these three mediating variables. Conclusions: The impact of chronic diseases on depressive symptoms was primarily mediated by functional limitations, and the mediating role of social interaction and life satisfaction was also confirmed. Therefore, attention should be paid to reducing the level of functional limitation in middle-aged and older adults with chronic diseases and improving life satisfaction by increasing social opportunities to alleviate depressive symptoms in middle-aged and older adults.

Potential mechanistic roles of Interleukin-33 in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that occurs mainly in synovial joints, causing synovial inflammation and joint injury. If diagnosed and treated in time, the disease can be well controlled. However, in clinical practice, patients often fail to get timely and effective treatment due to misdiagnosis, missed diagnosis, and other reasons, resulting in deterioration of the condition and poor prognosis, seriously affecting the patient's quality of life. So far, the pathogenesis of RA is still unclear. In recent years, it has been found that the imbalance of cytokines plays a vital role in the occurrence and development of RA. Most RA-related cytokines are produced by immune cells, which bind to the specific receptors of effector cells through paracrine and autocrine pathways. The effect of cytokines on inflammation can be divided into pro-inflammatory and anti-inflammatory factors. When the impact of pro-inflammatory factors is more significant than anti-inflammatory factors, the condition of RA will be aggravated, resulting in more inflammatory severe reactions and immune disorders. Interleukin-33 (IL-33) is a new member of the interleukin-1(IL-1) family, and its receptor is suppression of tumorigenicity 2 (ST2). IL-33 plays a vital role in immune diseases such as RA by promoting a series of biochemical reactions in macrophages, mast cells, granulocytes, and other cells. This article aims to summarize the research progress of IL-33 in the pathogenesis of RA in recent years, discuss its role in the pathogenesis of RA, and provide new ideas for the prevention and treatment of RA in the future.

Development and application of a high accuracy method for measuring Pb in blood.

BACKGROUND: Lead (Pb) is an environmental pollutant, and human exposure is assessed by measuring blood Pb concentrations. Today, the use of Pb-based products is restricted, but the health effects of low Pb concentrations require investigation. For this, a high-accuracy method is needed. Here, we report a new inductively coupled plasma mass spectrometry (ICP-MS) method for quantifying Pb in blood. METHODS: Blood samples and calibrators were gravimetrically spiked with bismuth as an internal standard, digested with ultrapure nitric acid, and diluted 100 times. The calibrators were made from high-purity reference materials supplied by the National Institute of Standards and Technology, and the sample concentration was measured using the calibration bracketing method. The analytical performance and application of the new method were investigated. RESULTS: The method had good specificity and a negligible matrix effect. The intra- and inter-assay coefficients of variation (CVs) were <1.34 % and <1.88 %, respectively, and the total CV was <1.74 %. The range of recovery was 98.9 %-99.4 %. SRM955d, BCR-635, and BCR-636 were within the certified intervals, with mean relative bias values of 0.93 %, -0.13 %, and -0.56 %, respectively. The limit of quantification was 1.1 µg/l. The method was used to assign target values to external quality assessment samples and to assess routine methods, showing good results at high concentrations. However, at low concentrations, two laboratories did not pass. CONCLUSIONS: This ICP-MS method is a simple, accurate method and can be a candidate reference method for blood Pb measurement. But more research will be needed to verify this.

Global research trends in the subjective well-being of older adults from 2002 to 2021: A bibliometric analysis.

Purpose: This study aimed to explore current developments and trends in the field of subjective well-being (SWB) of older adults at a macro level and identify research hotspots. Methods: We included reviews and articles on the SWB of older adults in the Web of Science Core Collection published from 2002 to 2021. We used CiteSpace to draw a knowledge map of the authors, institutions, countries, references, and keywords for visual analysis and used Microsoft Excel tables to count basic information details. Results: A total of 354 papers were included, and the number of papers published over the past two decades showed a pattern of growth. The core force of publications was primarily attributed to studies conducted in Europe, North America, Asia, and Oceania, which have relatively major issues of aging and good economic strength. However, links between states, institutions, and authors were relatively weak. Cluster analysis showed that the research field could be divided into eight topics: the application of social psychology in the study of the SWB of older adults, aging in older adults, health condition of older adults, achieving successful aging, interventions for SWB, age differences in SWB research, an economic perspective of SWB research and social support for older adults. Current research frontiers are socioeconomic status, community, intervention, participation, adjustment, validation, and personality. Conclusion: The results of the present study provided a comprehensive picture in the research field of SWB of older adults. It showed that the mechanism, especially the bidirectional effect, between the SWB of older adults and its influencing factors is still worthy of further exploration. More research on evidence-based and intervention strategies should be conducted in the future.

Luteolin enhances the antitumor efficacy of oncolytic vaccinia virus that harbors IL-24 gene in liver cancer cells.

BACKGROUND: Interleukin 24 (IL-24) is an IL-10 family member and a secreted cytokine characterized by cancer-targeted toxicity and can activate apoptosis by sensitizing cancer cells to chemotherapy. Cytotoxic effects of luteolin on different types of cancer cells suppress their growth by acting on the components of the apoptosis signaling cascade. Therefore, our study aimed to prove whether oncolytic vaccinia virus (VV) that harbors IL-24 (VV-IL-24) combine with luteolin exerts a synergistic inhibitory effect in liver cancer cells. METHODS: Impacts on cell viability of VV-IL-24 and luteolin were assessed by MTT in various liver cancer cell lines. Then, liver cancer cell apoptosis was analyzed via flow cytometry and Western blotting. Besides, the MHCC97-H xenograft mouse model was employed as a means of assessing in vivo antitumor efficacy. RESULTS: MTT assay confirmed that the combination treatment decreased liver cancer cells viability to a greater degree than treatment with VV-IL-24 or luteolin alone. Flow cytometry and Western blot assay proved that VV-IL-24 plus luteolin induced more liver cancer cells apoptosis than single treatment. Furthermore, in the MHCC97-H xenograft model, 15 days of treatment with VV-IL-24 plus luteolin inhibited tumor growth significantly more than single treatment. CONCLUSION: These data confirm that the synergistic mechanism of VV-IL-24 and luteolin elicits a stronger tumor growth inhibition than any single therapy. Thus, the combination of VV-IL-24 and luteolin could provide the basis for preclinical research in the treatment of liver cancer.

Oncolytic Adenovirus CD55-Smad4 Suppresses Cell Proliferation, Metastasis, and Tumor Stemness in Colorectal Cancer by Regulating Wnt/ß-Catenin Signaling Pathway.

During the past few decades, colorectal cancer (CRC) incidence and mortality have significantly increased, and CRC has become the leading cause of cancer-related death worldwide. Thus, exploring novel effective therapies for CRC is imperative. In this study, we investigated the effect of oncolytic adenovirus CD55-Smad4 on CRC cell growth. Cell viability assay, animal experiments, flow cytometric analysis, cell migration, and invasion assays, and Western blotting were used to detect the proliferation, apoptosis, migration, and invasion of CRC cells. The oncolytic adenovirus CD55-Smad4 was successfully constructed and effectively suppressed CRC cell proliferation in vivo and in vitro. Notably, CD55-Smad4 activated the caspase signaling pathway, inducing the apoptosis of CRC cells. Additionally, the generated oncolytic adenovirus significantly suppressed migration and invasion of CRC cells by overexpressing Smad4 and inhibiting Wnt/ß-catenin/epithelial-mesenchymal transition (EMT) signaling pathway. Moreover, CRC cells treated with CD55-Smad4 formed less and smaller spheroid colonies in serum-free culture than cells in control groups, suggesting that CD55-Smad4 suppressed the stemness of CRC cells by inhibiting the Wnt/ß-catenin pathway. Together, the results of this study provide valuable information for the development of a novel strategy for cancer-targeting gene-virotherapy and provide a deeper understanding of the critical significance of Smad4 in gene therapy of CRC.

Doxorubicin hydrochloride enhanced antitumour effect of CEA-regulated oncolytic virotherapy in live cancer cells and a mouse model.

Oncolytic adenovirus (OA) has attracted increasing attention due to their specific proliferation in tumour cells and resulting in lysis of tumour cells. To further improve the antitumour effect of OA, in this study, we combined CD55-TRAIL-IETD-MnSOD (CD55-TMn), a CEA-controlled OA constructed previously, and chemotherapy to investigate their synergistic effect and possible mechanisms. MTT assay was performed to detect antitumour effects. Hoechst 33 342 and flow cytometric analysis were used to examine cell apoptosis. Western blotting was performed to examine cell pyroptosis and apoptosis mechanism. Animal experiment was used to detect antitumour effect of doxorubicin hydrochloride (Dox) combined with CD55-TMn in vivo. We firstly found that Dox promotes gene expression mediated by CEA-regulated OA and virus progeny replication by activating phosphorylation of Smad3, and Dox can enhance antitumour effect of CEA-regulated CD55-TMn by promoting cell apotopsis and cell pyroptosis. Thus, our results provide an experimental and theoretical basis on tumour therapy by combination treatment of the oncolytic virotherapy and chemotherapy and it is expected to become a novel strategy for liver cancer therapy.

Blood Collection Tubes and Storage Temperature Should Be Evaluated when Using the Siemens ADVIA Centaur XP for Measuring 25-Hydroxyvitamin D.

A significant bias was found when using the Siemens ADVIA Centaur XP system for measurement of 25-hydroxyvitamin D (25OHD) with VACUETTE® tubes with Serum Clot Activator and Gel. Here, we examined whether other commonly used tubes or temperatures affected 25OHD results obtained with the Siemens ADVIA Centaur XP system. Serum was collected into five types of vacuum blood collection tubes from three manufacturers, and 25OHD was analyzed using the Siemens ADVIA Centaur XP system and liquid chromatography tandem mass spectrometry (LC-MS/MS) immediately or after storage at 4°C or -80°C for 48 h. Significantly higher 25OHD values were found when using the Siemens ADVIA Centaur XP system with VACUETTE® tubes with serum clot activator and gel and VACUETTE® tubes with clot activator but no gel compared with VACUETTE® tubes with no additives. The 25OHD values in all of these tubes were not significantly different from those obtained by LC-MS/MS. Moreover, after storage at -80°C for 48 h, the values obtained in IMPROVEVACUTER® tubes with serum clot activator and gel significantly increased, with a mean bias of 74.6% compared with the values before storage, on analysis with the Siemens ADVIA Centaur XP system. VACUETTE® tubes containing additives significantly affect the accuracy of 25OHD results obtained using the Siemens ADVIA Centaur XP system. Additionally, the composition of serum collected in IMPROVEVACUTER® tubes was affected by freezing, resulting in different measurements when using the Siemens 25OHD assay platform.

Simultaneous Quantification of Serum Nonesterified and Esterified Fatty Acids as Potential Biomarkers to Differentiate Benign Lung Diseases from Lung Cancer.

In this study, we have employed graphene oxide as a matrix to simultaneously and directly quantify serum nonesterified and esterified fatty acids (FAs) using matrix-assisted laser/desorption ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS). Twelve serum nonesterified FAs combined with their individual esterified FAs (i.e., C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:2, C20:3, C20:4, C20:5, C22:5, and C22:6) were quantified based on their calibration curves with the correlation coefficients of >0.99, along with the analytical time of <1 min each sample. As a result, serum levels of twelve total FAs (TFAs) in 1440 serum samples from 487 healthy controls (HCs), 479 patients with benign lung diseases (BLDs) and 474 patients with lung cancer (LC) were determined. Statistical analysis indicated that significantly increased levels of C16:0, C16:1, C18:0, C18:1, C18:3, C20:3, and C22:6 and decreased levels of C20:5 were observed in LC patients compared with BLDs. Receiver operating characteristic (ROC) analysis revealed that panel a (C18:2, C20:3, C20:4, C20:5, C22:5, and C22:6), panel b (C18:0, C20:4, C20:5, and C22:6), and panel c (C16:1, C18:0, C18:1, C20:3, and C22:6) have exhibited good diagnostic ability to differentiate BLDs from LC relative to clinical uses of tumor markers (CEA and Cyfra 21-1).

Determination of 1,25-dihydroxyvitamin D2 and 1,25-dihydroxyvitamin D3 in human serum using liquid chromatography with tandem mass spectrometry.

Vitamin D plays important roles in skeletal metabolism and many other diseases, including chronic renal failure, hypoparathyroidism, sarcoidosis and rickets. 1α,25-dihydroxy vitamin D (1α,25(OH)2D), the active form of vitamin D, exhibits an extremely low serum concentration, which makes its quantification very challenging. High performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) is considered to be the "gold standard" for the determination of these chemicals, which are found in low concentrations in the serum, but conventionally, it needs tedious sample pretreatment procedures, such as solid phase extraction and derivatization. Herein, we describe a simple and rapid HPLC-MS/MS method for the simultaneous quantification of 1α,25-dihydroxy vitamin D3 (1α,25(OH)2D3) and 1α,25-dihydroxy vitamin D2 (1α,25(OH)2D2). The analytes were extracted from the matrix by liquid-liquid extraction, centrifuged to dryness and reconstituted with 75% methanol. Lithium acetate was employed to improve the ionization efficiency of 1α,25(OH)2D. The assay was sensitive with a low limit of quantitation of 10.0pg/mL for both 1α,25(OH)2D3 and 1α,25(OH)2D2 using a 0.5mL sample aliquot. Linearity was obtained over the range of 10.0pg/mL to 500pg/mL. Both the inter-assay and intra-assay precisions were <15%, and the analytical recoveries were within 100±5%. The performance evaluation of this assay demonstrated that it was a practical, sensitive and specific method for measuring the serum 1α,25(OH)2D3 and 1α,25(OH)2D2 concentrations.

Validation and comparison of a rapid liquid chromatography tandem mass spectrometry method for serum 25OHD with the efficiency of separating 3-epi 25OHD3.

OBJECTIVES: To develop a rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method with ability to separate 3-epi 25OHD3 (EPI-LC-MS/MS) from 25OHD3, and evaluate the effects of 3-epi 25OHD3 on routine LC-MS/MS that cannot separate 3-epi 25OHD3 (NEPI-LC-MS/MS). DESIGN AND METHODS: Performance of the newly built EPI-LC-MS/MS was validated, and 982 samples were analyzed and compared by the two methods. RESULTS: Both methods showed a linearity coefficient correlation exceeding 0.999 in the 6.25-500nmol/L range for 25OHD2 and 25OHD3. Moreover, they showed a between run coefficient variation (CV) and total CV of < 5% for 25OHD2 and 25OHD3. The results of the accuracy test showed that the bias was below 6.19% in the absence of 3-epi 25OHD3. Comparison of the 25OHD results obtained by the two methods for 982 patients (age 1-100years) revealed excellent clinical agreement (Cohen's kappa=0.875) and correlation (R2=0.973). Among the 982patients, only 73patients had 3-epi 25OHD3 (>6.25nmol/L); out of these 73patients, the 3-epi 25OHD3 level in 58patients was between 6.25 and 12.5nmol/L. In patients with <375nmol/L 25OHD (25OHD2+25OHD3), only 8 had 3-epi 25OHD3 levels exceeding 12.5nmol/L (range: 13.3 - 27.5nmol/L). Among samples containing 3-epi 25OHD3, only three were separated into different 25OHD-deficiency groups using the above methods. CONCLUSION: A rapid and precise EPI-LC-MS/MS method for measuring 25OHD with efficient separation of 3-epi 25OHD3 was developed. Our results showed that 3-epi 25OHD3 had little effect on the routinely used NEPI-LC-MS/MS.

25OHD analogues and vacuum blood collection tubes dramatically affect the accuracy of automated immunoassays.

Variations in vitamin D quantification methods are large, and influences of vitamin D analogues and blood collection methods have not been systematically examined. We evaluated the effects of vitamin D analogues 25OHD2 and 3-epi 25OHD3 and blood collection methods on vitamin D measurement, using five immunoassay systems and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum samples (332) were selected from routine vitamin D assay requests, including samples with or without 25OHD2 or 3-epi 25OHD3, and analysed using various immunoassay systems. In samples with no 25OHD2 or 3-epi 25OHD3, all immunoassays correlated well with LC-MS/MS. However, the Siemens system produced a large positive mean bias of 12.5 ng/mL and a poor Kappa value when using tubes with clot activator and gel separator. When 25OHD2 or 3-epi 25OHD3 was present, correlations and clinical agreement decreased for all immunoassays. Serum 25OHD in VACUETTE tubes with gel and clot activator, as measured by the Siemens system, produced significantly higher values than did samples collected in VACUETTE tubes with no additives. Bias decreased and clinical agreement improved significantly when using tubes with no additives. In conclusion, most automated immunoassays showed acceptable correlation and agreement with LC-MS/MS; however, 25OHD analogues and blood collection tubes dramatically affected accuracy.

Strong Negative Interference by Calcium Dobesilate in Sarcosine Oxidase Assays for Serum Creatinine Involving the Trinder Reaction.

The vasoprotective drug calcium dobesilate is known to interfere with creatinine (Cr) quantifications in sarcosine oxidase enzymatic (SOE) assays. The aim of this study was to investigate this interference in 8 different commercially available assays and to determine its clinical significance. In in vitro experiments, interference was evaluated at 3 Cr levels. For this, Cr was quantified by SOE assays in pooled serum supplemented with calcium dobesilate at final concentrations of 0, 2, 4, 8, 16, 32, and 64 µg/mL. Percent bias was calculated relative to the drug-free specimen. For in vivo analyses, changes in serum concentrations of Cr, cystatin C (CysC; a renal function marker), and calcium dobesilate were monitored in healthy participants of group I before and after oral calcium dobesilate administration. In addition, variations in interference were also examined among different SOE assays using serum obtained from healthy participants of group II. Lastly, Cr levels from the 10 patients treated with calcium dobesilate were measured using 4 SOE assays and liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) for comparison. Our in vitro analyses indicated that the presence of 8 µg/mL calcium dobesilate resulted in a -4.4% to -36.3% reduction in Cr serum concentration compared to drug-free serum for 8 SOE assays examined. In vivo, Cr values decreased relative to the baseline level with increasing drug concentration, with the lowest Cr levels obtained at 2 or 3 hours after drug administration in participants of group I. The observed Cr concentrations for participants in group II were reduced by -28.5% to -3.1% and -60.5% to -11.6% at 0 and 2 hours after administration related to baseline levels. The Cr values of 10 patients measured by Roche, Beckman, Maker, and Merit Choice SOE assays showed an average deviation of -20.0%, -22.4%, -14.2%, and -29.6%, respectively, compared to values obtained by LC-IDMS/MS. These results revealed a clinically significant negative interference with calcium dobesilate in all sarcosine oxidase-based Cr assays, but the degree of interference varied greatly among the assays examined. Thus, extra care should be taken in evaluating Cr quantification obtained by SOE assays in patients undergoing calcium dobesilate therapy.

Values of iodine metabolism biomarkers in assessing the iodine nutrition status in surgically treated patients with thyroid disease.

OBJECTIVE: To assess the clinical application value of iodine metabolism biomarkers in assessing iodine nutrition status in surgically treated patients with thyroid disease. METHODS: Blood,morning urine and 24-hour urine samples were collected in 31 healthy volunteers and in 30 surgically treated patients with thyroid disease before and after surgery. Iodine concentration was analyzed by inductively coupled plasma mass spectrometry. The iodine metabolism biomarkers including serum iodine (SI), morning urine iodine(UI), morning urine iodine/urine creatinine ratio (UI/UCr), 24-hour urine iodine (24 h UI), and 24-hour urine iodine excretion (24 h UIE) were evaluated in these two groups. In addition, the validation coincidence rate of iodine metabolism biomarkers in healthy volunteers to different reference ranges including World Health Organization, Mayo Clinic, and Quest Diagnostics were calculated. RESULTS: The UI/UCr ratio of pre-operative thyroid disease patients was significantly lower than that of healthy volunteers (P<0.05), while the other biomarkers showed no significant differences (all P>0.05) between these two groups. The SI, UI ,and 24 h UI in postoperative thyroid disease patients were significantly higher than those of the pre-operative patients (all P<0.05). Though the medians of all biomarkers in healthy volunteers were within the reference ranges,only the validation coincidence rates of SI, UI, and UI/UCr in the 41-70-year populations were over than 90% according to Mayo Clinic; furthermore, the area under the receiver operating characteristic curve about UI/UCr ratio (0.737) was the biggest within the iodine metabolism biomarkers. CONCLUSION: The UI/UCr ratio may be used for iodine nutrition evaluation in surgically treated patients with thyroid disease.

The high prevalence of hypovitaminosis D in China: a multicenter vitamin D status survey.

Vitamin D deficiency, which is usually detected by using immunoassays or the more reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) methods, has recently been considered a public health problem worldwide. However, the vitamin D status in Chinese populations, as measured using the LC-MS/MS method, is not available. The objective of this multicenter study was to determine the vitamin D status and prevalence of vitamin D deficiency by using a reliable method in 5 large cities in China. From May 1 to September 31, 2013, we conducted a multicenter study on 2173 apparently healthy adults who were recruited from 5 Chinese cities. The 25-hydroxyvitamin D 25OHD2 and 25OHD3 levels were measured using the LC-MS/MS method. Intact parathyroid hormone (iPTH), calcium, phosphorus, and alkaline phosphate levels were also measured using an automatic analyzer. The mean 25OHD level of all participants was 19.4 ±â€Š6.4 ng/mL (2.5-97.5%: 7.9-32.6 ng/mL), and only 109 (5.0%) participants had a 25OHD2 level >2.5 ng/mL (maximum, 22.4 ng/mL). In this study, the prevalence of severe vitamin D deficiency (<10 ng/mL), vitamin D deficiency (10-20 ng/mL), vitamin D insufficiency (20-30 ng/mL), and vitamin D sufficiency (>30 ng/mL) was 5.9%, 50.0%, 38.7%, and 5.4%, respectively. Women had a significant higher rate of deficiency than men (66.3% vs 45.3%, P < 0.01). Participants aged 18 to 39 years had a lower 25OHD level than elderly individuals (>59 years). Lifestyle may influence the 25OHD level more than the latitude, with participants in Dalian having the highest 25OHD level and the lowest deficiency rate. The serum iPTH level showed a significant negative correlation with the 25OHD level (r = -0.23, P < 0.01) after correcting for age and sex. In conclusion, the present study evaluated the vitamin D status using a reliable method, and our results indicate that vitamin D deficiency is prevalent among all age groups in China, especially among younger adults. We also observed significant differences in the 25OHD levels according to sex, age, and region among apparently healthy individuals.