Commutability is where the measurement response for a reference material (RM) is the same as for an individual patient sample with the same concentration of analyte measured using two or more measurement systems. Assessment of commutability is essential when the RM is used in a calibration hierarchy or to ensure that clinical measurements are comparable across different measurement procedures and at different times. The commutability of three new Standard Reference Materials(®) (SRMs) for determining serum total 25-hydroxyvitamin D [25(OH)D], defined as the sum of 25-hydroxyvitamin D(2) [25(OH)D(2)] and 25-hydroxyvitamin D(3) [25(OH)D(3)], was assessed through an interlaboratory study. The following SRMs were assessed: (1) SRM 2969 Vitamin D Metabolites in Frozen Human Serum (Total 25-Hydroxyvitamin D Low Level), (2) SRM 2970 Vitamin D Metabolites in Frozen Human Serum (25-Hydroxyvitamin D(2) High Level), and (3) SRM 1949 Frozen Human Prenatal Serum. These SRMs represent three clinically relevant situations including (1) low levels of total 25(OH)D, (2) high level of 25(OH)D(2), and (3) 25(OH)D levels in nonpregnant women and women during each of the three trimesters of pregnancy with changing concentrations of vitamin D-binding protein (VDBP). Twelve laboratories using 17 different ligand binding assays and eight laboratories using nine commercial and custom liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays provided results in this study. Commutability of the SRMs with patient samples was assessed using the Clinical and Laboratory Standards Institute (CLSI) approach based on 95% prediction intervals or a pre-set commutability criterion and the recently introduced International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) approach based on differences in bias for the clinical and reference material samples using a commutability criterion of 8.8%. All three SRMs were deemed as commutable with all LC-MS/MS assays using both CLSI and IFCC approaches. SRM 2969 and SRM 2970 were deemed noncommutable for three and seven different ligand binding assays, respectively, when using the IFCC approach. Except for two assays, one or more of the three pregnancy levels of SRM 1949 were deemed noncommutable or inconclusive using different ligand binding assays and the commutability criterion of 8.8%. Overall, a noncommutable assessment for ligand binding assays is determined for these SRMs primarily due to a lack of assay selectivity related to 25(OH)D(2) or an increasing VDBP in pregnancy trimester materials rather than the quality of the SRMs. With results from 17 different ligand binding and nine LC-MS/MS assays, this study provides valuable knowledge for clinical laboratories to inform SRM selection when assessing 25(OH)D status in patient populations, particularly in subpopulations with low levels of 25(OH)D, high levels of 25(OH)D(2), women only, or women who are pregnant.

Racism is a fundamental determinant of health inequities among racial and ethnic groups and is understudied among adolescents. In 2023, the national Youth Risk Behavior Survey questionnaire included an item assessing experiences of racism in the school setting among students in grades 9-12 in the United States. This report estimates the prevalence of students who reported ever having experienced racism in school and compares prevalence by racial and ethnic groups. For each racial and ethnic group, prevalence differences and prevalence ratios were estimated comparing the prevalence of indicators of poor mental health, suicide risk, and substance use among students who reported that they have ever versus never experienced racism in school. In 2023, approximately one in three high school students (31.5%) said that they had ever experienced racism in school. Reported experiences of racism were most prevalent among Asian (56.9%), multiracial (48.8%), and Black or African American (Black) (45.9%) students and least prevalent among White students (17.3%). Black and Hispanic or Latino (Hispanic) students who reported experiencing racism had a higher prevalence of all health risk behaviors and experiences investigated, including indicators of poor mental health, suicide risk, and substance use compared with students of their racial and ethnic group who reported never experiencing racism. Many of these associations were also found among multiracial and White students. Student reports of racism were associated with indicators of mental health and suicide risk among American Indian or Alaska Native (AI/AN) and Asian students. Among students of color, including AI/AN, Asian, Black, Hispanic, and multiracial students, the prevalence of seriously considering and attempting suicide was more than two times higher among students who ever compared with never experienced racism. These findings demonstrate that racism in the school setting is experienced by high school students attending public and private schools and continues to disproportionately affect students of color. Students who reported experiencing racism had a higher prevalence of indicators of poor mental health, suicide risk, and substance use. Schools can incorporate policies and practices to prevent unfair treatment on the basis of race and ethnicity and offer resources to help students cope with these experiences.

Parents have an important role in the promotion of healthy adolescent behaviors that can influence positive developmental trajectories and health outcomes. Parental monitoring is a central component of the parent-child relationship with the potential to reduce adolescent risk behaviors. Data from CDC's 2021 nationally representative Youth Risk Behavior Survey were used to describe the prevalence of parental monitoring reported by U.S. high school students and examine associations between parental monitoring and adolescent behaviors and experiences. Behaviors and experiences included sexual behaviors, substance use, violence, and indicators of poor mental health. This report marks the first national assessment of parental monitoring among U.S. high school students. Point prevalence estimates and corresponding 95% CIs were generated in the bivariate analyses between parental monitoring and the outcomes, stratified by demographic characteristics (sex, race and ethnicity, sexual identity, and grade). Multivariable logistic regression analyses were conducted to estimate the main effects of parental monitoring (categorized as high = always or most of the time and low = never, rarely, or sometimes) for each outcome, controlling for all demographics. Overall, 86.4% of students reported that their parents or other adults in their family know where they are going or with whom they will be all or most of the time. Reports of high parental monitoring were protective for all risk behaviors and experiences, with models controlling for sex, race and ethnicity, sexual identity, and grade. Results highlight the need for public health professionals who develop public health interventions and programs to conduct further research on the relation between parental monitoring and student health outcomes.

BACKGROUND: There are notable disparities by race/ethnicity in the sexual health of US adolescents and young adults. Our objective was to examine change over time in racial-ethnic disparities in sexual behaviours among US high school students. METHODS: Data were analysed from six biennial cycles of the national Youth Risk Behavior Survey (2009-19), conducted among cross-sectional, nationally representative samples of 9th-12th grade students. Data were collected via self-administered questionnaires. Multivariable logistic regression models tested for linear trends by race/ethnicity (White, Black, Hispanic) and differences in these trends in: ever had sex, current sexual activity, having four or more lifetime sexual partners, and condomless sex. Prevalence ratios and risk differences by race/ethnicity for each cycle were used to calculate average percent change in the estimates to determine if health disparities changed over time. RESULTS: During 2009-19, prevalence estimates for ever had sex, current sexual activity, and having four or more lifetime sexual partners decreased overall and across all racial-ethnic groups. For condomless sex, prevalence estimates increased over time overall (38.9-45.7%) and for Black (37.6-51.8%) and White (36.7-44.2%) students, but not Hispanic (45.1-43.8%) students. Significant differences in trends by race/ethnicity were observed for all variables. Data suggest that racial-ethnic health disparities for sexual behaviours decreased over time, except for condomless sex. CONCLUSIONS: Although racial-ethnic gaps in sexual behaviours may be shrinking for many behaviours, work is still needed to achieve health equity in risks associated with HIV/AIDS, sexually transmitted infections, and pregnancy.

During events like the COVID-19 pandemic or a disaster, researchers may need to switch from collecting biological samples to personal exposure samplers that are easy and safe to transport and wear, such as silicone wristbands. Previous studies have demonstrated significant correlations between urine biomarker concentrations and chemical levels in wristbands. We build upon those studies and use a novel combination of descriptive statistics and supervised statistical learning to evaluate the relationship between polycyclic aromatic hydrocarbon (PAH) concentrations in silicone wristbands and hydroxy-PAH (OH-PAH) concentrations in urine. In New York City, 109 participants in a longitudinal birth cohort wore one wristband for 48 h and provided a spot urine sample at the end of the 48-hour period during their third trimester of pregnancy. We compared four PAHs with the corresponding seven OH-PAHs using descriptive statistics, a linear regression model, and a linear discriminant analysis model. Five of the seven PAH and OH-PAH pairs had significant correlations (Pearson's r = 0.35-0.64, p ≤ 0.003) and significant chi-square tests of independence for exposure categories (p ≤ 0.009). For these five comparisons, the observed PAH or OH-PAH concentration could predict the other concentration within a factor of 1.47 for 50-80% of the measurements (depending on the pair). Prediction accuracies for high exposure categories were at least 1.5 times higher compared to accuracies based on random chance. These results demonstrate that wristbands and urine provide similar PAH exposure assessment information, which is critical for environmental health researchers looking for the flexibility to switch between biological sample and wristband collection.

PURPOSE: This study examined associations between student sexual behaviors and both school-level socioeconomic status and metropolitan status. METHODS: National Youth Risk Behavior Survey data from 2017 (N = 14,765, response rate = 60%) and 2019 (N = 13,677, 60%) were combined. School-level socioeconomic status (low-, mid-, and high-poverty based on the percentage of students eligible for free or reduced-price meals) and metropolitan status (urban, suburban/town, or rural) were identified for students attending public high schools. Sexual behaviors included currently sexually active, four or more lifetime sexual partners, condom use during the last sexual intercourse, hormonal birth control use during the last sexual intercourse, condom and hormonal birth control use during the last sexual intercourse, and drank alcohol or used drugs before the last sexual intercourse. Adjusted prevalence ratios were calculated using logistic regression models, controlling for sex, race/ethnicity, and grade. RESULTS: Compared to students attending low-poverty schools, high-poverty school students were significantly more likely to be currently sexually active (adjusted prevalence ratio = 1.4 [95% confidence interval = 1.1-1.8]) and have four or more lifetime sexual partners (1.6 [1.0-2.5]), but were significantly less likely to have drank alcohol or used drugs before the last sexual intercourse (.7 [.5-.9]) and have used hormonal birth control during the last sexual intercourse (.7 [.6-1.0]). Compared to students attending rural schools, urban school students were significantly less likely to be currently sexually active (.8 [.7-.9]) and have four or more lifetime sexual partners (.7 [.5-.9]). CONCLUSIONS: School-level socioeconomic status and metropolitan status were associated with differential risk in sexual behaviors.

Vitamin D, an important hormone with a central role in calcium and phosphate homeostasis, is required for bone and muscle development as well as preservation of musculoskeletal function. The most abundant vitamin D metabolite is 25-hydroxyvitamin D [25(OH)D], which is currently considered the best marker to evaluate overall vitamin D status. 25(OH)D is therefore the most commonly measured metabolite in clinical practice. However, several other metabolites, although not broadly measured, are useful in certain clinical situations. Vitamin D and all its metabolites are circulating in blood bound to vitamin D binding protein, (VDBP). This highly polymorphic protein is not only the major transport protein which, along with albumin, binds over 99% of the circulating vitamin D metabolites, but also participates in the transport of the 25(OH)D into the cell via a megalin/cubilin complex. The accurate measurement of 25(OH)D has proved a difficult task. Although a reference method and standardization program are available for 25(OH)D, the other vitamin D metabolites still lack this. Interpretation of results, creation of clinical supplementation, and generation of therapeutic guidelines require not only accurate measurements of vitamin D metabolites, but also the accurate measurements of several other "molecules" related with bone metabolism. IFCC understood this priority and a committee has been established with the task to support and continue the standardization processes of vitamin D metabolites along with other bone-related biomarkers. In this review, we present the position of this IFCC Committee on Bone Metabolism on the latest developments concerning the measurement and standardization of vitamin D metabolites and its binding protein, as well as clinical indications for their measurement and interpretation of the results.

Currently the 25-hydroxy vitamin D (25(OH)D) concentration is thought to be the best estimate of the vitamin D status of an individual. Unfortunately, its measurement remains complex, despite recent technological advances. We evaluated the biological variation (BV) of 25(OH)D in order to set analytical performance specifications (APS) for measurement uncertainty (MU). Six European laboratories recruited 91 healthy participants. The 25(OH)D concentrations in K(3)-EDTA plasma were examined weekly for up to 10 weeks in duplicate on a Lumipulse G1200 (Fujirebio, Tokyo, Japan). The linear regression of the mean 25(OH)D concentrations at each blood collection showed that participants were not in a steady state. The dissection of the 10-sample collection into two subsets, namely collections 1-5 and 6-10, did not allow for correction of the lack of homogeneity: estimates of the within-subject BV ranged from 5.8% to 7.1% and the between-subject BV ranged from 25.0% to 39.2%. Methods that would differentiate a difference induced by 25(OH)D supplementation at p < 0.05 should have MU < 13.6%, while at p < 0.01, the MU should be <9.6%. The development of APS using BV assumes a steady state of patients. The findings in this study suggest that patients are not in steady state. Therefore, APS that are based on MU appear to be more appropriate.

Parathyroid hormone (PTH) determination is of greatest importance for patients suffering from parathyroid gland disorders and for the follow-up of bone turnover in patients suffering from chronic kidney disease (CKD). Two generations of PTH assays are simultaneously present on the market for PTH quantification. As these assays are not yet standardized, this results in a significant level of confusion in the care of CKD patients. One key objective of the IFCC Committee for Bone Metabolism is to improve this situation. In this position paper, we will highlight the current state of PTH testing and propose a pathway to ultimately overcome issues resulting from PTH assay variability.

Procollagen type I N-propeptide (PINP) and the C-terminal telopeptide of type I collagen (β-CTX) in blood have been designated as reference bone turnover markers in osteoporosis by the International Osteoporosis Foundation (IOF) and International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). The IFCC Committee on Bone Metabolism (C-BM) has examined current commercial assays and performed a multicentre study to examine the agreement between assays for PINP and β-CTX in serum and plasma. The results of these studies will inform our work towards the harmonization of PINP assays and the standardization of β-CTX assays in blood, with the development of common calibrators and reference measurement procedures in collaboration with the reagent manufacturing industry. Successful achievement of these goals will help develop universally acceptable practice guidelines for the management of osteoporosis with the inclusion of common reference intervals and treatment targets for PINP and β-CTX.

International Federation of Clinical Chemistry and Laboratory Medicine and The International Osteoporosis Foundation Joint Committee on Bone Metabolism believes that the harmonization of PINP assays is an achievable and practical goal. INTRODUCTION: In order to examine the agreement between current commercial assays, a multi-center study was performed for PINP in serum and plasma. METHODS: The automated methods for PINP (Roche Cobas and IDS iSYS) gave similar results. A significant proportional bias was observed between the two automated assays and the Orion radioimmunoassay (RIA) for PINP. RESULTS: Results from other published studies comparing PINP values among these three assays broadly support our findings. Taken together, these results confirm that harmonized PINP measurements exist between the two automated assays (Roche Cobas and IDS iSYS) when the eGFR is > 30 mL/min/1.73m(2), but a significant bias exists between the Orion RIA and the two automated assays. CONCLUSION: Therefore, in subjects with normal renal function, PINP results reported by the Roche Cobas and IDS iSYS assays are similar and may be used interchangeably, and similar reference intervals and treatment targets could be applied for the two automated assays. Harmonization between the automated assays and the RIA is potentially possible with the use of common calibrators and the development of a reference method for PINP. This should also help ensure that any new commercial assay developed in the future will attain similar results. IOF and IFCC are committed to working together towards this goal with the cooperation of the reagent manufacturing industry.

Meg: I'm in Angola right now where the country is seeing the largest yellow fever outbreak since 1986 and the number of malaria cases appear to be higher than normal this time of the year. I was at dinner the other night among seasoned travelers and I was struck by how different our attitudes were about malaria prophylaxis. | Paul: I hope you're taking yours. | Meg: Of course! I'm religiously taking mine every morning. Some of us are meticulous about not missing a dose whereas others seem to have a more cavalier attitude about it. They don't seem to be aware of the potential serious consequences of a malaria infection. And I was surprised by the spectrum of side effects they say they've experienced in the past with the different prophylaxis options. A lot of GI upset, and of course, the most common – weird, vivid dreams with mefloquine. But I've also heard people tell me about neuropsychiatric side effects even on other antimalarials.