Mineral Intake Ratios Are a Weak but Significant Factor in Blood Pressure Variability in US Adults.

Background: Hypertension contributes substantially to chronic disease and mortality. Mineral intakes can modify blood pressure. Objective: Individual minerals and their intake ratios in US adults and their association with blood pressure were examined. Methods: Regression models were used to examine the associations of sodium, potassium, and calcium intakes and their ratios from food and supplements with blood pressure in 8777 US adults without impaired renal function from the 2011-2014 NHANES. We evaluated men (n = 4395) and women (n = 4382) separately. Models for predicting blood pressure were developed using age, blood pressure medication, race, body mass index (BMI), and smoking as explanatory variables. Results: Few adults met the recommended intake ratios for sodium:potassium (1.2% and 1.5%), sodium:calcium (12.8% and 17.67%), and sodium:magnesium (13.7% and 7.3%) for men and women, respectively. Approximately half of adults (55.2% of men and 54.8% of women) met calcium:magnesium intake ratio recommendations. In our regression models, the factors that explained the largest amount of variability in blood pressure were age, blood pressure medication, race/ethnicity, BMI, and smoking status. Together, these factors explained 31% and 15% of the variability in systolic blood pressure in women and men, respectively. The sodium:potassium (men and women), sodium:magnesium (women), and sodium:calcium (men) intake ratios were positively associated with systolic blood pressure, whereas calcium intake was inversely associated with systolic blood pressure in men only. When mineral intake ratios were added individually to our regression models, they improved the percentage of variability in blood pressure explained by the model by 0.13-0.21%. Conclusions: Strategies to lower blood pressure are needed. Lower sodium:potassium intake ratios provide a small benefit for protection against hypertension in US adults.

Soluble Corn Fiber Increases Calcium Absorption Associated with Shifts in the Gut Microbiome: A Randomized Dose-Response Trial in Free-Living Pubertal Females.

BACKGROUND: Soluble corn fiber (SCF; 12 g fiber/d) is shown to increase calcium absorption efficiency, associated with shifts in the gut microbiota in adolescent males and females who participated in a controlled feeding study. OBJECTIVE: We evaluated the dose response of 0, 10, and 20 g fiber/d delivered by PROMITOR SCF 85 (85% fiber) on calcium absorption, biochemical bone properties, and the fecal microbiome in free-living adolescents. METHODS: Healthy adolescent females (n = 28; aged 11-14 y) randomly assigned into a 3-phase, double-blind, crossover study consumed SCF for 4 wk at each dose (0, 10, and 20 g fiber/d from SCF) alongside their habitual diet and were followed by 3-d clinical visits and 3-wk washout periods. Stable isotope ((44)Ca and (43)Ca) enrichment in pooled urine was measured by inductively coupled plasma mass spectrometry. Fecal microbial community composition was assessed by high-throughput sequencing (Illumina) of polymerase chain reaction-amplified 16S rRNA genes. Mixed model ANOVA and Friedman analysis were used to determine effects of SCF on calcium absorption and to compare mean microbial proportions, respectively. RESULTS: Calcium absorption increased significantly with 10 (13.3% ± 5.3%; P = 0.042) and 20 g fiber/d (12.9% ± 3.6%; P = 0.026) from SCF relative to control. Significant differences in fecal microbial community diversity were found after consuming SCF (operational taxonomic unit measures of 601.4 ± 83.5, 634.5 ± 83.8, and 649.6 ± 75.5 for 0, 10, and 20 g fiber/d, respectively; P < 0.05). Proportions of the genus Parabacteroides significantly increased with SCF dose (1.1% ± 0.8%, 2.1% ± 1.6%, and 3.0% ± 2.0% for 0, 10, and 20 g fiber/d from SCF, respectively; P < 0.05). Increases in calcium absorption positively correlated with increases in Clostridium (r = 0.44, P = 0.023) and unclassified Clostridiaceae (r = 0.40, P = 0.040). CONCLUSIONS: SCF, a nondigestible carbohydrate, increased calcium absorption in free-living adolescent females. Two groups of bacteria may be involved, one directly fermenting SCF and the second fermenting SCF metabolites further, thereby promoting increased calcium absorption. This trial was registered at clinicaltrials.gov as NCT01660503.

Dietary calcium requirements do not differ between Mexican-American boys and girls.

Mexican Americans are an understudied ethnic group for determinants of bone health, although the risk of age-related osteoporosis is high in this rapidly growing sector of the U.S. population. Thus, the objective of the present study was to establish the dietary calcium requirements for bone health in Mexican-American adolescents by measuring calcium retention calculated from balance in response to a range of dietary calcium intakes and to determine predictors of skeletal calcium retention. Adolescents aged 12-15 y were studied twice on paired calcium intakes ranging from 600 to 2300 mg/d using randomized-order, crossover 3-wk balance studies. Skeletal calcium retention was calculated as dietary calcium intake minus calcium excreted in feces and urine over the last 2 wk of balance. A linear model was developed to explain the variation in calcium retention. Boys (n = 20) were taller and had higher lean mass, usual dietary calcium intake, bone mineral content, and serum alkaline phosphatase compared with girls, whereas girls (n = 20) had higher Tanner scores and greater fat mass. Calcium retention increased with calcium intake (P < 0.0001) and did not differ by sex (P = 0.66). In boys and girls considered together, calcium intake explained 33% of the variation in calcium retention. Serum alkaline phosphatase explained an additional 11% of the variation in calcium retention. Other variables measured, including the urine N-telopeptide of type I collagen/creatinine ratio, Tanner score, serum parathyroid hormone and 25-hydroxyvitamin D, weight, height, and body mass index, did not contribute to the variance in calcium retention. In adolescence, calcium retention in both Mexican-American boys and girls was higher than determined previously in adolescent nonHispanic white girls. This trial was registered at clinicaltrials.gov as NCT01277185.

Soluble maize fibre affects short-term calcium absorption in adolescent boys and girls: a randomised controlled trial using dual stable isotopic tracers.

Soluble maize fibre (SCF) has been found to significantly improve bone mineral density and strength in growing rats compared with several other novel prebiotic fibres. The objective of the present study was to investigate the effect of SCF on Ca absorption and retention in pubertal children by studying the potential absorption mechanisms of the intestinal microbiota. A total of twenty-four adolescent boys and girls (12-15 years) participated in two 3-week metabolic balance studies testing 0 g/d SCF (control (CON) treatment) and 12 g/d SCF (SCF treatment) in a random order by inclusion in a low-Ca diet (600 mg/d). Fractional Ca absorption was measured at the end of the two intervention periods using a dual-stable isotope method. Diet composites and faecal and urine samples were collected daily and analysed for Ca content. Ca retention was calculated as dietary Ca intake minus Ca excretion in faeces and urine over the last 2 weeks. Microbial community composition in the faecal samples collected at the beginning and end of each session was determined by 454 pyrosequencing of the PCR-amplified 16S ribosomal RNA gene. Fractional Ca absorption was 12 % higher (41 mg/d) after the SCF treatment compared with that after the CON treatment (0·664 (sd 0·129) and 0·595 (sd 0·142), respectively; P= 0·02), but Ca retention was unaffected. The average proportion of bacteria of the phylum Bacteroidetes was significantly greater in the participants after the SCF treatment than after the CON treatment. These results suggest that moderate daily intake of SCF, a well-tolerated prebiotic fibre, increases short-term Ca absorption in adolescents consuming less than the recommended amounts of Ca.

Current estimate of Down Syndrome population prevalence in the United States.

OBJECTIVE: To calculate a reliable estimate of the population prevalence of Down syndrome in the US. STUDY DESIGN: The annual number of births of infants with Down syndrome were estimated by applying published birth prevalence rates of Down syndrome by maternal age to US data from the Centers for Disease Control and Prevention for the years for which births by maternal age were available (1940-2008). Death certificate data for persons with Down syndrome were available for the years 1968-2007. We estimated the number of people with Down syndrome on January 1, 2008, using a life table approach based on proportions of deaths by age. Monte Carlo sampling was used to create 90% uncertainty intervals (UIs) for our estimates. RESULTS: We estimated the January 1, 2008, population prevalence of Down syndrome as approximately 250700 (90% UI, 185900-321700) based on proportions of deaths by age from the most recent 2 years (2006-2007) of death certificate data. This estimate corresponds to a prevalence of 8.27 people with Down syndrome per 10000 population (90% UI, 6.14-10.62). CONCLUSION: Our estimate of Down syndrome prevalence is roughly 25%-40% lower than estimates based solely on current birth prevalence. The results presented here can be considered a starting point for facilitating policy and services planning for persons with Down syndrome.

Galacto-oligosaccharides increase calcium absorption and gut bifidobacteria in young girls: a double-blind cross-over trial.

Adolescence is a time for rapid growth that represents an opportunity to influence peak bone mass. Prebiotic agents, such as galacto-oligosaccharides (GOS), increase Ca absorption in animal models and postmenopausal women. The objectives of the present study were to investigate the dose-response relationship of GOS supplementation on Ca absorption during growth and to assess changes in colonic microbiota to better understand the mechanism by which GOS is acting. A total of thirty-one healthy adolescent girls aged 10-13 years consumed smoothie drinks twice daily with 0, 2·5 or 5 g GOS for three 3-week periods in a random order. Fractional Ca absorption was determined from urinary Ca excretion over 48 h at the end of each 3-week period using a dual stable isotope method. Faecal microbiota and bifidobacteria were assessed by PCR-denaturing gradient gel electrophoresis and quantitative PCR. Fractional Ca absorption after the 48 h treatment with control, 5 and 10 g GOS/d was 0·393 (SD 0·092), 0·444 (SD 0·086) and 0·419 (SD 0·099), respectively. Significant improvements in Ca absorption were seen with both low and high doses of GOS compared with the control (P,0·02), but itwas not a dose-response relationship. The increase in absorption was greatest in the urine collected after 24 h, which is consistent with lower gut absorption. Faecal bifidobacteria increased (control 10·89 (SD 13·86), 5 g GOS 22·80 (SD 15·74) and 10 g GOS 11·54 (SD 14·20)) with the GOS treatment (P,0·03). The results suggest that daily consumption of 5 g GOS increases Ca absorption, which may be mediated by the gut microbiota, specifically bifidobacteria.

Moderate consumption of freeze-dried blueberry powder increased net bone calcium retention compared with no treatment in healthy postmenopausal women: a randomized crossover trial.

BACKGROUND: Preclinical studies suggest that blueberry consumption is associated with improved bone health. OBJECTIVES: We conducted a blueberry dose-response study in ovariectomized (OVX)-rats that informed a study in postmenopausal women using the urinary appearance of calcium (Ca) tracers from prelabeled bone to reflect changes in bone balance. We hypothesized that blueberry consumption would reduce bone loss in a dose-dependent manner compared with no treatment. METHODS: OVX rats were fed 4 doses of blueberry powder (2.5%, 5%, 10%, and 15%) in randomized order to determine bone 45Ca retention. Fourteen healthy, nonosteoporotic women ≥4 y past menopause were dosed with 50 nCi of 41Ca, a long-lived radioisotope, and equilibrated for 5 mo to allow 41Ca deposition in bone. Following a 6-wk baseline period, participants were assigned to a random sequence of 3 6-wk interventions, a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 0.75, 1.5, or 3 cups of fresh blueberries incorporated into food and beverage products. Urinary 41Ca:Ca ratio was measured by accelerator mass spectrometry. Serum bone resorption biomarkers and urinary polyphenols were measured at the end of each control and intervention period. Data were analyzed using a linear mixed model and repeated measures analysis of variance. RESULTS: In both OVX rats and postmenopausal women, blueberry interventions benefited net bone calcium balance at lower but not at higher doses. In women, net bone calcium retention increased by 6% with the low (95% CI: 2.50, 8.60; P < 0.01) and 4% with the medium (95% CI: 0.96, 7.90; P < 0.05) dose compared with no treatment. Urinary excretion of hippuric acid increased dose-dependently with blueberry consumption. No significant relationships were found between bone resorption biomarkers, 25-hydroxyvitamin D, and interventions. CONCLUSIONS: Moderate consumption (<1 cup/d) of blueberries may be an effective strategy to attenuate bone loss in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT02630797.

Call for change in prenatal counseling for Down syndrome.

The American Journal of Medical Genetics Part A is to be congratulated for taking a leadership role by publishing a number of papers challenging the status quo of prenatal counseling for Down syndrome and of care for children and adults with Down syndrome. Parents want to know about the future abilities and potential of their fetus with Down syndrome, not simply negative medical information that may be outdated. Those providing counseling and those providing medical care could benefit from contact with individuals with Down syndrome outside the medical context. It is imperative that each person with Down syndrome be viewed as a unique individual with particular talents. Medical care providers should work with parents to help the child or adult with Down syndrome reach his/her goals.

Down syndrome: coercion and eugenics.

Experts agree that coercion by insurance companies or governmental authorities to limit reproductive choice constitutes a eugenic practice. We discuss discrimination against families of children with Down syndrome who chose not to have prenatal testing or chose to continue a pregnancy after a prenatal diagnosis. We argue that this discrimination represents economic and social coercion to limit reproductive choice, and we present examples of governmental rhetoric and policies condoning eugenics and commercial policies meeting criteria established by experts for eugenics. Our purpose is to sensitize the clinical genetics community to these issues as we attempt to provide the most neutral nondirective prenatal genetic counseling we can, and as we provide postnatal care and counseling to children with Down syndrome and their families. We are concerned that if eugenic policies and practices targeting individuals with Down syndrome and their families are tolerated by clinical geneticists and the broader citizenry, then we increase the probability of eugenics directed toward other individuals and communities.

Down syndrome: issues to consider in a national registry, research database and biobank.

As the quality of life for individuals with Down syndrome continues to improve due to anticipatory healthcare, early intervention, mainstreaming in schools, and increased expectations, the lack of basic information regarding individuals with Down syndrome is being recognized, and the need to facilitate research through a national registry, research database and biobank is being discussed. We believe that there should not be ownership of the samples and information, but instead prefer stewardship of the samples and information to benefit the participants who provided them. We endorse a model with data and sample managers and a research review board to interface between the investigators and participants. Information and samples would be coded, and only a few data managers would know the relationship between the codes and identifying information. Research results once published should be included in an online newsletter. If appropriate, individual results should be shared with participants. A Down syndrome registry, research database and biobank should be accountable to participants, families, medical care providers, government, and funding sources.

Personalized medicine for individuals with Down syndrome.

As the cost of whole genome analysis decreases, we have the opportunity to explore the interactions of various gene changes in an individual that lead to their particular phenotype. This will provide the ability to move from the epidemiologic study of groups, in which, the individuals are treated collectively and homogenously, to personalized medicine, and a model in which the individual is recognized and treated as a distinct entity. We will be applying personalized medicine to individuals with Down syndrome in order to understand and develop biomarkers for increased risk of co-morbidities. Personalized medicine will change the "culture of intractability" of Down syndrome.

Down syndrome: national conference on patient registries, research databases, and biobanks.

A December 2010 meeting, "Down Syndrome: National Conference on Patient Registries, Research Databases, and Biobanks," was jointly sponsored by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) at the National Institutes of Health (NIH) in Bethesda, MD, and the Global Down Syndrome Foundation (GDSF)/Linda Crnic Institute for Down Syndrome based in Denver, CO. Approximately 70 attendees and organizers from various advocacy groups, federal agencies (Centers for Disease Control and Prevention, and various NIH Institutes, Centers, and Offices), members of industry, clinicians, and researchers from various academic institutions were greeted by Drs. Yvonne Maddox, Deputy Director of NICHD, and Edward McCabe, Executive Director of the Linda Crnic Institute for Down Syndrome. They charged the participants to focus on the separate issues of contact registries, research databases, and biobanks through both podium presentations and breakout session discussions. Among the breakout groups for each of the major sessions, participants were asked to generate responses to questions posed by the organizers concerning these three research resources as they related to Down syndrome and then to report back to the group at large with a summary of their discussions. This report represents a synthesis of the discussions and suggested approaches formulated by the group as a whole.

Skeletal Protection and Promotion of Microbiome Diversity by Dietary Boosting of the Endogenous Antioxidant Response.

There is an unmet need for interventions with better compliance that prevent the adverse effects of sex steroid deficiency on the musculoskeletal system. We identified a blueberry cultivar (Montgomerym [Mont]) that added to the diet protects female mice from musculoskeletal loss and body weight changes induced by ovariectomy. Mont, but not other blueberries, increased the endogenous antioxidant response by bypassing the traditional antioxidant transcription factor Nrf2 and without activating estrogen receptor canonical signaling. Remarkably, Mont did not protect the male skeleton from androgen-induced bone loss. Moreover, Mont increased the variety of bacterial communities in the gut microbiome (α-diversity) more in female than in male mice; shifted the phylogenetic relatedness of bacterial communities (ß-diversity) further in females than males; and increased the prevalence of the taxon Ruminococcus1 in females but not males. Therefore, this nonpharmacologic intervention (i) protects from estrogen but not androgen deficiency; (ii) preserves bone, skeletal muscle, and body composition; (iii) elicits antioxidant defense responses independently of classical antioxidant/estrogenic signaling; and (iv) increases gut microbiome diversity toward a healthier signature. These findings highlight the impact of nutrition on musculoskeletal and gut microbiome homeostasis and support the precision medicine principle of tailoring dietary interventions to patient individualities, like sex. © 2020 American Society for Bone and Mineral Research (ASBMR).

An inflection point of serum 25-hydroxyvitamin D for maximal suppression of parathyroid hormone is not evident from multi-site pooled data in children and adolescents.

In adults, maximal suppression of serum parathyroid hormone (PTH) has commonly been used to determine the sufficiency of serum 25-hydroxyvitamin D [25(OH)D]. In children and adolescents, the relationship between serum 25(OH)D and PTH is less clear and most studies reporting a relationship are derived from relatively small samples and homogeneous cohorts. Our objective was to determine the relationship between serum 25(OH)D and PTH in children and adolescents from a large and diverse U.S. cohort and to identify a point of inflection of serum 25(OH)D for maximal suppression of serum PTH. Data from 735 participants, ages 7-18 y, were pooled from 3 study sites located in Indiana, Texas, and Massachusetts. A two-phase linear spline was used to model the relationship between serum 25(OH)D and PTH. The value of serum 25(OH)D for maximal suppression of serum PTH was identified as the inflection point of the spline. Before adjustment for site, the inflection point of serum 25(OH)D for maximal suppression of serum PTH was 92.4 nmol/L (95% CI: 62.2, 130.7). After adjusting for site, the point of inflection was poorly defined and the relationship between serum 25(OH)D and PTH appeared to be linear. The lack of an inflection point of serum 25(OH)D for maximal suppression of PTH brings into question the value of using maximal suppression of serum PTH as a basis for determining optimal serum 25(OH)D for healthy children and adolescents.

Adiposity, Insulin Resistance, and Bone Mass in Children and Adolescents.

Context: Insulin resistance is an adverse health outcome that accompanies obesity. Fat mass is negatively associated with the bone mass after adjustment for confounders. Insulin resistance might be an intermediary in this relationship. Objective: To determine whether insulin resistance is an intermediary in the relationship between adiposity and bone mass in adolescents. Design: Cross-sectional secondary analysis of baseline data from a previous randomized trial. Setting: University research facility. Participants: A total of 240 adolescents (68% female), aged 7 to 15 years. Main Outcome Measures: Using dual energy x-ray absorptiometry, bone mineral content (BMC), areal bone mineral density, lean mass, and fat mass were measured. Skeletal sites of interest included the total body and lumbar spine (LS). Waist circumference was measured using an anthropometric tape measure. Insulin and glucose were measured in fasting sera, and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Path analysis was performed to determine whether the relationship between adiposity and bone was mediated through insulin resistance. Results: Fat mass (r = 0.467; P < 0.001) and waist circumference (r = 0.487; P < 0.001) correlated positively with HOMA-IR. Controlling for race, sex, maturation, lean mass, and height, fat mass, waist circumference, and HOMA-IR were negatively associated with LS BMC and total body areal bone mineral density (P < 0.05 for all). Additionally, path models for fat mass (95% CI, -5.893 to -0.956) and waist circumference (95% CI, -15.473 to -2.124) showed a negative relationship with LS BMC via HOMA-IR. Conclusions: These results support an intermediary role of insulin resistance in the relationship between adiposity and LS bone mass.

Vitamin D status and calcium metabolism in adolescent black and white girls on a range of controlled calcium intakes.

BACKGROUND: There are limited data in adolescents on racial differences in relationships between dietary calcium intake, absorption, and retention and serum levels of calcium-regulating hormones. OBJECTIVES: The aim of this study was to investigate these relationships cross-sectionally in American White and Black adolescent girls. METHODS: Calcium balance studies were conducted in 105 girls, aged 11-15 yr, on daily calcium intakes ranging from 760-2195 mg for 3-wk controlled feeding periods; 158 observations from 52 Black and 53 White girls were analyzed. RESULTS: Black girls had lower serum 25-hydroxyvitamin D [25(OH)D], higher serum 1,25-dihydroxyvitamin D, and higher calcium absorption and retention than White girls. Calcium intake and race, but not serum 25(OH)D, predicted net calcium absorption and retention with Black girls absorbing calcium more efficiently at low calcium intakes than White girls. The relationship between serum 25(OH)D and serum PTH was negative only in White girls. Calcium intake, race, and postmenarcheal age explained 21% of the variation in calcium retention, and serum 25(OH)D did not contribute further to the variance. CONCLUSIONS: These results suggest that serum 25(OH)D does not contribute to the racial differences in calcium absorption and retention during puberty.

Predictors of calcium retention in adolescent boys.

CONTEXT: The relationship between calcium (Ca) intake and Ca retention in adolescent boys was recently reported. OBJECTIVE: This study evaluated the influence of Ca intake, serum hormone levels, biomarkers of bone metabolism, habitual physical activity, habitual Ca intake, and physical fitness on Ca retention in the same sample. DESIGN: This study was a randomized, cross-over design that consisted of two 3-wk metabolic balance periods. SETTING: The study took place on a university campus as a summer camp. PATIENTS OR OTHER PARTICIPANTS: A total of 31 American white boys (13-15 yr) participated in the study. INTERVENTIONS: Each subject consumed a controlled diet with one of five high-low Ca intake pairs that ranged from 670-2003 mg/d, which was manipulated utilizing a fortified beverage. MAIN OUTCOME MEASURES: Ca retention was determined by Ca intake minus urinary and fecal Ca excretion during each balance period. RESULTS: Ca intake explained 21.7% of the variability in Ca retention, and serum IGF-I concentration explained an additional 11.5%. Other serum hormone levels did not significantly add to the model. Biomarkers of bone metabolism, habitual physical activity, habitual Ca intake, and physical fitness were not significant predictors of Ca retention in adolescent boys. CONCLUSIONS: IGF-I, a regulator of growth during puberty, is an important predictor of Ca retention in adolescent boys. However, dietary Ca intake is an even greater predictor of Ca retention during this period of growth.

Knowledge to action: implementing a guideline for second stage labor.

PURPOSE: To quantify practice changes associated with implementing a clinical practice guideline for the second stage of labor in term nulliparous women with epidural anesthesia and to describe the lessons learned about knowledge translation. The main clinical practice guideline recommendation was waiting up to 2 hours before pushing after full dilatation. DESIGN AND METHODS: Pre- and post-evaluation of clinical outcomes and knowledge translation strategies associated with implementing the second stage of labor clinical practice guideline at two birthing units within a large teaching hospital. RESULTS: The implementation of the clinical practice guideline resulted in a significant increase in median waiting time before pushing of 33 minutes at Site 1. This change was also reflected in the twofold increase in the proportion of women waiting longer than 120 minutes before pushing at this site. There was no change in waiting time at Site 2. The duration of the second stage did not change significantly at either site. The median pushing time decreased at both sites but was only statistically significant at Site 1. CLINICAL IMPLICATIONS: Bringing about practice change in obstetrics is complex. The measured change in this study was less than we expected. Greater success might have been achieved by enhancing feedback to care providers and more frequent audits of practice. We need to better understand the subtle influences in attitude and culture that prevented successful implementation in one site. For units considering a similar process, we recommend a commensurately greater level of presence in the units to encourage compliance with the clinical practice guideline in order to achieve the desired level of practice change.

Twenty-Four-Hour Urine Phosphorus as a Biomarker of Dietary Phosphorus Intake and Absorption in CKD: A Secondary Analysis from a Controlled Diet Balance Study.

BACKGROUND AND OBJECTIVES: Twenty-four-hour urine phosphorus is commonly used as a surrogate measure for phosphorus intake and absorption in research studies, but its reliability and accuracy are unproven in health or CKD. This secondary analysis sought to determine the reliability and accuracy of 24-hour urine phosphorus as a biomarker of phosphorus intake and absorption in moderate CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Eight patients with stage 3-4 CKD participated in 2-week balance studies with tightly controlled phosphorus and calcium intakes. Thirteen 24-hour urine collections per patient were analyzed for variability and reliability of 24-hour urine phosphorus and phosphorus-to-creatinine ratio. The accuracy of 24-hour urine phosphorus to predict phosphorus intake was determined using a published equation. The relationships of 24-hour urine phosphorus with phosphorus intake, net absorption, and retention were determined. RESULTS: There was wide day-to-day variation in 24-hour urine phosphorus within and among subjects (coefficient of variation of 30% and 37%, respectively). Two 24-hour urine measures were needed to achieve ≥75% reliability. Estimating dietary phosphorus intake from a single 24-hour urine resulted in underestimation up to 98% in some patients and overestimation up to 79% in others. Twenty-four-hour urine phosphorus negatively correlated with whole-body retention but was not related to net absorption. CONCLUSIONS: From a sample of eight patients with moderate CKD on a tightly controlled dietary intake, 24-hour urine phosphorus was highly variable and did not relate to dietary phosphorus intake or absorption, rather it inversely related to phosphorus retention.

Behavioral Intervention in Adolescents Improves Bone Mass, Yet Lactose Maldigestion Is a Barrier.

Calcium intake during adolescence is important for attainment of peak bone mass. Lactose maldigestion is an autosomal recessive trait, leading to lower calcium intake. The Adequate Calcium Today study aimed to determine if a school-based targeted behavioral intervention over one year could improve calcium intake and bone mass in early adolescent girls. The school-randomized intervention was conducted at middle schools in six states over one school year. A total of 473 girls aged 10-13 years were recruited for outcome assessments. Bone mineral content (BMC) was determined by dual energy X-ray absorptiometry. Dietary calcium intake was assessed with a semi-quantitative food frequency questionnaire. Baseline calcium intake and BMC were not significantly different between groups. After the intervention period, there were no differences in changes in calcium intake and BMC at any site between groups. An unanticipated outcome was a greater increase in spinal BMC among lactose digesters than lactose maldigesters in the intervention schools only (12 months) (6.9 ± 0.3 g vs. 6.0 ± 0.4 g, p = 0.03) and considering the entire study period (18 months) (9.9 ± 0.4 vs. 8.7 ± 0.5 g, p < 0.01). Overall, no significant differences between the intervention and control schools were observed. However, lactose digesters who received the intervention program increased bone mass to a greater extent than lactose maldigesters.