Inadequate vitamin D status in adolescents with substantial bone mineral density loss during the use of depot medroxyprogesterone acetate injectable contraceptive: a pilot study

STUDY OBJECTIVE

To examine vitamin D and parathormone (PTH) levels in adolescents who experienced substantial bone mineral density (BMD) loss during depot medroxyprogesterone acetate (DMPA) use.

DESIGN

A non-randomized, multi-center study, during which DMPA was administered every 12 weeks and evaluation of lumbar spine and hip BMD by dual-energy X-ray absorptiometry (DXA) was conducted every 6 months. A blood sample for vitamin D and PTH measurements was obtained from adolescents who experienced >5% BMD loss. Vitamin D deficiency was defined as 25-hydroxyvitamin D (25OHD) level of <20 ng/mL, insufficiency as 25OHD level of 20-30 ng/mL, and sufficiency as 25OHD level of >30 ng/mL.

RESULTS

Evaluation of vitamin D and PTH was carried out in 15 participants who experienced BMD loss of > or = 5% during DMPA use. At initiation of DMPA, participants had mean (+SE) age 17+1 years, gynecologic age 61+4 months, and body mass index 24+1.5 kg/m2. Racial/ethnic distribution was: Caucasian--7 girls, Hispanic--4 girls, African-American--3 girls, and other--1 girl. Six participants had BMD loss of >5% after 2 DMPA injections, five after 3 injections, one after 5 injections, one after 8 injections, one after 10 injections, and one after 13 injections. Only one girl (7%) had sufficient vitamin D. The other participants had vitamin D insufficiency (50%) or deficiency (43%). Participants' mean (+SE) PTH was 22+4 pg/mL (reference range 7-53 pg/mL), and mean (+SE) 1,25-dihydroxyvitamin D was 56+5 pg/mL (reference range 22-67 pg/mL).

CONCLUSIONS

Inadequate vitamin D status was evident among the majority of female adolescents who experienced a substantial BMD loss while using DMPA.

Recovery of bone mineral density in adolescents following the use of depot medroxyprogesterone acetate contraceptive injections

BACKGROUND

Depot medroxyprogesterone acetate (DMPA) is a highly effective progestin-only contraceptive that is widely used by adolescents. We investigated bone mineral density (BMD) changes in female adolescents during and following use of this method.

STUDY DESIGN

A multicenter, prospective, non-randomized observational study in 98 healthy female adolescents aged 12-18 years who initiated DMPA intramuscular injections for contraception and provided BMD data for up to 240 weeks while receiving DMPA and for up to 300 weeks after DMPA cessation. BMD at the lumbar spine (LS), total hip (TH) and femoral neck (FN) was assessed by dual-energy X-ray absorptiometry. A mixed model analysis of variance was used to examine BMD changes.

RESULTS

At the time of their final DMPA injection, participants had mean BMD declines from baseline of 2.7% (LS), 4.1% (TH) and 3.9% (FN) (p<.001 at all three sites). Within 60 weeks of discontinuation of DMPA, mean LS BMD had returned to baseline levels, and 240 weeks after DMPA discontinuation, the mean LS BMD was 4.7% above baseline. Mean TH and FN BMD values recovered to baseline values more slowly: 240 weeks and 180 weeks, respectively, after the last DMPA injection.

CONCLUSIONS

BMD loss in female adolescents receiving DMPA for contraception is substantially or fully reversible in most girls following discontinuation of DMPA, with faster recovery at the LS than at the hip.

Bone mineral density in postmenarchal adolescent girls in the United States: associated biopsychosocial variables and bone turnover markers

PURPOSE

During adolescence, bone formation prevails over resorption, resulting in accumulation of 40% of peak bone mass throughout this time period. Although multiple studies have explored bone mass accrual during the early stages of puberty, less is known about factors that may influence bone accrual during later years of adolescence. In the present cross-sectional study we examined relationships among bone mineral density (BMD) and demographic factors, behavioral variables, and bone metabolism markers in postmenarchal adolescent girls.

METHODS

The population was comprised of 389 healthy postmenarchal adolescent girls aged 11-18 years, who were recruited into a prospective study of the effect of depot medroxyprogesterone acetate (DMPA) on bone health in adolescents. At the baseline visit, investigators collected demographic, reproductive health, and lifestyle data, and performed a complete physical examination. Body mass index (BMI) was calculated. Before study initiation, BMD at the lumbar spine, total hip, and femoral neck was measured by dual-energy X-ray absorptiometry (DXA), and markers of bone metabolism (serum bone-specific alkaline phosphatase [BAP], serum osteocalcin, and urinary N-telopeptide [uNTX]) were measured. The baseline data from this study were analyzed to evaluate possible correlates of BMD in postmenarchal adolescent girls. Potential associations between BMD values and other parameters were assessed by analysis of variance and Pearson's correlation coefficient.

RESULTS

Participants enrolled in the study had a mean (+/- SD) chronological age of 14.9 +/-1.7 years (range 11-18), mean gynecologic age of 39.9 +/-23.0 months (range 1-120) postmenarche, and mean BMI of 23.5 +/-4.6 kg/m(2) (range 16.0-42.2). Racial/ethnic distribution was 46% African American, 35% Caucasian, and 19% other races; 9% had previously been pregnant. Positive correlations were observed between lumbar spine BMD and chronological age (r = .301, p < .0001), gynecologic age (r = .349, p < .0001), and BMI (r = .371, p < .0001). Total hip and femoral neck BMD values were significantly higher (p < .05 and p < .05, respectively) in African American participants compared with non-African American participants. Previous history of pregnancy was significantly associated with a lower BMD at the lumbar spine (p < .0001) and the total hip (p < .01) when compared with the BMD of adolescents who had never been pregnant. Cigarette smoking and alcohol use were not associated with significant differences in BMD. Negative correlations were observed between gynecologic age and the levels of BAP (r = -.564, p < .0001), osteocalcin (r = -.349, p < .0001), and uNTX (r = -.281, p < .0001), and between lumbar spine BMD and BAP (r = -.363, p < .0001), osteocalcin (r = -.129, p < .05), and uNTX (r = -.202, p < .001) levels.

CONCLUSIONS

Our data demonstrate that chronological age, gynecologic age, race/ethnicity, BMI, and previous history of pregnancy are markedly associated with BMD in postmenarchal adolescent girls. Bone accretion in the postmenarchal years continues in the face of a slowdown in bone turnover during this time period.

Self-reported physical activity and bone mineral density in urban adolescent girls

BACKGROUND

This observational study aimed to examine the prevalence of activities of daily living, as well as the impact of leisure time activities, on bone mineral density in urban adolescent girls.

METHODS

Patients completed a 23-item physical activity questionnaire at baseline, recording time spent in various activities in the previous 7 days. In addition to leisure time activities, activities of daily life were also considered. Activities were characterized and scored by metabolic intensity (METPA) and mechanical strain on bone (MECHPA). The METPA score for each activity is the product of the metabolic intensity of the activity and the time spent in the activity. The MECHPA score estimates the mechanical strain on bone from ground reaction forces. The logged scores were divided into quartiles with the lowest quartile as the reference group.

RESULTS

Four hundred fifty-five females (ages 12-18 years) completed the survey (62% black and 38% non-black). The log of the overall METPA score was a significant predictor of bone mineral density (i.e. higher METPA score predicted a higher bone mineral density, P = 0.03). A MECHPA score in the highest quartile was associated with a higher bone mineral density (P < 0.05) when compared to the other MECHPA quartiles.

CONCLUSIONS

In this population of urban adolescent girls, activities of daily living were reported with a higher frequency than sports activities. Results indicated a positive association between the time spent in metabolically intense activities and bone mineral density. There also appears to be a threshold effect for the relationship between activities with the highest mechanical strain and bone mineral density.

A Role for the 2′ Residue in the Second Transmembrane Helix of the GABAA Receptor γ2S Subunit in Channel Conductance and Gating

GABA(A) receptors composed of alpha, beta and gamma subunits display a significantly higher single-channel conductance than receptors comprised of only alpha and beta subunits. The pore of GABA(A) receptors is lined by the second transmembrane region from each of its five subunits and includes conserved threonines at the 6', 10' and 13' positions. At the 2' position, however, a polar residue is present in the gamma subunit but not the alpha or beta subunits. As residues at the 2', 6' and 10' positions are exposed in the open channel and as such polar channel-lining residues may interact with permeant ions by substituting for water interactions, we compared both the single-channel conductance and the kinetic properties of wild-type alpha1beta1 and alpha1beta1gamma2S receptors with two mutant receptors, alphabetagamma(S2'A) and alphabetagamma(S2'V). We found that the single-channel conductance of both mutant alphabetagamma receptors was significantly decreased with respect to wild-type alphabetagamma, with the presence of the larger valine side chain having the greatest effect. However, the conductance of the mutant alphabetagamma receptors remained larger than wild-type alphabeta channels. This reduction in the conductance of mutant alphabetagamma receptors was observed at depolarized potentials only (E(Cl) = -1.8 mV), which revealed an asymmetry in the ion conduction pathway mediated by the gamma2' residue. The substitutions at the gamma2' serine residue also altered the gating properties of the channel in addition to the effects on the conductance with the open probability of the mutant channels being decreased while the mean open time increased. The data presented in this study show that residues at the 2' position in M2 of the gamma subunit affects both single-channel conductance and receptor kinetics.

Low levels of 25-hydroxy vitamin D are associated with elevated parathyroid hormone in healthy adolescent females

This study aimed to investigate the relationship between 25-hydroxyvitamin D [25(OH)D)] and parathyroid hormone (PTH) levels in adolescent females residing in a northern climate. Concern regarding vitamin D status in this population is due to limited sunlight exposure in northern latitudes, decreased outdoor recreational activities, as well as decreased conversion in black girls from increased skin pigmentation. In this cross-sectional analysis, serum samples were assayed for 25(OH)D using competitive protein binding (CPB) assay and PTH with immuno-radiometric (RIA) procedures. Four hundred postmenarcheal females (12-18 years) residing in northeastern Ohio were recruited. Subjects were excluded if they had a history of bone, kidney, or liver disease, or used medications that affect bone. The primary goal was to determine serum 25(OH)D concentrations in relation to circulating PTH levels in a population of adolescent girls. The Spearman correlation test was used to compare PTH and 25(OH)D. Fit multiple split models were run to determine change in slope of the regression line when 25(OH)D and PTH were plotted. Analysis of variance was determined using modeled means with differences by race and season in the final model. Unadjusted mean serum 25(OH)D and PTH levels were 55.0+/-30.4 nmol/l and 39.4+/-20.6 ng/l, respectively. Blacks had lower 25(OH)D and higher PTH compared with non-blacks (P<0.0001), especially during the winter months. Decreasing 25(OH)D was inversely correlated with PTH (r=-0.314) (P<0.0001), and at concentrations of 25(OH)D < or =90 nmol/l, an increase in PTH was observed. Adolescents are at risk for decreased serum 25(OH)D concentrations, especially black girls. We found that the widely used cutoff for vitamin D deficiency is associated with increasing PTH levels and is below the inflection point for a change in the slope of the regression line. Our results support the need for further research to establish optimal vitamin D status in adolescent girls.

Selections from current literature: Recent developments in human HIV-1 vaccine

This article reviews recent changes in the design of HIV-I vaccine. The safety information for current vaccines has been established, and future ethical considerations are reviewed. Of recent significance, gp120 envelope vaccines are being combined with canarypox vectors in an effort to elicit a broad immune response. This will probably be the aim of future research for an ever-growing problem. A total of 10 143 AIDS cases have occurred in the USA in the year 2000.(1) The international burden is grimmer. For example, approximately 13% of South Africans between 20 and 64 years old are HIV positive. Predictions estimate this number to rise to almost 30% by 2010.(2) With many different HIV serotypes, a worldwide effective HIV vaccine is not in the near future.(3) However, the scientific community has bolstered its effort by strengthening resources and developing national and international collaboration groups focused in developing a safe and effective HIV vaccine.

Abortion in adolescence: a four-country comparison

The purpose of this study was to conduct a comparison, using qualitative analytic methodology, of perceptions concerning abortion among health care providers and administrators, along with politicians and anti-abortion activists (total n = 75) in Great Britain, Sweden, The Netherlands, and the United States. In none of these countries was there consensus about abortion prior to legalization, and, in all countries, public discussion continues to be present. In general, after legalization of abortion has no longer made it a volatile issue European countries have refocused their energy into providing family planning services, education, and more straightforward access to abortion compared with similar activities in the United States.

Adolescents: at increased risk for osteoporosis?

Perhaps the most important factor in the primary prevention of osteoporosis is the attainment of an optimal peak bone during adolescence. In addition to endogenous factors, such as genetic and ethnic background, environmental factors such as dietary habits, physical activity, and sex hormone therapy, influence the accretion of bone mass during this critical period of skeletal growth. First, calcium dietary intake in adolescents is generally well less than the current recommended RDA of 1200 mg/day. Multiple studies of children and adolescents have demonstrated increases in bone mass with dietary calcium supplementation. Second, regarding physical activity, the overall impression is that a moderate amount of particularly weight-bearing exercise has a positive impact on bone. There appears, however, to be a threshold of intensity of physical activity over which a negative impact on bone occurs, particularly when the exercise is of an anaerobic nature or occurring in very thin, amenorrheic participants. Third, previous research suggests that the various forms of hormonal contraception exert differing effects on bone mass in adolescents, with levonorgestrel implants and combined oral contraceptives may be associated with a more positive effect on bone mass compared with that observed with depot medroxyprogesterone acetate. From a clinical perspective, approaches to optimizing peak bone mass in adolescents would include increasing calcium intake, whether in the form of dairy products, fortified foods, or supplements as well as encouraging participation at a moderate level, in weight-bearing exercise. Last, in adolescents with extensive risk factors and predicted long duration of use, subdermal implants or combined oral contraceptives may be the optimal hormonal methods of birth control.

Selections from current literature. Recent advances in conjugated pneumococcal vaccination

This article reviews the current literature and recent updates with regard to childhood vaccination for Streptococcus pneumonia including: studies in immunology with antibody titres, dosages of conjugated vaccines, carriage rates of Streptococcus, side effects, comparison in certain disease states and comparison between vaccines.

Update on adolescent contraception

Recent advances in OCPs include less androgenic progestins and lower doses of ethinyl estradiol. All low-dose OCPs are safe in terms of venous thrombosis risk in appropriately chosen patients. DMPA is a safe and effective long-acting contraceptive agent; clinical attention should be directed to its most common side effect, irregular bleeding. DMPA does not seem to affect mood, and it is uncertain what impact it has on weight changes. More research needs to be conducted on its impact on adolescent bone metabolism. Norplant continues to be the only subdermal contraceptive implant marketed in the United States. It provides safe and effective contraception and has the best continuation rate of all types of hormonal contraception. Its most common side effect is irregular bleeding. Norplant may be especially well suited for adolescents who have recently been pregnant or who are not tolerating other types of contraception. Emergency postcoital contraception continues to be underused in the United States, with a lack of awareness among patients and clinicians. Mechanisms of action include a delay in ovulation and interference with implantation. Research and public health groups are striving to increase patient and provider awareness and use of emergency contraception.

The use of long-acting contraceptives in adolescents

DMPA and implants have played an important role in the attempt to prevent teenage pregnancies. Adolescent health care providers should provide continued counseling to girls using DMPA or implants and should promptly address any concern associated with these methods. Future studies are warranted to explore ways to prevent or reduce the side effects of DMPA and implants, as well as to develop new, optimal, long-acting contraceptives. Detailed baseline information should be obtained in every future study that explores the presence of side effects during the use of long-acting contraceptives.

Two threonine residues in the M2 segment of the alpha 1 beta 1 GABAA receptor are critical for ion channel function

The role of three threonine residues in the M2 hydrophobic region of the GABAA receptor has been investigated by replacing these polar residues with alanine at the 6', 10' and 13' positions of M2 in the GABAA alpha 1, and beta 1 subunits and co-expressing the mutated subunits in the baculovirus Sf9 insect cell system. GABA did not elicit a current in cells expressing either the 6' or 13' threonine to the alanine mutants. The mutant subunits formed intact heteromeric GABAA receptors as judged by the binding of [3H] muscimol or the relative level of alpha 1 protein present in the plasma membrane. In contrast, a chloride current was generated by GABA in cells expressing the 10' mutant receptor. However, the current decayed more rapidly to baseline in the continued presence of GABA in the 10' mutant receptor than in the wild type receptor. The results are discussed in terms of the possible roles of the threonine residues in the ion conduction pathway.

Different 1,4-dihydropyridines exhibit discriminating effects on passive calcium uptake in rat liver plasma membrane vesicles

The effects of a number of calcium channel effectors on Ca2+ uptake by rat liver plasma membrane vesicles was examined. Nifedipine, verapamil and diltiazem had to be present at 1 mM in order to produce > 50% inhibition of Ca2+ uptake. The two structurally similar 1,4-dihydropyridines, nicardipine and nisoldipine exhibited opposite effects; nicardipine inhibited while nisoldipine stimulated Ca2+ uptake. The results show that low concentrations (microM) of calcium channel blockers of excitable cells have little effect on Ca2+ uptake by liver plasma membrane vesicles consistent with earlier findings of others that voltage-gated calcium channels are absent in hepatocytes. However, the opposite effects of higher concentrations (ca. 1 mM) of nicardipine and nisoldipine on Ca2+ uptake suggest a discriminatory action that might be useful in studying further the mechanism of passive Ca2+ uptake by these membrane vesicles.

Acute effect of consumption/omission of breakfast on exercise tolerance in adolescents

The purpose of this study was to determine the acute effects of the consumption or omission of breakfast on exercise tolerance in adolescents. Physically active adolescents (14 males and 21 females) were randomly assigned to receive a breakfast (B) or placebo (P) after an overnight fast. Exercise tolerance tests were done 1.5 hours (test 1) and again 4 hours (test 2) after consuming B or P and consisted of cycling on a stationary bike for 4 minutes at each of four consecutive power settings: 25, 50, 75, and 100 watts. Blood glucose and beta-hydroxybutyrate concentrations were measured before both tests. VO2 and VCO2 were measured during minute 3 of cycling at loads 50 and 75 watts and were used to compute the respiratory exchange ratio (RER). Heart rates (HR) were monitored throughout the test and ratings of perceived exertion (RPE) were made at the end of each 4 min interval. Repeated measures ANOVA revealed that there were no differences in RPE; however, differences for HR and RER did exist. Mean RER values were higher for the males receiving B vs males receiving P during test 1. For females, HR were higher for P compared B, and beta-hydroxybutyrate was significantly elevated for P before test 2. The data suggest that exercise tolerance as indicated by the ratings of perceived exertion are unaffected by prior ingestion of a breakfast but breakfast does affect the physiologic responses to exercise.

Riboflavin status in urban adolescents

We compared riboflavin status in 284 healthy adolescents attending an urban university hospital clinic with that of 43 adolescents with a variety of chronic medical conditions. Riboflavin status was determined by erythrocyte glutathione reductase activity and 24-hour dietary recall of riboflavin intake. The mean activity coefficient for the healthy adolescents was 1.08 (SD +/- 0.09) and 1.10 (SD +/- 1.01) in the chronically ill group. Significantly higher values were found in females of both groups (z = 4.90, p less than 0.0001). Seventeen (7%) of the healthy teenagers and seven (16%) of the chronically ill group had biochemical evidence of riboflavin deficiency (p less than 0.02). Although the mean daily intake of riboflavin for the total group exceeded the recommended daily allowance, there was significantly lower riboflavin intake in the subgroup of adolescents who had abnormal activity coefficients (z = 3.29, p less than 0.001). These data suggest that subclinical riboflavin deficiency may occur in adolescents and that deficiency may be related to dietary intake of riboflavin.

An inventory to measure medical staff knowledge of behavioral methods with pediatric pain patients

An inventory is described for assessing medical staffs' knowledge of behavioral methods with pediatric pain patients. It was adapted from a measure designed by Sanders and Webster (1982) for use with nurses treating adult chronic pain patients. The modified inventory was administered to three groups of medical staff: (a) pediatric residents, (b) pediatric nurses and (c) medical students. A series of analyses provided data supporting the psychometric integrity of the inventory. The measure successfully discriminated trained from untrained staff. The utility of the instrument for staff assessment and development is discussed.

Increasing appointment compliance through telephone reminders: does it ring true?

This study evaluated the effectiveness of telephone reminders on appointment-keeping in young people treated for gonorrhea. Compliance with scheduled follow-up was recorded for a total of 339 patients during three two-week periods, namely, initial baseline phase, intervention phase during which attempts were made to remind the patients by telephone, and repeat baseline phase. There was no overall improvement in compliance with follow-up during intervention (31%), compared to baseline (32%). However, data from the intervention phase revealed a significantly higher rate of appointment-keeping for those patients who were contacted (44%) than for patients who were not reachable (20%). Furthermore, when we reanalyzed the data as a function of telephone ownership for all patients who did not receive a reminder, return rates were significantly higher for patients owning telephones (32%) than for those denying phone ownership (18%). Thus, we conclude that the likelihood for appointment compliance was related more to sociobehavioral factors reflected in telephone ownership than to the telephone reminders.