Predicting bone mineral acquisition during puberty: data from a 3-year follow-up study in Hamamatsu, Japan

Elevated bone turnover markers predict bone mineral density accrual in adolescents with 21-hydroxylase deficiency

CONTEXT

Prognostic biomarkers for monitoring bone health in adolescents with 21-hydroxylase deficiency (21OHD) are needed.

OBJECTIVES

To assess associations between concentrations of baseline bone turnover markers (BTMs) including osteocalcin (OC) and type-I collagen C-terminal telopeptide (CTX) and changes in lumbar spine bone mineral density (LSBMD) in adolescents with classic 21OHD.

DESIGNS AND PATIENTS

A retrospective-prospective study of 33 adolescents with classic 21OHD who had baseline data for LSBMD, bone age (BA), and BTM concentrations.

METHODS

BTM concentrations were converted into z-scores according to BA. We measured LSBMD at the follow-up study visit and calculated the annual percentage change in LSBMD (%∆LSBMD).

RESULTS

At baseline, participants (55% female, 79% Tanner 5) had mean (±SD) age of 14.6 ± 3.6 years, BA 16.7 ± 2.9 years, and average glucocorticoid (GC) dose 17.3 ± 5.6 mg/m2 /day of hydrocortisone equivalent. The mean follow-up duration was 14.4 ± 5.6 months. Median (Q1-Q3) %∆LSBMD was 3.6% (0-8.5)/year. %∆LSBMD was similar among genders or 21OHD subtypes. Prednisolone versus hydrocortisone replacement resulted in lower %∆LSBMD (p = .004). %∆LSBMD was increased across tertiles of CTX z-score (p = .014). %∆LSBMD correlated negatively with GC dose (p = .01) and positively with CTX and OC z-scores (p < .01). In regression analyses, only CTX z-score positively associated with %∆LSBMD (p = .003), adjusting for sex, BA, body mass index, testosterone, 25-hydroxyvitamin D, and GC type and dose.

CONCLUSIONS

Higher GC dose and the use of prednisolone were associated with decreased LSBMD accrual in adolescents with 21OHD. CTX z-score independently associated with LSBMD accrual, suggesting its potential for prognostic bone biomarker.

The evolution of the adolescent growth spurt: Urinary biomarkers of bone turnover in wild chimpanzees (Pan troglodytes)

Life history theory addresses how organisms balance development and reproduction. Mammals usually invest considerable energy into growth in infancy, and they do so incrementally less until reaching adult body size, when they shift energy to reproduction. Humans are unusual in having a long adolescence when energy is invested in both reproduction and growth, including rapid skeletal growth around puberty. Although many primates, especially in captivity, experience accelerated growth in mass around puberty, it remains unclear whether this represents skeletal growth. Without data on skeletal growth in nonhuman primates, anthropologists have often assumed the adolescent growth spurt is uniquely human, and hypotheses for its evolution have focused on other uniquely human traits. The lack of data is largely due to methodological difficulties of assessing skeletal growth in wild primates. Here, we use two urinary markers of bone turnover-osteocalcin and collagen-to study skeletal growth in a large, cross-sectional sample of wild chimpanzees (Pan troglodytes) at Ngogo, Kibale National Park, Uganda. For both bone turnover markers, we found a nonlinear effect of age, which was largely driven by males. For male chimpanzees, values for osteocalcin and collagen peaked at age 9.4 years and 10.8 years, respectively, which corresponds to early and middle adolescence. Notably, collagen values increased from 4.5 to 9 years, suggesting faster growth during early adolescence compared to late infancy. Biomarker levels plateaued at 20 years in both sexes, suggesting skeletal growth continues until then. Additional data, notably on females and infants of both sexes, are needed, as are longitudinal samples. However, our cross-sectional analysis suggests an adolescent growth spurt in the skeleton of chimpanzees, especially for males. Biologists should avoid claiming that the adolescent growth spurt is uniquely human, and hypotheses for the patterns of human growth should consider variation in our primate relatives.

Maternal pre-pregnancy underweight is associated with underweight and low bone mass in school-aged children

INTRODUCTION

A number of studies have reported that pre-pregnancy overweight status is associated with offspring obesity, yet only a few studies have examined pre-pregnancy underweight status as it associates with offspring health. The aim of the present study was to assess the effect of pre-pregnancy underweight status in a mother on health outcomes in her offspring. To this end, the primary outcome examined in the present study was underweight status in the offspring, with a secondary outcome of offspring low bone mass.

MATERIALS AND METHODS

The present retrospective cohort study, conducted from 2008 to 2011, targeted a source population of all students registered as fifth-graders at three public elementary schools in Hamamatsu and Fukuroi cities. Maternal height and weight before and after pregnancy and offspring weight and height at birth were obtained from the Maternal and Child Health Handbook. Offspring weight and height at age 10 years were measured using standard procedures. Offspring total body less head (TBLH) bone mineral content (BMC) was determined with a dual-energy X-ray absorptiometry scanner.

RESULTS

Pre-pregnancy underweight status was found to be associated with an increased risk of an underweight status in female offspring (OR = 2.88, 95% CI 1.06-7.81). Offspring TBLH BMC in the underweight mother group was significantly lower than that in the non-underweight mother group.

CONCLUSIONS

We determined that pre-pregnancy underweight status was more likely to lead to an underweight status and low TBLH BMC in school-aged offspring.

Bone mass development is sensitive to insulin resistance in adolescent boys

PURPOSE

Insulin resistance may exert a negative influence on bone mass in childhood and adolescence. The objective was to assess the association between insulin resistance and total body less head (TBLH) bone mineral content (BMC) and to investigate whether body composition, physical activity or osteocalcin levels may influence this association.

METHODS

A longitudinal study with follow-up over more than 6 years was performed and included 562 apparently healthy participants with a mean age of 9.6 years at baseline. Participants underwent DXA scanning at baseline. At the two follow-ups, participants had performed another DXA scanning, had blood samples taken for fasting insulin, glucose and osteocalcin and had physical activity measured with an accelerometer. HOMA-IR was calculated as an index of insulin resistance.

RESULTS

HOMA-IR was negatively associated with TBLH BMC in boys at follow-ups (β = -31.4, p < 0.001) after adjustment for maturity, height, bone area, and baseline level of TBLH BMC. The negative association remained almost unchanged after further adjustments for body composition and physical activity. No association between HOMA-IR and TBLH BMC was found in girls.

CONCLUSION

Insulin resistance may be detrimental for bone development through puberty in boys independent of body composition and the level of physical activity.

Update on bone density measurements and their interpretation in children and adolescents

Following the increased awareness about the central role of the pediatric age in building bone for life, clinicians face more than ever the necessity of assessing bone health in pediatric subjects at risk for early bone mass derangements or in healthy children, in order to optimize their bone mass accrual and prevent osteoporosis. Although the diagnosis of osteoporosis is not made solely upon bone mineral density measurements during growth, such determination can be very useful in the follow-up of pediatric patients with primary and secondary osteoporosis. The ideal instrument would give information on the mineral content and density of the bone, and on its architecture. It should be able to perform the measurements on the skeletal sites where fractures are more frequent, and it should be minimally invasive, accurate, precise and rapid. Unfortunately, none of the techniques currently utilized fulfills all requirements. In the present review, we focus on the pediatric use of dual-energy X-ray absorptiometry (DXA), quantitative computed tomography (QCT), peripheral QCT (pQCT), and magnetic resonance imaging (MRI), highlighting advantages and limits for their use and providing indications for bone densitometry interpretation and of vertebral fractures diagnosis in pediatric subjects.