title: Familial comparison of bone mineral density at the proximal femur and lumbar spine.
abstract: Familial resemblance of bone mineral density (BMD) was studied in the lumbar spine and three regions of the proximal femur in 41 biological mother-daughter (M-D), 42 mother-son (M-S), 24 mother-grandmother (M-G) pairs and 18 mother-grandmother-daughter (M-G-D) triads. Children were placed into three maturity categories based on an assessment of secondary sex characteristics and growth velocities. Two sets of standardized BMD Z-scores were derived for the children based on either their chronological age or their maturational status. These scores were compared with maternal Z-scores derived from age-specific norms. Similar comparisons were made between the Z-scores of the mothers and grandmothers. For all three regions of the proximal femur and for the total AP lumbar spine the correlations between Z-score values were similar and significant (P < 0.05) between the M-G and M-D pairs ranging from 0.41 to 0.57. In general, the familial correlations improved when maturity-status based Z-scores were used for comparison. The absolute BMD values measured in the grandmothers and the three maturity groups of the children--expressed as a percentage of the BMD of the mothers--showed that at the neck and the trochanteric regions of the proximal femur the late-pubescent girls and boys had a significantly (P < 0.05) greater bone density than their mothers (115-123%), whereas at the AP spine these groups averaged only 88% of their mothers BMD. This site differential was not apparent when comparing the post-menopausal grandmothers with the pre-menopausal mothers (80% at both sites). Three generation comparisons demonstrated a strong familial resemblance in bone mineral density. The value of incorporating maturity-based versus chronological-based parameters for comparison with adult measures in studies that involve growing children at different stages of development was also demonstrated.
authors.affiliation: College of Physical Education, University of Saskatchewan, Saskatoon, Canada.
authors.forename: H A
authors.initials: HA
authors.lastname: McKay
authors.forename: D A
authors.initials: DA
authors.lastname: Bailey
authors.forename: A A
authors.initials: AA
authors.lastname: Wilkinson
authors.forename: C S
authors.initials: CS
authors.lastname: Houston
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015519:Bone Density / Q000235:genetics*; D002648:Child; D005260:Female; D005269:Femur; D006801:Humans; D008297:Male; D008875:Middle Aged; D017698:Postmenopause; D017697:Premenopause; D011627:Puberty; D013131:Spine