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Serum calcium, magnesium proteins, phosphate, and immunoparathyroid hormone were measured in 338 normal children and adolescents aged between 7 and 20 years and in 123 normal adults aged between 21 and 50 years. Protein corrected serum calcium and magnesium remained stable throughout the study. Despite hyperphosphataemia protein corrected calcium exceeded the concentrations of normal adults. Serum phosphate and the Ca X P product greatly exceeded adult values and fell rather slowly towards adult levels after the pubertal growth spurt. Serum immunoparathyroid hormone tended to exceed normal adult values and was judged high for the level of serum calcium. Similarities between mineral metabolism in childhood an adolescence and in acromegaly were striking. On this basis in the light of studies demonstrating stimulatory actions of gonadal hormones on growth hormone and of growth hormone on the secretion of parathyroid hormone and 1,25-dihydroxyvitamin D3, a unifying concept is developed. This concept places growth hormone in the unique position of being the main driver and co-ordinator during childhood and adolescence of bone growth an mineralisation on the one hand, and of blood mineral homeostasis on the other. Gonadal hormones probably express some of their actions through stimulation of growth hormone secretion and others by different mechanisms. According to this concept growth hormone is maintaining th Ca X P product at a suitable high level as long as growth hormone and gonadal hormones deliver bone matrix for mineralisation at a high rate.

The bone mineral content of the distal forearm (BMC) using single-photon absorptiometry and total body bone mineral (TBBM) using dual-photon absorptiometry were determined in 19 normal boys at different pubertal stages. A highly significant correlation between BMC and TBBM was seen (r = 0.78, P less than 0.001) with a standard error of estimate (SEE) of 13%. Subgroups of early and late pubertal stages did not show any significant differences in the regression lines indicating an identical relationship between BMC and TBBM at various stages of pubertal development although great changes in bone mineral content take place. Due to high accuracy and reproducibility of both methods, which are non-invasive and harmless, measurement of BMC is suitable to estimate changes in total mineral content of the body. This may be of importance in various diseases with disturbance in growth and bone metabolism.

Height velocity, bone mineral content (BMC), serum concentrations of alkaline phosphatase (AP), testosterone, dehydroepiandrosterone (DHEA) and androstenedione (A-dione) were determined as a part of a longitudinal study of calcium metabolism in normal male puberty. The time of maximal increase (Tm) in concentrations was calculated for 20 boys from a curve-fitting analysis program. Highly significant correlations were found between Tm testosterone and Tm BMC (r = 0.73, p less than 0.001); Tm AP and Tm BMC (r = 0.68, p less than 0.001). The mean difference in time between Tm testosterone and Tm BMC was 4.7 months and between Tm AP and Tm testosterone 0.7 month. Our data indicate a very close relationship between testosterone, osteoblastic activity, and mineralization in normal male puberty, whereas the adrenal androgens do not seem to have a major influence on the mineralization at the male puberty growth spurt phase.

Bone mineral content and total serum alkaline phosphatase were measured simultaneously in 230 normal children and adolescents aged 7-20 years. The bone mineral content showed almost no variation from the age of 7 to 13 in boys a,d 7 to 11 in girls. Thereafter a sharp increase was seen in both sexes with a highly significant sex difference between the mean values. Bone mineral content showed a fairly high correlation with age, height, weight, and surface area in boys. Before the time of the growth spurt, however, these variables were poorly correlated or not correlated at all. Concentrations of total serum alkaline phosphatase increased up to the age of 14 in boys and 11 in girls. Thereafter a rapid fall was seen in both sexes, the mean levels being significantly higher in boys. The fall approximated adult levels in boys by the age of 20 and in girls by 18. A significant negative correlation between bone mineral content and serum alkaline phosphatase was seen both in boys (r=0.71, p less than 0.001) and in girls (r=0.79, p less than 0.001).

The bone mineral content (BMC) and body height were measured in 301 normal children and adolescents aged 7--20 years, and in 8 boys with constitutional delayed puberty aged 14--17 years. Serum testosterone was measured in the last group as well as in a subpopulation of the normal children and adolescents. The growth spurt, which coincided with a steep increase of serum testosterone in boys, indicated a great change in skeletal growth and mineralisation in both sexes. After the growth spurt, linear growth slowed down considerably while bone mineralisation rose steeply. When low levels of serum testosterone were maintained, as in delayed puberty, these combined changes of skeletal growth and mineralisation did not occur. It is suggested that gonadal hormones are the true initiators of the short-lived growth spurt as well as of prolonged acceleration of bone mineralisation.

Calcium homoeostasis and bone mineralization have been the subject of many studies, but few have dealt with these aspects specifically in puberty. The main observations in our own studies - together with those in other recent reports - are summarized below. According to the aims of the present survey (Chapter 1) the results are grouped as follows: BLOOD MINERAL HOMOEOSTASIS AND ALKALINE PHOSPHATASE. The serum concentrations of calcium, total or ionized, remain remarkably constant throughout puberty, which probably reflects the important functions of the calcium ion. Serum phosphate, however, remain high in childhood, increase slightly with acceleration of growth and pubertal development and the levels then decrease toward adult values. Consequently, the pattern of the product of serum calcium and phosphate, essential for mineralization, follows that of phosphate. Serum magnesium does not change during puberty. The serum concentrations of alkaline phosphatase increase with acceleration in linear growth and pubertal development which has to be taken into consideration, in evaluation of changes in serum AP. Changes in osteoblastic activity, as expressed by AP (and BGP), are closely associated with changes in testosterone secretion with almost simultaneous increases in serum levels of both variables. It is further concluded that longitudinal study designs may add to the understanding of the growth process and rate of changes, whereas cross-sectional data are relevant to establish proper reference ranges. BONE MINERAL CONTENT. The use of photon absorptiometry in determining BMC is a precise, easy, atraumatic and reproducible method. It is shown that forearm BMC has a highly significant correlation to total body bone mineral also in the pubertal period of rapid growth. It should be noted that single measurements of BMC are of little diagnostic value in the presence of wide biological variation. A spurt in mineralization corresponding to that of height in puberty has been known since the development of the BMC technique. It is evident from our data that BMC and indices of body size are only significantly related after the start of the growth spurt. Significant increases of 25% in the BMC have been found in the year prior to PHV progressing with each PH stage. The mean time of maximal increase in forearm BMC occurred some 5 months later than that of testosterone and AP, and changes in these three variables are closely interrelated. The change in the serum concentrations of the two major adrenal androgens did not appear to be related to BMC.(ABSTRACT TRUNCATED AT 400 WORDS)

With the purpose of studying calcium metabolism at the growth spurt phase in puberty, bone mineral content (BMC) of the forearm, and serum concentrations of total alkaline phosphatase, phosphate, and calcium were determined in 36 boys every three months for about 2 years. BMC increased 35% throughout the study age period of 10.6 to 14.6 years, with a maximal rate between 12.8 and 13.8 years. In relation to growth velocity BMC rose steepest during the 12 months around peak height velocity (PHV) (p less than 0.001) and showed a progressive increase from 3 months before the first pubic hair stage (PH2) to PH4 (p less than 0.001). Serum alkaline phosphatase increased by a total of 55% throughout the age period with a diminished rate of increase from 13.5 to 14 years, around the PHV, and from PH3 to PH4.

Twenty boys were followed during their puberty for about 2 years with examinations every third month. At each examination we determined serum concentrations of 25OHD3, 1,25(OH)2D3, 24,25(OH)2D3, 25.26(OH)2D3, alkaline phosphatase (AP) and testosterone together with bone mineral content (BMC) at the distal forearm. Highly significant increases in both BMC (P less than 0.001), serum AP (P less than 0.001), and peak height velocity (PHV) followed the increase in serum testosterone. The boys were grouped according to time of maximal increase in BMC, AP, and PHV. The serum levels of the vitamin D metabolites were related to these points. No significant changes in any of the serum vitamin D metabolites were found. Thus vitamin D metabolism does not seem to be significantly influenced during the period of life when both the linear growth and bone mineralization is maximal. [ABSTRACT FROM AUTHOR]