Changes of alkaline phosphatase, inorganic phosphorus and total calcium in sera of 11 to 17 year old healthy adolescents, and their relationship to growth.

A semi-longitudinal study in 111 healthy school children, 11 years old, was started in May 1976 to evaluate age-related "normal-ranges" of two so-called "routine" blood parameters during adolescence. Follow-up examinations were performed at one-year intervals until 1982. In this paper growth velocity is described and results of estimations of alkaline phosphatase, inorganic phosphorus (Pi) and total calcium (Ca) are presented and compared with values in the literature. Peak growth velocity in girls (5.94 +/- 1.92 cm/year) occurred between 11 and 12 years, in boys (7.73 +/- 2.4 cm/year) between the age of 12 and 13 years; from the age of 14 years onwards boys were significantly taller than girls. A strong relationship (p less than 0.05) between growth and alkaline phosphatase could be shown throughout the period observed. Alkaline phosphatase activity varied within a wide range and reached mean peak values at the age of 11 years in girls (470.9 +/- 114.8 U/l) and the age of 13 in boys (514.4 +/- 135.7 U/l). Afterwards, alkaline phosphatase activity decreased towards adult levels. Inorganic phosphorus constantly decreased in both boys and girls until the age of 16, while from the age of 16 to 17 years a significant increase could be observed in both sexes. Total calcium values showed a significant increase between 12 and 13 years in boys and between 13 and 14 years in girls; after the age of 14 values decreased significantly in both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)