Urine Calcitonin in Normal Children

Abstract

SummaryAlthough it is known that calcitonin decreases bone resorption, lowers serum calcium and phosphate, and influences the urinary excretion of these ions, its effect upon skeletal maturation in growing children has not been elucidated. Conceivably, the higher serum calcitonin levels that have been reported in children may promote bone formation and growth.To study immunoreactive urine calcitonin (iCT) in normal children, we used the radioimmunoassay (RIA) which we had developed previously to measure the hormone in normal adults and to screen persons at risk for medullary thyroid carcinoma (MTC). The measurement of urine iCT by RIA is particularly useful for children at risk for this thyroid malignancy because it obviates the need for venipunctures. Two antisera, one having region specificity for the midportion of CT (Ab-IIIb) and the other having carboxyl terminal recognition (Ah-IV), were utilized for the assay.For the carboxylterminal antiserum (Ab-IV), boys of ages 7 to 12 years (mean urine iCT, (ng/mg + S.D.), 0.29 f 0.18) had urine iCT levels significantly higher than girls the same age (0.13 f 0.05) and higher than both adult males (0.16 f 0.07) and adult females (0.084 + 0.034). Boys ages 13 to 15 years (0.12 f 0.03) had urine iCT concentrations which were not different from adult males. Girls of ages 7 to 12 years (0.13 + 0.05) had iCT levels significantly lower than boys of the same age (0.29 2 0.18), but significantly higher than adult females (0.084 + 0.034). Girls ages 13 to 15 (0.11 f 0.05) had urine iCT levels not significantly different from boys of the same age (0.12 f 0.03). For the midportion antiserum (Ab-IIIb), children ages 7 to 15 (0.58 + 0.384) had urine iCT concentrations greater than adults (0.26 f 0.10), but there were not significant differences in levels between boys and girls of the same age. Gel filtration studies revealed greater amounts of higher molecular weight fractions (pU-2, -14,600 daltons; pU-3, -11,000) of urine calcitonin than were found in the urine of most normal adults and all patients with MTC.

Age-Related Association of Calcitonin with Parameters of Anthropometry, Bone and Calcium Metabolism during Childhood

“…We found that CT levels decreased with advancing Tanner stages. Silva et al [44] could support our findings by detecting a decrease of CT during puberty in a study of the early 1980s.…”

Age and sex influences on urine calcitonin-like immunoreactivity in normal subjects.

“…These findings led us to investigate uCTi levels in males and females of different ages. Silva et al (1980) reported previously that levels of uCTi fall progressively with age in children, observations which are compatible to those reported in this report. Females aged 11-15 years, whose pubertal growth spurt was completed earlier than males, had significantly lower uCTi levels than males of the same age; similar observations were found in females 7-12 years of age in the study of Silva et al (1980).…”

“…Silva et al (1980) reported previously that levels of uCTi fall progressively with age in children, observations which are compatible to those reported in this report. Females aged 11-15 years, whose pubertal growth spurt was completed earlier than males, had significantly lower uCTi levels than males of the same age; similar observations were found in females 7-12 years of age in the study of Silva et al (1980). Although there is general agreement that circulating CT levels are high in children when compard to adults, controversy exists between previous reports and our observation with regard to the uCTi in elderly subjects.…”