Summary
The influence of sex and age on basal and calcium stimulated immunoreactive plasma
calcitonin (iCT) were studied in 36 healthy subjects. An identical calcium stimulus,
“calcium clamp”, was applied to 10 young males, 13 premenopausal females of similar
ages and 13 postmenopausal females. A significantly greater iCT response was found
in males compared with both female groups. No age correlation in basal or calcium
stimulated iCT levels was observed despite 35 years difference in mean age between
the pre- and postmenopausal groups. A positive correlation between the induced change
in whole blood ionized calcium (B-Ca++) and the iCT response, recorded after 15 min, was seen in young subjects of both
sexes. Basal iCT and B-Ca++ were similar in all three groups. No correlation between basal iCT and basal B-Ca++, or between basal iCT and age was found. The total amounts of infused calcium per
kg body weight were equal.
The results indicate that male subjects have a greater secretory capacity of the thyroid
C-cell than females. No reduction of the secretory capacity was observed with increasing
age in females, neither was any difference found between pre- and postmenopausal females
of the iCT-response.
Key-Words:
Calcitonin
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Sex- and Age-Relation
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Calcium Infusion
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Ionized Calcium
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Calcium Clamp
