Hypercalcitoninaemia in medullary carcinoma of the thyroid and other malignancies: value of calcitonin as tumour marker.

Elevated plasma calcitonin was detected by radioimmunoassay in 19 of 99 unselected cancer patients (19%). The frequency of hypercalcitoninaemia in patients with tumours of lung, uterus, gastrointestinal tract, and urinary bladder was about 40%, in carcinoma of the breast 18%, and in carcinoma of the skin 4%. In 8 patients with bone metastases, 4 were hypercalcitoninaemic. None of 19 patients with non-malignant disorders had elevated plasma calcitonin. The highest plasma calcitonin level in cancer patients was 8200 ng/l. Urinary cyclic AMP was elevated in patients with hypercalcitoninaemia as compared with patients with normal plasma calcitonin. All 6 patients with medullary carcinoma of the thyroid had very high plasma calcitonin levels: more than 50000 ng/l in five and 30000 ng/l in one patient. Of the family members of these patients, raised plasma calcitonin was detected after stimulation with oral alcohol in 6 of 12. It is concluded that plasma calcitonin levels in excess of 10000 ng/l suggest the presence of medullary carcinoma of the thyroid, while levels below 10000 ng/l have a poor diagnostic value but should alert the clinician to look for a possible malignancy.