SERUM CALCITONIN IN MEDULLARY THYROID CARCINOMA

Abstract

Abstract. A radioimmunoassay for the determination of human calcitonin in 200 μl aliquots of serum has been developed using rabbit antiserum against extract of an amyloid‐producing medullary carcinoma of the thyroid gland (MCT). The assay was specific for human synthetic and native calcitonin and sensitive enough to determine normal and subnormal serum levels. No cross reaction occurred with human or bovine parathyroid hormone. The levels ( x̄ ±2 S.D.) were 0.70±0.34 ng/ ml in 115 control subjects, confirming that calcitonin is a normal serum peptide. High calcitonin levels, 2‐>800 ng/ml, were found before surgery in 21 patients with verified MCT and low levels, ≤0.40 ng/ml, after thyroidectomy in 7 of 9 patients thyroidectomized for thyroid tumours other than MCT. Our results show that this calcitonin assay has clinical value in the diagnosis of MCT, both primary and metastasizing. It is therefore of value also in the postoperative control of these patients. The levels of calcitonin correlated well with the clinical estimation of the extent of the disease.