Our stimulation data are in line with recent publications (13, 14, 19) but demonstrate a smaller interindividual variation Therefore, the previous assumption that stimulated values higher than 100 ng/L (classically obtained with the pentagastrin test) are suggestive for the presence of MTC has to be carefully reevaluated, as new cutoffs for both sexes ought to be defined on the basis of the results gained with calcium testing.
Comparison of calcium and pentagastrin tests for the diagnosis and follow-up of medullary thyroid cancer.
The pentagastrin test
is not commonly used because of the risk of inducing a peptic ulcer in the diverticulum.
In clinical practice, a patient with a calcitonin concentration higher than 10 ng/L should undergo a pentagastrin test
to exclude MCT.
The pentagastrin test was also carried out on a child who presented with the clinical signs of MTC at the age of 6 months (persistent diarrhea, calcitonin concentration of 28 ng/L).
We propose that high values do not necessarily indicate a need for a pentagastrin test, especially in infants less than 1 year: the basal value should be confirmed several weeks later before performing this type of additional testing.
The pentagastrin test for CT is the most widely used provocative test for the diagnosis of MTC and for assessment of cure after surgery for MTC in patients with undetectable basal CT concentrations.
Pentagastrin test. Pentagastrin (Pentagastrin Injection BP; Cambridge Laboratories) was administered as a slow intravenous injection over 3 min at a dose of 0.5 [micro]g/kg of body weight.
In MTC patients there was no significant difference between men and women regarding CT baseline, CT peak, and CT% values after the pentagastrin test (Table 1).
In the healthy controls and MTC patients, several transitory side effects were observed during the pentagastrin test: a feeling of substernal tightness in 38 of 40 cases, nausea in 34 of 40 cases, abdominal pain in 29 of 40 cases, tachycardia in 26 of 40 cases, generalized feeling of warmth in 23 of 40 cases, tachypnea in 20 of 40 cases, flushing in 16 of 40 cases, and headache in 5 of 40 cases.
In addition, the pentagastrin test is useful for detecting hereditary MTC carriers in families where no RET mutations are identifiable (19).
As the authors point out, the ability to detect these mutations has freed clinicians from the more invasive, less reliable pentagastrin test
(which increases serum calcitonin concentrations) as a predictor for this set of late-onset diseases, mainly medullary thyroid carcinoma (MTC).