Calcium-Pentagastrin Stimulation

Calcium-Pentagastrin Stimulation

Rationale: Calcium and pentagastrin stimulate the secretion of calcitonin by the parafollicular cells of the thyroid gland.1 This secretion is increased in patients with medullary thyroid carcinoma (MTC) relative to healthy individuals. Stimulation with the combination of calcium and pentagastrin produces better sensitivity and specificity for the diagnosis of MTC than basal calcitonin measurement or use of calcium or pentagastrin alone. The reference intervals in pg/mL established at baseline and after calcium/pentagastrin stimulation have been established by the assay manufacturer (Nichols Institute Diagnostics):

 

Baseline

1 Minute

2 Minutes

5 Minutes

10 Minutes

Adult female (n=30)

<4.6

<41

<70

<39

<23

Adult male (n=30)

<11.5

<342

10−491

8−343

<112

Protocol: The patient should fast overnight prior to the stimulation procedure. The patient should remain supine during the procedure. A baseline serum sample should be collected for calcitonin measurement. Calcium (2 mg/kg) should be administered intravenously over 60 seconds followed by pentagastrin (0.5 μg/kg) over five seconds. Samples should then be collected for calcitonin at 1, 2, 5, and 10 minutes.

Orderable Test: Calcitonin (Thyrocalcitonin), Serum, Five Specimens (026807) (Baseline, 1-, 2-, 5- and 10-minute)

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