title: Primary hyperparathyroidism: role of the preoperative oral calcium loading test in the differential diagnosis between adenoma and hyperplasia.
abstract: Whereas the sensitivity of the membrane calcium receptors is decreased in parathyroid adenoma, extracellular calcium may reduce parathyroid hormone (PTH) secretion through the protein kinase C pathway in parathyroid hyperplasia. The aim of this study was to determine the role of a preoperative oral calcium loading test in the differential diagnosis between adenoma and hyperplasia. Twenty-two subjects with adenoma (group A, age +/- standard error 56 +/-2 years, female/male 15/7), 10 individuals with hyperplasia (group H, age 54 +/-3, female/male 8/2), and 32 age and gender pair-matched controls (group C) underwent the test. Calcium and PTH were measured before and 60, 120, and 180 min after oral administration of 1 g of calcium (as gluconolactate). Product P was defined as minimal PTH concentration (pg/mL) x maximal calcium concentration (mg/dL) during the test. Ratio R was defined as relative PTH decline/relative calcium increase. The PTH decline during the test in group H was comparable to that of the controls. PTH decline <30%, Product P > 1,100, and Ratio R < 4 diagnosed adenoma with specificity of 100%, 90%, and 100%, respectively. PTH decline >60% diagnosed hyperplasia with specificity of 100%. The total accuracy of the test (65%) was comparable to that of technetium-99 m sestamibi scintigraphy (66%) and better than that of ultrasonography (58%). The test may discriminate patients with sporadic diffuse hyperplasia from individuals with solitary adenoma in cases of primary hyperparathyroidism with an indication for surgery.
authors.affiliation: Endocrine Institute, Assaf Harofeh Medical Center, Zerifin, 70300, Israel. phagag@asaf.health.gov.il
authors.forename: P
authors.initials: P
authors.lastname: Hagag
authors.forename: E
authors.initials: E
authors.lastname: Kummer
authors.forename: M
authors.initials: M
authors.lastname: Weiss
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000284:Administration, Oral; D000368:Aged; D002118:Calcium / Q000378:metabolism*; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000175:diagnosis* / Q000473:pathology; D006965:Hyperplasia / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000378:metabolism; D010282:Parathyroid Neoplasms / Q000175:diagnosis*; D011493:Protein Kinase C / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D011493:Protein Kinase C; D002118:Calcium