The relationship between technetium-99m-methoxyisobutyl isonitrile parathyroid scintigraphy and hormonal and biochemical markers in suspicion of primary hyperparathyroidism.

Objective: Technetium-99m-methoxyisobutyl isonitrile (Tc-99m MIBI) has been widely used to evaluate hyperfunctioning autonomous parathyroid glands in patients with elevated intact parathyroid hormone (iPTH) and/or calcium (Ca) level. The aim of this study was to evaluate the relationship between Tc-99m MIBI parathyroid scintigraphy and hormonal and biochemical markers in suspicion of primary hyperparathyroidism (PHPT). Methods: Dual-phase Tc-99m MIBI parathyroid scintigraphy and total serum iPTH, Ca, phosphorus (P) and albumin measurements were performed in 60 patients (52 females, 8 males; mean age, 59.38±12.51 years; range, 34 to 86 years) with suspicion of PHPT. Results: The iPTH median level was 160.3 pg/mL (47.8 to 782.6). Thirty-five of the patients had surgical resection of hyperfunctioning parathyroid glands. Of the 35 patients, parathyroid gland pathology was detected in 30 patients using scintigraphic examination. Tc-99m MIBI parathyroid scintigraphy was negative in 30 patients. The iPTH, Ca and P levels were significantly different between in the Tc-99m MIBI positive group and the negative group, respectively: For iPTH, 202.1 (47.8-782.6) pg/mL versus 111.6 (80.1-373) pg/mL; p<0.001. For Ca, 11.7±1.15 mg/dL versus 10.3±1.05 mg/dL; p<0.001 and for P levels, 2.46±0.62 mg/dL versus 3.40±0.70 mg/dL; p<0.001). There was no significant difference in serum albumin levels between the MIBI positive and MIBI negative groups (4.25±0.27 g/dL versus 4.25±0.41 g/dL; p>0.05). Tc-99m MIBI parathyroid scintigraphy showed good correlation with iPTH level and histopathological diagnosis. Sensitivity and specificity was found 83.3% and 76.7%, respectively at the level of iPTH>147.7pg/mL. Conclusions: Tc-99m MIBI parathyroid scintigraphy is most likely to produce identification and localization of a parathyroid adenoma when both iPTH and Ca are elevated as well as decreased P levels.

Background: None declared.