Correlation between serum calcium levels and dual‐phase 99m Tc‐sestamibi parathyroid scintigraphy in primary hyperparathyroidism

• Published in: Clinical physiology and functional imaging Vol. 32; no. 1; pp. 19 - 24
• Main Authors: Mshelia, D. S., Hatutale, A. N., Mokgoro, N. P., Nchabaleng, M. E., Buscombe, J. R., Sathekge, M. M.
• Format: Journal Article
• Language: English
• Published: 01.01.2012
• ISSN: 1475-0961; 1475-097X
• DOI: 10.1111/j.1475-097X.2011.01048.x

Summary Aim:  The goal of the study is to correlate serum calcium levels with the results of dual‐phase 99m Tc‐sestamibi parathyroid scintigraphy to find the best cut‐off level of the serum calcium that correlates with a positive presurgery. Methods:  In 111 patients, serum calcium and plasma parathormone (PTH) levels were compared with the results of the 99m Tc‐MIBI scintigraphy and with this data determined the level of calcium above which the 99m Tc‐MIBI scintigraphy was likely to be positive and below which the study was likely to be negative. Results:  In total, 11 men (18%) and 50 women (82%) had a positive 99m Tc‐MIBI study. Overall 67% of those patients with a positive 99m Tc‐MIBI study had a PTH >200 ng l −1 compared to only 9% of those with a negative 99m Tc‐MIBI scintigraphy; however, for those with a positive study on an early 99m Tc‐MIBI scintigraphy, this rose to 85%. Overall a serum calcium of >2·70 mmol l −1 was found in 82% of patients with a positive 99m Tc‐MIBI study but only 14% of those with a negative 99m Tc‐MIBI study, this is rose to 97% of patients with a parathyroid adenoma identified on early images. It is also shown that patients whose serum total calcium <2·51 mmol l −1 rarely have positive 99m Tc‐MIBI scintigraphy. Conclusion:  99m Tc‐MIBI parathyroid scintigraphy is most likely to yield identification and localization of a parathyroid adenoma when both PTH and calcium are elevated; however, although there is no lower limit of PTH which can predict a negative study, we cannot recommend 99m Tc‐MIBI parathyroid scintigraphy if the serum calcium is <2·51 mmol l −1 .