Objectives: Hyperparathyroidism (HPT) in renal transplant recipients may present as persistence of pre-transplant HPT or a new onset post-transplant HPT. Parathyroid scintigraphy (PS) and ultrasonography are commonly utilized for the preoperative identification of abnormal parathyroid glands. The aim of this study was to evaluate the value of repeat PS in renal transplant recipients with HPT.
Methods: For this study, 28 pairs of sequential PS images (9 pairs pre-transplant/post-transplant and 19 pairs serial post-transplant evaluations) performed in a total of 19 patients were evaluated. Of the patients, 7 patients had 3, and 1 patient had 4 sets of serial images. On PS, the number, site and uptake/retention (U/R) degree of detected parathyroid glands were recorded. Thyroid gland uptake was graded as increased or decreased based on visuallly evaluated uptake comparison relative to the submandibular glands.
Results: One patient had a nonlocalizing scan on both studies. In 68% of serial scans (n=19), no change was observed in the number and site of detected parathyroid glands on the subsequent study. Detected gland number decreased in 4 and increased in 4 cases. Among 28 cases, 7 (25%) had either increase in the number of detected glands or in the U/R intensity on the subsequent study. Thyroid gland uptake was higher than submandibular activity in 11 cases on initial PS (39%) and in 16 cases on the second study (57%).
Conclusions: Our results suggest that, in renal transplant recipients with HPT, it is more likely to have similar results on a repeat PS study. A change in “U/R” or in the number of detected glands can be observed in some cases. In general, a repeat scan may not contribute much to sensitivity. This might be explained by the high incidence of increased thyroid gland uptake in this patient group which may be related to the use of immunosuppressive agents.