Cautious clinical interpretation of preoperative Tc-99m-Sestamibi localization scan among chronic kidney disease and transplanted patients

Introduction Chronic kidney disease (CKD) patients and kidney transplant recipients are predisposed to developing hyperparathyroidism. Although CKD is typically associated with parathyroid hyperplasia, preoperative assessment may include a 99m Tc‑MIBI localization scan, performed selectively rather than routinely, which may demonstrate findings suggestive of a parathyroid adenoma. Diagnosing an adenoma potentially eliminates the need for four-gland exploration. However, the clinical meaning of pre-operative scans among renal patients remains unclear. The study objectives are: Determine adenoma and hyperplasia prevalence in the study population and the pre-operative MIBI scan localization outcomes. Identify potential predictors for either adenoma or hyperplasia. Materials and methods Retrospective cohort study, with at least 6 months post-operative follow-up, based on laboratory, imaging, medical, and operative notes in referral medical center between 2012 and 2022. Results Among 871 parathyroidectomies, 59 patients had a relevant renal background and long-term follow-up. Of these, 31 (53%) had hyperplasia. Preoperative 99m Tc-MIBI scan demonstrated positive localization for adenoma in 73% of patients. However, 22% were later diagnosed with hyperplasia (false positive), resulting in an effective localization rate of only 56.9%. The scan had 78.57% accuracy and positive and negative predictive values of 76.66% and 83.33%, respectively. Hyperplasia was significantly associated with younger age (p=0.009) and dialysis dependence (p=0.007). Hyperplasia was correlated with relative subtle hypercalcemia (p=0.015), significant higher phosphorus (p=0.001), higher alkaline phosphatase (p<0.001), and higher PTH levels (p=0.004). Discussion Over half of CKD patients had hyperplasia. The majority of patients underwent a localization parathyroid MIBI scan. About 3/4 of scanned patients had positive adenoma localization, but only 3/4 were eventually operated on and cured as adenoma. Conclusions We demonstrate a limited benefit of MIBI scans in CKD and kidney transplant patients. We recommend either omitting the scan or performing bilateral neck exploration or at least two same-side parathyroid glands exploration to improve cure rates.