Background: Recent NICE guidelines1 suggest imaging the parathyroid with ultrasound as first line prior to parathyroidectomy, MIBI as an alternative and surgical exploration if discordant. Investigation should also include a renal ultrasound and DEXA. This audit compares a single surgeon practice in one hospital to the guidelines.
Methods and Results: All patients with a parathyroidectomy performed by a single surgeon between July 2016 and July 2018 inclusive were eligible. Biochemistry and imaging was accessed from local hospital IT systems and compared to histology and post-op calcium as gold standard. 45 patients were eligible; 33 patients were included (exclusions: 10 tertiary hyperparathyroidism, 1 incomplete data, 1 repeat entry). 76% (n=25) had DEXA scans. 88% (n=29) had 24 h urinary calcium, (elevated in 52% (n=15)). 33% (n=11) of patients had a renal ultrasound (3 identifying renal calculi). All patients had parathyroid imaging: 36 MIBI +/− SPECT scans; 7 parathyroid ultrasounds performed by 4 sonographers. In patients with adenoma on final diagnosis (n=27), MIBI correctly identified adenoma in 28 cases 64% (n=18). 2/4 (50%) ultrasound identified a lesion. 18.5% (n=5) showed no concordance between investigations and operative findings. Full or partial concordance was achieved in 81.5% (n=22). Postoperatively, three patients remained hypercalcaemic despite parathyroid tissue removal (two diagnosed as sarcoidosis, despite elevated PTH; one under investigation) but surgery identified all other adenomas.
Conclusion: Renal US has traditionally only been used in those with high urinary calcium, due to low pick up rate of incidental renal stone disease. Surgery remains gold standard for identification of parathyroid lesions. MIBI detection rate was low which might reflect the mild disease considered for operation. Parathyroid US detection rate remains low (and infrequently used) contributed to by multiple operators. 4D-CT remains a useful addition when diagnostic doubt.
1. Hyperparathyroidism (Primary): Diagnosis, Assessment and Initial Management. London: NICE; 2019