Endocrine Abstracts

Background: Paediatric primary hyperparathyroidism (PHP) caused by adenoma of the parathyroid gland is rare. The investigation to localise parathyroid adenomas using imaging modalities currently available in children can be challenging, due to the small dimensions of functional parathyroid adenomas.

Case: An 8-year-old male had an incidental finding of hypercalcaemia. Adjusted calcium was raised 3.59 mmol/l (2.15 – 2.74 mmol/l) with normal phosphate 0.89 mmol/l (0.81 – 1.61 0.89 mmol/l), PTH was elevated 13.1 pmol/l (1.1 – 6.9 pmol/l). Urine calcium: creatinine ratio was 1.27 mm/mm Cr (0 – 0.6 mm/mm Cr). The patient was managed with intravenous fluids, furosemide and pamidronate. After an initial brief response, he re-presented due to persisting hypercalcaemia. Cinacalcet was introduced and doses were gradually titrated to maintain calcium within normal range. Conventional imaging modalities, neck ultrasound followed by planar scintigraphy and delayed SPECT/CT, were insufficient to localise a parathyroid adenoma. Additional neck MRI was performed for increased uptake in the left submandibular region on SPECT/CT, but was also inconclusive. Following this, a ¹⁸Fluorocholine PET/CT scan was performed, which showed a functional lesion in the left lower parathyroid gland. This facilitated a targeted surgical excision of the parathyroid adenoma, with the support of intra-operative PTH monitoring. Operative findings accurately mirrored those of the imaging. Post-operative PTH normalised within one day and subsequently all medications were discontinued.

Discussion: This case highlights the role of ¹⁸Fluorocholine PET/CT in the investigation of patients with suspected parathyroid adenoma. Recent studies have highlighted the sensitivity and specificity of ¹⁸Fluorocholine PET/CT imaging in identifying parathyroid adenomas, compared to other imaging modalities. Other advantages include low radiation and short scan time. The challenges of ¹⁸Fluorocholine PET/CT include limited availability of the tracer and that often the test is required to be performed in an adult care setting, which requires adaptation of dosing and patient care protocols. With more frequent use and therefore experience, and given such sensitivity and specificity, ¹⁸Fluorocholine PET/CT may become a preferred option for the investigation of patients with PHP in future.