APPROACH TO A PATIENT WITH CLINICALLY AND BIOCHEMICALLY ACTIVE PRIMARY HYPERPARATHYROIDISM DESPITE NEGATIVE SESTAMIBI 99MTC

Introduction: Primary hyperparathyroidism (PHPT) resulting from increased parathyroid hormone (PTH) secretion. In 80% of cases the cause is a solitary adenoma. It occurs more often in women. The gold standard in the diagnosis of PHPT is MIBI 99m Tc scintigraphy. Patient presentation. A 35-year-old women is referred to outpatient clinic due to high values of PTH, calcium and frequent recurring nephrolithiasis. From the laboratory analysis we show: PTH 317 pg/ml, Ionized calcium 1.71 (1.16 to 1.31 mmol/L); phosphates 0.73mmol/L; Vitamine D3 18.68 ng/ml. The patient is referred for neck ultrasound and bone densitometry (DEXA). A hypoechoic nodule with dimensions of 0.69x0.63x0.67 cm is visualized on ultrasound under the right lobe of the thyroid gland. In the DEXA scan, osteopenia is detected (T-score -2.2). Sestamibi scintigraphy was performed in two repetitions where no adenoma of the parathyroid gland was detected. The patient is referred for neck computed tomography (CT); a small nodule suspicious for parathyroid adenoma is visualized. Due to the clinical manifestation and the constant high values of hypercalcemia, the patient is referred for parathyroidectomy. After the operation, a few days later, the values of PTH (63.5 pg/ml) and ionized calcium (1.18 mmol/L) were normal. Conclusion. Sestamibi scintigraphy is rarely negative during clear clinical and biochemical signs. The sensitivity of Sestamibi is 80-100%, and in cases where it is negative, especially when the volume of the nodule in PHPT is small, additional analyzes such as neck CT, 18FCholine PET/CT enable the decision-making of the definitive treatment – parathyroidectomy in PHPT.