Background. Primary hyperparathyroidism (PHPT) is a rare endocrine disorder in childhood, most commonly associated with a single parathyroid adenoma. Compared to adults, pediatric cases often present with more pronounced clinical manifestations and may lead to severe skeletal complications. This report presents a symptomatic case of PHPT complicated by extensive skeletal involvement, brown tumors, and postoperative hungry bone syndrome (HBS). Case presentation. A 16-year-old female was admitted with progressive leg pain and weight loss. Laboratory evaluation revealed marked hypercalcemia, severely elevated parathyroid hormone, hypophosphatemia, and vitamin D deficiency. Imaging findings were consistent with a parathyroid adenoma; however, the initial surgical attempt failed to localize the adenoma. Subsequent advanced imaging with four-dimensional computed tomography (4D-CT) and interventional radiology-guided localization enabled successful resection. Postoperatively, the patient developed profound and prolonged hypocalcemia with concomitant hypophosphatemia and hypomagnesemia, consistent with HBS, requiring intensive intravenous and oral calcium, calcitriol, phosphate, and magnesium replacement. Radiological and histopathological evaluations demonstrated diffuse skeletal involvement with multiple brown tumors. Conclusions. This case highlights that although rare, PHPT should be considered in the differential diagnosis of children presenting with refractory bone pain and hypercalcemia. Accurate preoperative localization of parathyroid adenomas requires advanced imaging techniques and a multidisciplinary approach. Furthermore, in patients with markedly elevated parathyroid hormone and alkaline phosphatase levels, vitamin D deficiency, and long-standing skeletal involvement, the risk of developing HBS should be anticipated and management strategies tailored accordingly.