PОSTSURGICAL HUNGRY BONE SYNDROME IN UNRECOGNIZED SEVERE PRIMARY HYPERPARATHYROIDISM: A CASE REPORT

Abstract

Parathyroidectomy for hyperparathyroidism can be complicated with development of Hungry Bone Syndrome (HBS), a constellation of profound hypocalcemia with hypomagnesemia and hypophosphatemia. The severity of this potential life-threatening condition is related to the extent of the parathyroid-mediated high-turnover bone disease. We present a case of a 59-year-old woman developing post-surgical HBS as a result of longstanding severe unrecognized primary hyperparathyroidism (PHPT) and improper perioperative management. Our patient had a six-year history of upper gastrointestinal pain, progressive weight loss, recurrent bilateral nephrolithiasis with advanced chronic kidney disease (CKD) and chronic normocytic anemia. Due to fall related subtrochanteric fracture the patient was admitted in the local surgical hospital. Computed tomography evaluation revealed multiple osteolytic lesions in the axial and appendicular skeleton. The finding of elevated parathyroid hormone (PTH) (1355 pg/ml), hypercalcemia (3.54 mmol/l) and elevated alkaline phosphatase (ALP) led to the diagnosis of PHPT with brown tumours. 99mTc-sestamibi scan confirmed presence of left parathyroid adenoma and notable tracer uptake in the affected bones. The patient was scheduled for parathyroidectomy. Comprehensive preoperative and postoperative care was not performed, and the occurrence of HBS was not considered. Early postoperative laboratory assessment showed normocalcemia and the patient was discharged. Two months later the patient presented to our clinic with laryngeal stridor, paraesthesia of the hands, muscle weakness and confusion. Laboratory assessment revealed severe hypocalcemia (0.65 mmol/l), hypomagnesemia (0.49 mmol/l), hypophosphatemia (0.94 mmol/l), elevated PTH (406 pg/ml) and profound vitamin D deficiency (7.39 ng/ml). Diagnosis of HBS was supported by the presence of parameters reflecting diminished osteoclast activity as demonstrated by the normalisation of ALP and significant osteoblast activity denoted by 5 times normal value of osteocalcin. Moreover, preoperative risk factors for HBS were also present such as brown tumours, depleted Vitamin D and most notably, missed opportunity for preoperative prevention of HBS. Our case shows that CKD associated secondary hyperparathyroidism does not protect from HBS in longstanding and neglected PHPT with extensive bone disease. Duration of HBS is determined by the time needed for skeleton remineralization, normalisation of markers of bone turnover, withdrawal of radiological features of brown tumors and significant gain in bone mass after initiation of calcium, magnesium and calcitriol supplementation. As COVID pandemic situation ensued, our patient refused radiological assessment for bone lesion remineralization, but the presence of clinical improvement, correction of anemia and normalization of bone markers turnover allowed us to conclude that resolution of HBS occurred.