CHARACTERISTICS OF PRIMARY HYPERPARATHYROIDISM IN A TERTIARY REFERRAL CENTRE AND INCIDENCE OF HUNGRY BONE SYNDROME

Abstract

INTRODUCTION
Primary hyperparathyroidism (PHPT) is a common endocrine disorder discovered by routine biochemical screening. The most commonly reported aetiologies are parathyroid adenoma (80 to 85%), parathyroid hyperplasia (15%) and parathyroid cancer (5%). This condition is associated with excess morbidity and mortality.

METHODOLOGY
We described the clinical characteristics, biochemical findings and treatments that influence the outcome of parathyroidectomy and the incidence of hungry bone syndrome in our PHPT patients. We conducted a retrospective review of confirmed PHPT cases who underwent parathyroidectomy in Hospital Putrajaya, an endocrine referral centre, from January 2002 to February 2018. Electronic medical records were reviewed and patient details such as clinical data, laboratory results, medications, imaging, surgical treatment and postoperative outcomes were analysed using SPSS 17.

RESULTS
Of the 345 patients included for analysis, majority were female (n=228, 66.1%) with a mean age of 52.15 years (±14.78), with 141 subjects (41%) younger than 50 years. Majority were Malays (41.4%), followed by Chinese (38.8%) and Indian (17.7%). Hypercalcemic manifestations were seen in 82.8%, presenting as renal calculi (46.4%), bone pain (30.1%), fatigue (17.1%), gastritis (14.2%) and fracture (5.5%). While mean serum calcium at presentation was 3.10 mmol/L (±0.61), 82.6% had serum calcium more than 2.85 mmol/L and 17.2% had severe hypercalcemia (≥3.5 mmol/L). Mean levels of serum phosphate, intact parathyroid hormone and alkaline phosphatase were 0.79 mmol/L (±0.25), 27.95 pmol/L (range 5.5 to 616) and 126 IU/L (range 28 to 2879), respectively. The mean estimated glomerular filtration rate (eGFR) was 38.3 mL/min/1.73 m2, with renal impairment (eGFR <60 mL/min/1.73 m2) in 38.6%. Nearly two-thirds received at least one medical therapy preoperatively (saline diuresis, bisphosphonate or subcutaneous calcitonin). Majority of the cases were histologically confirmed adenoma (76.7%), with the rest being hyperplasia, normal or carcinoma. Hungry bone syndrome postoperatively was seen in 10.8%.

CONCLUSION
PHPT cases in our setting were more symptomatic, with higher serum calcium levels and more frequent findings of nephrolithiasis and renal impairment.