Parathyroid Hormone as a Marker for Predicting the Severity of Hypocalcaemia Following Parathyroidectomy

The purpose of this study is to determine preoperative predictors of the severity of the hypocalcaemia following parathyroidectomy. The case records of 70 patients who underwent parathyroidectomy for primary hyperparathyroidism from 2000 to 2013 was retrospectively studied. Their symptoms at presentation, biochemical parameters serum calcium, parathyroid hormone, alkaline phosphatase and parathyroid size on ultrasound were compared with their serial post-operative serum calcium levels at 24, 48, 72 and 96 h. For the purpose of analysis, patients were divided into three groups. Group 1-asymptomatic, biochemically normal (serum calcium always ≥8.5 mgs%); Group 2-asymptomatic, biochemically below normal (at least one reading <8.5, but none <8.0); Group 3-symptomatic (any one reading <8.0). No correlation was found between the severity of the presenting symptoms, pre-operative serum calcium levels or the parathyroid size with the post-operative calcium levels in the three groups. Though preoperative serum alkaline phosphatase levels were higher in Group 3, it was not statistically significant (p = 0.069). However, preoperative serum parathyroid hormone levels significantly correlated with postoperative serum calcium levels in all three groups (p = 0.006). Pre-operative serum parathyroid hormone levels may serve as a marker for severe post-operative hypocalcaemia and thus identify patients requiring closer monitoring and longer hospitalization following parathyroidectomy.