Hypocalcemia and hypoparathyroidism after total thyroidectomy: a clinical biological study and surgical considerations.

BACKGROUND: Post-operative hypocalcemia is a common and most often transient event afterextensive thyroid surgery. It may be due to iatrogenic injury to the parathyroid glands.

AIMS: We carried out a study aimed to evaluate the incidence of hypocalcemia and hypoparathyroidism following extracapsular total thyroidectomy.

METHODS: The study was carried out in 312 patients (273 females and 39 males, whose age was between 23 and 76 years, median age 48.61 +/- 14.1) who had undergone total thyroidectomy (TT) in our department from 1995 to 1998 and in 100 patients (72 females and 28 males, whose age was between 24 and 75 years, median age 51.66 +/- 13.4) who had undergone other (non-thyroid) surgery.

RESULTS: Post-operative hypocalcemia was observed in 62 patients of the control group (62%) and the decrease of the serum calcium level lasted about 3 days, and went back to normal within the 5th day. In 2 patients undergoing total thyroidectomy, hypocalcemia was considered severe (confirmed for more than 7 days, symptomatic), these had been operated for large multinodular goitre with mediastinal extension. In these patients the symptoms arose acutely about 5 h after the operation. In both cases the clinical and biological aspects went back to normal within 10 days, after a treatment with calcium and vitamin D. Transient asymptomatic hypocalcemia was observed in 234 thyroidectomized patients (75%) and thus did not need any treatment for it.

CONCLUSION: The results obtained confirm that transient hypocalcemia can be observed after any operation; and particularly responsible is the decrease of the calcium concerning the proteins. We found that post-operative hypoparathyroidism is due to injury to the parathyroid glands (parathyroid ischaemia or surgical ablation of one or more glands). Here we see the delayed serum calcium level < or = 7.5 mg/dl or the delayed serum phosphorous level > 7.4 mg/dl. The results of our study, with 2 patients presenting transient post-operative hypoparathyroidism, contribute in confirming that the extracapsular total thyroidectomy aimed to reduce any injury to the parathyroid and to the recurrent nerves, represent the better operation also for the extended benignant thyroidopathies.