The Risk Factors of Hypocalcemia after Total Thyroidectomy: What is the Main Cause of Transient Hypocalcemia?

Hong, Suck Joon; Lee, Chung Seon; Kim, Yon Seon

Abstract

PURPOSE
Parathyroid injury and metabolic events are known causes of post thyroidectomy hypocalcemia and many other clinical risk factors are also noted. This retrospective study was undertaken to determine the main causative factor of transient hypocalcemia after total thyroidectomy.
METHODS
237 patients underwent total thyroidectomy and 10 patients underwent lobectomy were enrolled in this study. The incidence of transient and permanent hypocalcemia was investigated and we evaluate the risk factors. In 36 patients who underwent total thyroidectomy and 10 patients who underwent lobectomy, serum total calcium and, ionized calcium, i-PTH were measured at post operative day 1, 3, 7 and compared according to the number of preserved parathyroid glands.
RESULTS
The incidence of transient and permanent hypocalcemia after total thyroidectomy was 3.4% (8/237) and 0.4% (1/237) respectively. Among the investigated risk factors, the number of preserved parathyroid gland was the only significant factor for hypocalcemia and, tumor extent, extent of central lymph node dissection and, lateral lymph node dissection were not the significant risk factors. The incidence of hypocalcemia was closely related to the number of preserved parathyroid gland (0 (66.7%), 1 (5.2%), 2 (0.7%), 3 (0%), 4 (0%))(P<0.001). The levels of serum total calcium, ionized calcium and, i-PTH were significantly different between the patients in whom only 1 parathyroid gland was preserved and more than 1 gland preserved at post operative day 1, 3. However there was no difference between two groups at post operative day 7.
CONCLUSION
The technical aspect of parathyroid preservation is the most important factor for post thyroidectomy hypocalcemia.