PTH after Thyroidectomy as a Predictor of Post-Operative Hypocalcemia

Abstract

Post-thyroidectomy hypocalcemia is a frequent complication with significant morbidity, and has been shown to increase hospital stay and readmission rates. The evaluation of serum parathyroid hormone (PTH) levels after thyroidectomy represents a reliable method to predict post-thyroidectomy hypocalcemia, but it remains infrequently used. This retrospective study investigates serum PTH values 3 h after thyroidectomy as a predictor of hypocalcemia. In this study, we enrolled 141 patients aged between 27 and 71 years eligible for total thyroidectomy who presented with multinodular goiter, suspicious nodule on cytological examination, Graves' disease, or toxic multinodular goiter. Three hours after total thyroidectomy, 53 patients (37.6%) showed a reduction in serum PTH. Of these patients 75.5% developed hypocalcemia by 24 h after surgery and 100% were hypocalcemic after 48 h (p < 0.001). There was no significant difference attributable to the different thyroid diseases, nor to the age of the patients. PTH at 3 h after total thyroidectomy accurately predicts post-operative hypocalcemia. The early detection of patients at risk of developing post-operative hypocalcemia allows for prompt supplementation of calcium and Vitamin D in order to prevent symptoms and allows for a safe and timely discharge.

Keywords: PTH levels; hypocalcemia post-thyroidectomy; thyroid surgery.

Figure 1

Serum PTH levels are tightly regulated by a negative feedback loop. PTH is secreted by the parathyroid glands as serum calcium levels drop, inducing the bones to release more ionic calcium and stimulating the kidney and intestine to reabsorb calcium. The release of PTH is reduced as serum calcium levels increase.

Figure 2

Age distribution and mean age for each category of disease. There was no significant difference between the groups (p = 0.42). MNG: multinodular goiter, TC: thyroid cancer, TG: Graves’ disease or toxic (multi)nodular goiter.