# The Impact of Thyroid Surgery on Calcium and Magnesium Homeostasis: A Prospective Study

## TL;DR

This study shows that total thyroidectomy often causes low calcium and magnesium levels, and suggests that magnesium and surgical technique may influence these outcomes.

## Contribution

The study explores the role of magnesium in post-thyroidectomy hypocalcemia and the impact of surgical dissection techniques.

## Key findings

- 15% of patients developed hypocalcemia and 11% developed hypomagnesemia after total thyroidectomy.
- Intra-capsular dissection was associated with higher postoperative ionic calcium levels compared to extra-capsular dissection.
- Postoperative parathyroid hormone levels showed similar variability to preoperative levels.

## Abstract

Objective: Total thyroidectomy constitutes one of the bread-and-butter procedures of surgeons all over the world. Like with any surgical procedure, complications form a part and parcel of the postoperative course in the hospital. Hypocalcemia represents one such prevalent complication post-total thyroidectomy. This study aimed to evaluate the impact of total thyroidectomy on calcium and magnesium levels and to assess the role of magnesium in postoperative hypocalcemia.

Methods and materials: This study was carried out at a tertiary health center over a two-year period from 2022 to 2024. It involved 100 participants with thyroid conditions (benign/malignant) who required total thyroidectomy. Patients with pre-existing conditions affecting calcium levels (e.g., chronic renal failure, medullary carcinoma thyroid, etc.) were expressly excluded. Preoperative calcium, magnesium, and parathyroid hormone (PTH) levels were recorded. Intraoperative parameters such as time and fluid volume were also measured. Postoperatively, serum calcium and magnesium levels, PTH levels, and complications like hypocalcemia and hypomagnesemia were monitored. The descriptive statistics were computed to delineate the study sample. After completion of data collection, data analysis was achieved using IBM SPSS Statistics for Windows, V. 16.0 (SPSS Inc., Chicago, IL). The chi-squared test of significance was utilized to establish statistical correlations between calcium and magnesium levels post-total thyroidectomy. A p-value of less than 0.05 was considered statistically significant.

Results: The study analyzed 100 total thyroidectomy patients. The mean age of patients in our study was 50.7±8.86 years, with 97 females and three males. The most common pathology indicating total thyroidectomy was diffuse colloid goiter (46%), followed by multinodular goiter (38%). Only a single patient had preoperative biochemical hypocalcemia or hypomagnesemia, but none exhibited symptoms. After total thyroidectomy, 15% (n=15) developed hypocalcemia, and 11% (n=11) developed hypomagnesemia. Postoperative mean PTH levels slightly decreased to 28.8±11.75 pg/dl, indicating similar variability to preoperative levels. Patients who underwent intra-capsular dissection had a mean postoperative ionic calcium level of 4.89±0.54 mg/dl, while those who underwent extra-capsular dissection had a slightly lower mean ionic calcium level of 4.72±0.76 mg/dl.

Conclusion: Hypocalcemia is one of the most prevalent complications associated with total thyroidectomy. The role of magnesium in maintaining calcium homeostasis after thyroidectomy should be further explored to improve the management of hypocalcemia. Additionally, the type of capsular dissection performed during the surgery can impact the occurrence of hypocalcemia, and using intra-capsular dissection whenever possible may help reduce the incidence of hypocalcemia.