This prospective observational study aims to evaluate whether changes in ionized calcium levels measured by blood gas analysis during the preoperative, intraoperative, and postoperative periods can predict postoperative hypocalcemia in patients undergoing total thyroidectomy. Ionized calcium values obtained at predefined perioperative time points will be compared with postoperative biochemical and clinical hypocalcemia outcomes.

Postoperative hypocalcemia is a common complication after total thyroidectomy and may be associated with changes in calcium homeostasis and parathyroid function. Early identification of patients at risk for postoperative hypocalcemia may help guide postoperative monitoring and calcium replacement strategies.

This prospective observational study included patients who underwent total thyroidectomy. Ionized calcium levels were measured by blood gas analysis at predefined perioperative time points, including the preoperative, intraoperative, and postoperative periods. Serum parathyroid hormone levels were also recorded. The study evaluated the relationship between perioperative changes in ionized calcium levels, postoperative parathyroid hormone changes, and the development of postoperative hypocalcemia.

The primary objective was to determine whether perioperative ionized calcium changes can predict postoperative hypocalcemia after total thyroidectomy. Secondary objectives included evaluating the association between postoperative parathyroid hormone changes and postoperative hypocalcemia and assessing the diagnostic performance of ionized calcium measurements for predicting hypocalcemia.

Inclusion Criteria:

• Patients aged 18 to 75 years
• Present to the General Surgery Clinic of Başakşehir Çam and Sakura City Hospital
• Diagnosis of thyroid disorders according to ICD code E07
• Scheduled to undergo total thyroidectomy due to toxic multinodular goiter, multinodular goiter, or papillary carcinoma
• Provide informed consent to participate in the study.

Exclusion Criteria:

• Patients with preoperative parathyroid disorders associated hypocalcemia or hypercalcemia.
• Patients with a history of previous thyroidectomy
• Patients with a history of previous parathyroidectomy
• Patients with a history of previous neck surgery.
• Patients with chronic kidney disease.
• Patients with a history of non-thyroid malignancy.

Patients admitted to Başakşehir Çam and Sakura City Hospital who are scheduled to undergo total thyroidectomy.