More than 50,000 thyroid operations are performed in the United States annually, and postoperative hypoparathyroidism can occur in up to 30% of cases. To protect against the development of symptomatic hypocalcemia that occurs with postoperative hypoparathyroidism, many medical centers routinely discharge patients who have undergone thyroidectomy with prescriptions for calcium supplementation. These supplements, however, can be inconvenient for patients. They may cause adverse events (eg, constipation and nausea) and may actually suppress parathyroid hormone (PTH) production.
Patients discharged on calcium replacement after thyroidectomy usually undergo follow-up blood work to test serum calcium and PTH levels, causing loss of productivity for the patient and additional paperwork for the medical staff. Selective calcium supplementation may offer an effective means for eliminating the costs and burden associated with routine supplementation.
Selective Calcium Supplementation
“With routine calcium supplement use, clinicians must determine when and how to wean patients off supplementation when appropriate,” explains Nancy D. Perrier, MD. “Calcium supplements are relatively inexpensive, but the real burden of routine calcium supplementation comes with the additional laboratory work that is needed. Medical staff must conduct continued follow-up and communicate results to patients. Ultimately, routine supplementation increases the complexity of postoperative care.” On the other hand, according to Dr. Perrier, checking blood calcium levels shortly after thyroidectomy to determine if patients require supplementation allows providers to personalize the postoperative treatment plan with the patient prior to hospital discharge.
A New Analysis for Post-Thyroidectomy
Dr. Perrier and colleagues had a study published in Archives of Surgery that tested an algorithm for approaching post-thyroidectomy calcium supplementation based on a selective approach. Patients were analyzed during the postoperative period and were divided into two groups depending on their risk of developing postoperative hypocalcemia:
Group 1: High-risk. These patients had postoperative symptoms of hypocalcemia (eg, tingling and numbness), postoperative serum calcium levels less than 7 mg/dL, or a PTH level less than 3 pg/mL on postoperative Day 1.
Group 2: Low-risk. This group comprised all other patients in the study.
Serum calcium levels were followed throughout the postoperative period. Occurrences of symptomatic hypocalcemia and the consumption of oral calcium supplementation were recorded during hospitalization and after discharge from the hospital. Groups were analyzed to identify which factors were associated with a high risk of developing postoperative hypocalcemia.
Not all patients in Group 1 developed symptoms. The average decrease in calcium during the first 24 hours following thyroidectomy was 1.1 mg/dL for Group 1 and 0.4 mg/dL for Group 2 (Figure). All symptomatic patients in Group 1 either had a serum PTH level less than 6 pg/mL or a calcium level less than 8 mg/dL on postoperative Day 1. Further analysis was done on the entire dataset by stratifying patients according to PTH level on postoperative Day 1. Patients at highest risk of developing a serum PTH level less than 6 pg/ mL included those who had a malignant thyroid tumor, underwent a central neck dissection, or had a parathyroid gland removed at operation.
“Routine supplementation increases the complexity of postoperative care.”
“Our algorithm eliminates unnecessary calcium and vitamin D supplementation and associated blood draws after thyroidectomy for more than half [58%] of patients,” Dr. Perrier says. “Those who were female, underwent a central neck dissection, had cancer, or underwent removal of at least one parathyroid gland were more likely to be in the high-risk group [Table].” The study noted that age at operation, concomitant lateral neck dissection, preoperative vitamin D level, and number of tumor-positive lymph nodes were not significantly associated with being in the high-risk group.
Next Steps in Managing Post-Thyroidectomy Patients
In order to predict and categorize post-thyroidectomy patients for calcium supplementation, Dr. Perrier and colleagues believe that a calcium level less than 8 mg/dL and a PTH level less than 6 pg/mL on the morning of postoperative Day 1 can serve as good landmarks for use. “These two objective parameters can be useful for medical providers,” says Dr. Perrier. “This suggested regimen may decrease resource utilization (eg, medication, labs), and thus decrease cost of care.”
Furthermore, it appears that the selective algorithm from Dr. Perrier and colleagues is safe. “No patients in our study developed tetany or a hypocalcemic crisis due to low calcium levels. However, it’s important that clinicians educate all thyroidectomy patients on the symptoms of hypocalcemia so that they can tell their medical team if symptoms arise. In such cases, treatment can be initiated earlier to help avoid life-threatening situations.”