A new randomised trial suggests selective calcium supplementation is not superior to routine supplementation after total thyroidectomy.
“Both? Both. Both. Both is good. [both nod]” – The Road To El Dorado
Total thyroidectomy is frequently associated with hypocalcaemia, resulting from an intraoperative injury or a reduced blood supply to the parathyroid gland, both of which can lead to temporary or permanent hypoparathyroidism.
There are two main approaches to reduce the risk of hypocalcaemia following thyroidectomy: giving all patients routine supplementation with calcium and calcitriol; or only offering supplementation to patients with low postoperative parathyroid hormone levels.
There are advantages and disadvantages to each approach, meaning it can be difficult for healthcare professionals to determine which course of action to follow. Researchers have recently conducted a diagnostic randomised clinical trial to determine which of the two approaches is the most effective and safe, with their findings published in JAMA Otolaryngology – Head & Neck Surgery.
“The two strategies… demonstrated similar rates of symptomatic and biochemical hypocalcaemia at two weeks,” the researchers noted.
“Moreover, adverse events typically associated with calcium supplementation were not more common with routine prophylaxis. This finding challenges the widespread belief that short-term postoperative supplementation increases the risk of hypercalcemia-related symptoms.”
Researchers recruited 258 adult patients (18 years and older) undergoing total thyroidectomy for benign or malignant disease from three Colombian hospitals. Patients who had previously undergone parathyroid surgery, had a calcium metabolism disorder, had preexisting hypocalcaemia or who required the total thyroidectomy for non-thyroid related reasons were excluded.
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Patients were randomised on a 1:1 basis to receive either routine or selective supplementation. All patients in the routine group received calcium carbonate (1200mg three times a day) and calcitriol (0.25µg twice a day) for 15 days following surgery. In contrast, patients in the selective group only received calcium supplementation if their postoperative parathyroid hormone levels were less than 15pg/ml. Based on PTH levels, only 36% of patients in the selective group required calcium supplementation.
Of the 258 patients included in the final analysis, 141 were allocated to the C+C group and 117 to the PTH group. Although the sample sizes were slightly even, the average age of patients were similar (49 versus 50 years), as was the proportion of women (84% versus 86%) and the proportion of patients undergoing total thyroidectomy (98% versus 95%, with the remaining patients undergoing completion thyroidectomy).
Hypocalcaemia symptoms, such as perioral numbness, paraesthesia, muscle cramps and Trousseau or Chvostek signs, were present in 9% of all patients in the two-week postsurgical period and occurred at a similar rate in both groups (11% for the C+C group and 8% for the PTH group).
Similar findings occurred for biochemical hypocalcaemia in the subset of patients who had full serum data available; 16% of all patients, 18% in the C+C group and 22% in the PTH group (with no statistically significant difference between the latter two groups).
Adverse events were rare, occurring in 5% of the C+C group and 8% of the PTH group. Complications associated with calcium supplementation such as postoperative dysphonia (6% in the C+C group, 8% in the PTH group) and requiring a hospital readmission for hypocalcaemia symptoms (6% versus 4%) were also infrequent.
“A central result of this study is that the PTH-guided strategy reduced the need for supplementation, achieving a 56% to 64% absolute reduction without compromising clinical outcomes,” the researchers said.
“These findings suggest that both strategies are viable options, and the decision to use one over the other may depend on local PTH assay availability, feasibility in outpatient thyroidectomy pathways and surgeon preference.
“Nevertheless, uncertainty remains regarding cost-effectiveness, particularly in settings where the proportion of patients with PTH less than 15pg/mL is lower than the 40% observed in this trial. PTH testing may be more expensive than calcium supplementation in some settings, yet reduced overtreatment, improved workflow efficiency and shorter hospital stay could shift cost balances. [Furthermore,] false-positive PTH results may also introduce unnecessary supplementation.”
A key limitation of the study was that certain variables known to affect hypocalcaemia risk, including BMI, were not collected. In addition, not all patients in the cohort had complete serum measurements, meaning that the biochemical hypocalcaemia analyses could have been impacted by selection bias.
