Intraoperative high-dose calcium stimulation test in patients with sporadic medullary thyroid carcinoma is highly accurate in predicting lateral neck metastases.

BACKGROUND: Intraoperative measurement of calcitonin is not highly accurate in predicting the completeness of the operative resection after total thyroidectomy combined with central neck dissection (TT-CND) in patients with medullary thyroid carcinoma (MTC). We evaluated whether an intraoperative, high-dose calcium stimulation test (IO-CST) after TT-CND can predict lateral neck involvement. METHODS: Eleven patients who underwent primary operation for sporadic MTC were included. High-dose (25 mg/kg) calcium gluconate was administered after TT-CND with calcitonin measured at 2, 5, and 10 minutes after the calcium gluconate infusion. RESULTS: There were 2 males and 9 females (mean age, 51 years; range, 18-88). Three patients showed lateral neck metastases. At a mean follow-up of 7.0 months (range, 2-10), 1 patient showed distant metastases and 1 a slightly increased calcitonin level. After IO-CST, serum calcitonin increased in all the 3 patients with lateral neck metastases, and it remained unchanged or decreased in the other patients without lateral neck metastases. Percent variation of serum calcitonin after IO-CST was 92% in patients with lateral neck metastases and -3.1 ± 4.9% in patients without lateral neck metastases. CONCLUSION: Calcitonin measurement after IO-CST in patients with sporadic MTC can be highly accurate in predicting lateral neck nodes involvement. These results could represent a stimulus toward the development of a quick calcitonin assay.

Post-thyroidectomy hypocalcemia is related to parathyroid dysfunction even in patients with normal parathyroid hormone concentrations early after surgery.

BACKGROUND: Hypocalcemia may develop even in the presence of normal postoperative parathyroid hormone (PTH) concentrations. We aimed to identify risk factors of hypocalcemia in patients with normal PTH concentration early after total thyroidectomy (TT). METHODS: We included 1,504 consecutive patients who underwent TT between January 2012 and December 2013. Significant hypocalcemia was defined as serum calcium concentrations of <8.0 mg/dL. RESULTS: Overall, 333 patients had subnormal PTH 4 hours after surgery (4-hour PTH; <10 pg/mL) and received oral calcium (OC) and calcitriol supplementation. Among the 1,171 patients with normal 4-hour PTH (≥ 10 pg/mL; euparathyroid), 211 experienced hypocalcemia and required OC administration. Among the euparathyroid patients, no difference was found between normocalcemic and hypocalcemic patients in terms of age, hormonal status, preoperative PTH, 25-hydroxy vitamin D (25OH-VD), magnesium, and phosphate concentrations. On univariate analysis, euparathyroid hypocalcemic patients were more frequently females, had significantly lower preoperative serum calcium and 4-hour PTH concentrations, and greater decreases in PTH. Independent risk factors for hypocalcemia with normal 4-hour PTH were preoperative serum calcium concentration and PTH decline of ≥ 50%. CONCLUSION: Female sex, toxic goiter, and 25OH-VD deficiency are not risk factors for post-TT hypocalcemia. Relative parathyroid insufficiency seems to be the principal mechanism of post-thyroidectomy hypocalcemia, even in patients with normal postoperative PTH concentrations.

Combining early postoperative parathyroid hormone and serum calcium levels allows for an efficacious selective post-thyroidectomy supplementation treatment.

BACKGROUND: Optimal treatment protocol to prevent symptomatic hypocalcemia following total thyroidectomy is still matter of debate. We prospectively evaluated the efficacy of a selective supplementation protocol based on both early postoperative intact parathyroid hormone (iPTH) and serum calcium levels. METHODS: Two hundred thirty consecutive patients were divided in three different groups of treatment according to iPTH levels 4 h after total thyroidectomy (4 h-iPTH) and serum calcium levels in the first postoperative day (1PO-Ca): group A (4 h-iPTH > 10 pg/ml, 1PO-Ca ≥ 8.5 mg/dl), no treatment; group B (4 h-iPTH > 10 pg/ml, 1PO-Ca < 8.5 mg/dl), oral calcium (OC) 3 g per day; and group C (4 h-iPTH ≤ 10 pg/ml), OC 3 g + calcitriol (VD) 1 µg per day. Development of biochemical and/or symptomatic hypocalcemia was evaluated. RESULTS: Fifty-nine patients (25.6%) had subnormal 4 h-iPTH levels (≤10 pg/ml) (group C). Among patients with normal 4 h-iPTH levels, 25 (10.9%) had subnormal 1PO-Ca (<8.5 mg/dl) (group B). The remaining 146 patients (63.5%) had normal 4 h-iPTH and 1PO-Ca levels (group A). One patient in group A, 2 in group B, and 18 in group C developed biochemical hypocalcemia. Only one patient in group C experienced major symptoms. Treatment was discontinued within 1 month in all the patients in group B. At a mean follow-up of 303 days, five patients in group C were still under supplementation treatment. CONCLUSION: The proposed supplementation protocol seems efficacious in preventing symptomatic hypocalcemia. It could allow a safe and early discharge of most patients, thus avoiding the constraints and the costs of routine supplementation.

Early prediction of postthyroidectomy hypocalcemia by one single iPTH measurement.

BACKGROUND: We prospectively evaluated the possibility to make an early prediction of postthyroidectomy hypocalcemia by postoperative intact parathyroid hormone (iPTH) measurements. METHODS: Fifty-three consecutive patients who underwent bilateral thyroid resection were included; iPTH was measured preoperatively, at the end of the surgical procedure, and at 2, 4, 6, 24, and 48 hours after the operation. Patients who had hypocalcemia (serum total calcium, <8.0 mg/dL) were compared with normocalcemic patients. RESULTS: Sixteen patients experienced hypocalcemia. Six patients experienced symptoms. No significant difference was found between hypocalcemic and normocalcemic patients concerning demographic, pathologic, and preoperative laboratory data, surgical procedure, and intraoperative findings. Postoperative iPTH levels were reduced in hypocalcemic patients at the end of the procedure and at 2, 4, 6, 24, and 48 hours after the operation ( P < .001). IPTH levels below the normal range (<10 pg/mL) at 4 and 6 hours after the operation correctly predicted postoperative hypocalcemia and symptoms in all but 1 patient with a self-limiting, asymptomatic hypocalcemia (serum calcium concentration, 7.8 mg/dL) (specificity, 100%; sensitivity, 94%; overall accuracy, 98%). CONCLUSIONS: One single iPTH measurement reliably can predict, early after thyroidectomy, which patients are prone to clinically relevant postoperative hypocalcemia and necessitate supplementation treatment and which patients are eligible for a safe early discharge.