PTH Levels in Children Soon After Surgery Show Risk of Hypocalcemia

Assessing parathyroid hormone (PTH) levels in children after surgery to remove the thyroid and initiating preventive therapy for people at high risk for hypocalcemia, increased safety and shortened their hospital stay, a study reported.

Hypocalcemia, or potentially harmful low calcium levels, is a common complication of surgery to remove the thyroid gland, known as a thyroidectomy.

The study, “Improving Safety in Pediatric Thyroidectomy by PTH Measurements,” was published in the journal Clinical Endocrinology.

Hypocalcemia after thyroidectomy can cause muscle cramps, pain, weakness, spasms, and confusion. It occurs in an estimated 26% to 63% of pediatric patients after this surgery.

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Although usually temporary, hypocalcemia can extend a patient’s hospital stay and require frequent blood samples to monitor calcium levels. When these levels drop, calcium supplements can be given.

However, only treating all patients preventively with calcium supplements is complicated by the risk of hypercalcaemia, or too much calcium in the blood. Hypercalcemia can also cause a range of symptoms, including nausea, bone pain, muscle weakness, confusion, and fatigue.

Researchers from the Hospital de Niños Dr. Ricardo Gutiérrez, in Buenos Aires, Argentina, have established a cut-off for PTH that could predict hypocalcemia in hpyoparathyroidism with an estimated sensitivity of 93% (percent of true positives) and 100% specificity (percent of true negatives) by two PTH measurements, taken five minutes and 60 minutes after thyroid removal.

Patients who are at high risk by this measurement can then be treated preventively for hypocalcemia with calcium and vitamin D supplements, while patients at low risk can undergo 48 hours of calcium level monitoring, alerting both patients and parents to the symptoms of the disease. hypocalcemia.

Based on this cut-off, the Hospital de Niños team conducted a study to test whether their approach could reduce the incidence of hypocalcemia and the length of hospitalizations for high-risk children and teens with hypoparathyroidism. They also examined the safety of taking fewer blood draws to measure calcium in low-risk patients.

As a control group, the researchers compared their results with data from 32 previous cases with equivalent PTH measurements; all patients in this group were treated for hypocalcemia after they began to show symptoms.

The scientists recruited 66 patients (52 women) ages 2 to 19 for their study. These pediatric patients were categorized as high risk if their PTH level five minutes after surgery (PTH-5) did not exceed 1.6 picomole(pmol)/L, or if their PTH-5 was between 1.6 and 2 pmol /L and their PTH after 60 minutes was not more than 1.6 pmol/L.

Based on this cut-off, 30 patients were considered high risk and started intravenous (into the vein) calcium supplementation immediately after surgery. Five of them (17%) developed hypocalcemia, as did all 14 control patients predicted to be at high risk.

Calcitriol, a form of vitamin D3, was added to their treatment schedule 24 hours after starting calcium.

The hospital stay for these patients averaged three days, compared to six days for controls.

The 36 low-risk participants had significantly fewer calcium samples over a 48-hour period after surgery compared to the control group. Eight (22%) developed hypocalcemia and their median hospital stay was six days, comparable to controls.

Overall, hypocalcemia occurred in 20% of the total study group and 47% of the control group, for a 58% overall reduction in hypocalcemia.

“Start Intravenous” [calcium] and calcitriol supplementation before the onset of hypocalcemia was likely the intervention leading to shorter hospital stays” in high-risk pediatric patients, the researchers wrote.

Of the 25 children whose thyroidectomy resulted from thyroid cancer, lymph nodes and surrounding neck tissue were also removed, and 21 showed an increased risk of hypoparathyroidism or hypocalcemia, the researchers noted.

“We believe,” they wrote, “that these patients do not benefit from intra- or postoperative PTH determinations, and that early preventive perioperative [around the time of surgery] treatment of hypocalcaemia with intravenous [calcium] and calcitriol supplementation” is appropriate.

“Undoubtedly, our strategy improves the postoperative safety of children and adolescents undergoing thyroidectomy, and it is cost-effective,” the team added.

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