Post-surgery hormone testing may rule out permanent hypoparathyroidism
Having 2nd procedure to complete thyroid removal increased risk of complication
Written by |
Levels of parathyroid hormone (PTH) on the day after thyroidectomy – a surgery to remove the thyroid gland – may accurately help rule out permanent hypoparathyroidism, a study in Turkey suggests.
Almost 4% of nearly 500 people who underwent surgical thyroid removal developed permanent hypoparathyroidism. Having a second surgery to complete thyroid removal also increased the risk of this long-term complication, compared with total thyroidectomy in a single procedure.
“These findings underscore the value of early postoperative [PTH] monitoring and meticulous surgical technique in minimizing the risk of permanent hypoparathyroidism,” researchers wrote.
The study, “Predicting permanent hypoparathyroidism after thyroidectomy: role of early postoperative parathyroid hormone levels and surgical factors,” was published in BMC Endocrine Disorders.
Hypoparathyroidism characterized by low levels of PTH
Hypoparathyroidism is characterized by low levels of PTH, a hormone produced by the parathyroid glands located in the neck, near the thyroid. PTH helps regulate calcium and phosphorus levels in the body.
Low calcium and high phosphorus levels are hallmarks of the disease. Standard treatment of hypoparathyroidism involves supplementation with calcium and active vitamin D, which helps with the absorption of calcium in the body.
The chief cause of hypoparathyroidism is accidental damage or removal of the parathyroid glands during neck surgery, including thyroidectomy. While in most cases, hypoparathyroidism is transient, in some patients it remains permanent.
PTH level highly accurate in predicting permanent hypoparathyroidism
In this study, researchers in Turkey analyzed the incidence (new cases) of permanent hypoparathyroidism after thyroidectomy and its association with clinical and biochemical factors in 498 patients (median age 50 years, 75.5% women).
Overall, 18 patients (3.6%) were diagnosed with permanent hypoparathyroidism. It occurred more commonly in those who underwent a second surgery to remove the remaining thyroid tissue (completion surgery) than in patients who underwent only one surgery (10% vs. 3.1%).
Individuals with permanent hypoparathyroidism more frequently presented parathyroid tissue in surgical specimens (55.6% vs. 17.9%) and had significantly lower levels of calcium (8.1 vs. 8.7 mg/dL) and PTH (3.1 vs. 25.1 picograms/mL) on the day after surgery than the group that did not have permanent hypoparathyroidism.
The potential of calcium and PTH levels for predicting permanent hypoparathyroidism when measured on the first day after surgery was assessed using a statistical tool called area under the curve (AUC), where scores range from 0 to 1. The higher the AUC value, the better the ability to identify people with a condition.
PTH of 7 picograms/mL or lower showed a higher accuracy at predicting permanent hypoparathyroidism, with an AUC of 0.92, while calcium levels of 8.3 mg/dL or lower predicted the condition with an AUC of 0.79. That PTH threshold correctly predicted 86.7% of the patients with permanent hypoparathyroidism.
It also demonstrated a high negative predictive value (99.4%), “supporting its clinical utility as a reliable tool for ruling out [permanent hypoparathyroidism],” the researchers wrote.
[PTH levels] may be particularly useful for identifying patients at low risk of developing PH, supporting clinical decision-making by helping clinicians select patients who are unlikely to require prolonged calcium or active vitamin D supplementation and who may be suitable for safer early discharge and less intensive biochemical follow-up.
By comparison, first-day calcium levels of 8.3 mg/dL correctly identified 72.2% of patients who developed permanent hypoparathyroidism.
Further analysis found that having lower postoperative PTH levels increased the likelihood of permanent hypoparathyroidism by 16.6 times. Completion surgery also increased the risk by 6.14 times. No such associations were found with calcium levels after surgery or the presence of parathyroid glands in the removed tissue.
According to the researchers, these findings show that PTH levels “may be particularly useful for identifying patients at low risk of developing PH, supporting clinical decision-making by helping clinicians select patients who are unlikely to require prolonged calcium or active vitamin D supplementation and who may be suitable for safer early discharge and less intensive biochemical follow-up.”
Still, “validation in larger, prospective cohorts is warranted before the proposed thresholds and [statistical] associations are applied in clinical practice,” they noted.
Leave a comment
Fill in the required fields to post. Your email address will not be published.