Pam Harrison

June 16, 2015

LONDON, United Kingdom — For kidney transplant recipients with hypercalcemia related to hyperparathyroidism, parathyroidectomy is superior to cinacalcet (Sensipar, Amgen), a comparative study indicates.

"Inappropriately high parathyroid hormone levels are associated with hypercalcemia, hyperphosphatemia, both allograft and vascular calcification, and bone mineral density loss," said Josep Cruzado, MD, from Bellvitge University Hospital in l'Hospitalet de Llobregat, Spain.

"We believed that parathyroidectomy was at least as effective as cinacalcet to control hypercalcemia," he told Medscape Medical News in an email. "The main difference between the two is that parathyroidectomy may be curative whereas treatment with cinacalcet has to be maintained over time."

"Our results suggest that in renal allograft recipients with hypercalcemia due to persistent hyperparathyroidism, parathyroidectomy should be the first-line treatment of choice," he added. "Cinacalcet should be reserved for patients in whom there is a surgical contraindication."

He presented the study results here at the European Renal Association–European Dialysis and Transplant Association 52nd Congress.

Of the 30 study participants with hypercalcemia due to hyperparathyroidism, half were randomized to subtotal parathyroidectomy and the other half to cinacalcet. The average time to randomization after transplantation was 45 months in both groups.

All patients had baseline intact parathyroid hormone levels of at least 15 pmol/L, baseline serum calcium levels of at least 2.63 mmol/L, and baseline serum phosphate levels of at least 1.2 mmol/L.

The decline in intact parathyroid levels was evident 10 minutes after surgery, when levels were 75% to 98% of baseline levels (P < .0001).

At 12 months, more patients in the surgery group than in the cinacalcet group achieved normal — below 2.55 mmol/L — calcium levels (100% vs 67%; P = .04).

The number of patients with serum phosphate levels in the normal range, from 0.85 to 1.5 mmol/L, at 12 months was similar in the surgery and cinacalcet groups (15 vs 14).

Increases in serum calcidiol at 12 months were greater in the surgery group than in the cinacalcet group.

The increases in vitamin D seen after parathyroidectomy could be related to the fact that patients in the surgery group received calcium and vitamin D supplements to prevent "hungry bone" syndrome, Dr Cruzado reported.

Of note, bone mineral density at multiple sites increased significantly after parathyroidectomy, but decreased in the cinacalcet group.

For example, at 12 months, the change in bone mineral density in the femoral neck was beneficial in the surgery group but not in the cinacalcet group (3.8% vs –3.0%). The same pattern was observed in the lumbar spine (2.7% vs –0.9%).

The cost of treatment was higher in the surgery group than in the cinacalcet group (€3700 vs €3200 per patient, or about US$4200 vs US$3600). However, "if treatment duration reached at least 14 months, parathyroidectomy would be considered superior in terms of cost-effectiveness," Dr Cruzado explained.

Confirmatory Results

This study confirms that patients undergoing parathyroidectomy have significantly enhanced normalization of parathyroid and phosphate levels, compared with those who are treated medically, said Thomas Fahey, MD, from the Weill Cornell Medical College in New York City.

"Calcium levels were also lower, although only significantly so at the 6-month time point," Dr Fahey told Medscape Medical News in an email.

He explained that the results are "not surprising," given recent observations from his own group, among others, indicating that patients with primary hyperparathyroidism have significantly more normalization of parathyroid and calcium levels after parathyroidectomy (Ann Surg. 2012;255:981-985).

In addition, "renal function was better preserved in patients who underwent surgical treatment," Dr Fahey pointed out.

"And this makes sense," he said. "The better the control of parathyroid and electrolyte abnormalities, the better the outcome of functional parameters."

Dr Fahey cautioned that these results do not necessarily mean that surgery is universally better for patients with primary or tertiary hyperparathyroidism. "But it does focus attention on patients who are not achieving an optimal response to medical treatment," he said.

"At the very least, the study supports our own observation that if there is inadequate normalization of parathyroid, calcium, and phosphate levels with medical management, then consideration should be given to surgical treatment," he explained.

Dr Fahey suggested that larger prospective studies are needed to define whether there is ever a role for the medical management of patients such as those involved in this study.

This study was funded by the Spanish government. Dr Cruzado and Dr Fahey have disclosed no relevant financial relationships.

European Renal Association–European Dialysis and Transplant Association (ERA-EDTA) 52nd Congress: Abstract SaO029. Presented May 30, 2015.

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