Risk Factors for Post-TPTx Severe Hypocalcemia Identified

Study implicates male sex and higher preoperative levels of parathyroid hormone and alkaline phosphatase.
Study implicates male sex and higher preoperative levels of parathyroid hormone and alkaline phosphatase.

Chinese researchers have identified independent risk factors associated with severe hypocalcemia or “hungry bone syndrome,” following total parathyroidectomy without autotransplantation (TPTx).

Yao Lu, MD, and colleagues of China-Japan Friendship Hospital in Beijing, performed a retrospective review of medical data for 157 patients with refractory secondary hyperparathyroidism (SHPT) who underwent TPTx at the hospital during 2012 to 2015. Using their hospital's definition of critical value of hypocalcemia (CVH)—serum calcium at or below 1.5 mmol/L or 6 mg/dL at 48 hours after TPTx—they divided patients into CVH and non-CVH groups. CVH status signaled immediate care to avoid life-threatening conditions such as laryngeal stridor, seizure, cardiac arrhythmia, congestive heart failure, and tetany.

According to results published in Renal Failure (2016;38:1224-1227),some degree of hypocalcemia (serum calcium below 2 mmol/L or 8 mg/dL) developed in 77% of patients, with 15.3% exhibiting severe hypocalcemia. About 10% of CVH patients experienced life-threatening symptoms such as dyspnea and tetany.

Using logistic regression, the investigators identified male sex and higher levels of parathyroid hormone (PTH) and alkaline phosphatase as significant, independent risk factors for severe hypocalcemia at 48 hours after surgery..

Men may have greater bone formation than women and therefore more hypocalcemia, the researchers suggested. High, preoperative ALP meanwhile indicates greater osteoblastic activity, which can upset the balance of bone metabolism immediately after surgery. Elevated preoperative PTH is a known harbinger of severe SHPT and bone disease.

“Patients with such risk factors should be given a more aggressive perioperative management protocol,” Dr Lu and colleagues concluded. “We suggest that aggressive calcium infusion in the early postoperative stage after TPTx for high-risk patients is a useful method to prevent CVH.”

Univariate analysis showed that CVH patients also were significantly younger. A 2012 study by Melanie Goldfarb and colleagues  likewise identified patient age 45 and youngeras the only risk factor for hungry bone syndrome (World J Surg. 2012;36:1314–1319). Stronger osteoblast activity during the younger years possibly explains this finding. However, as another study found older age was a risk factor, larger studies are needed.

 

Source

1. Yang M, Zhang L, Huang L, Sun X, Ji H, and Lu Y. Factors predictive of critical value of hypocalcemia after total parathyroidectomy without autotransplantation in patients with secondary hyperparathyroidism. Ren Fail. 2016 Sep;38(8):1224-7. doi: 10.1080/0886022X.2016.1202731.

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