**2. Parathyroidectomy rates, indications, and methods**

Parathyroidectomy was required in about 10% of patients after 10 years and 20% after 20 years in dialysis patients [8]. The parathyroidectomy rate was 8.8/1000 patient-years from 1991 to 2009 in the Swedish dialysis and transplant population [9]. A trend toward a dip in parathyroidectomy rate was found during the era of cinacalcet. This change in treatment strategy was accompanied with increased preoperative PTH levels reflecting delayed surgery and increased disease severity [10].

The overall rate of parathyroidectomy in the United States was approximately 5.4/1000 patients between 2002 and 2011. The rate decreased from 2003 (7.9/1000 patients), reached a nadir in 2005 (3.3/1000 patients), increased again through 2006 (5.4/1000 patients), and remained stable since that time. Rates of in-hospital mortality after parathyroidectomy decreased from 1.9% in 2003 to 0.8% in 2011 [11].

In-hospital mortality has seldom happened in Kaohsiung Chang Gung Memorial Hospital during 30 years in over 2000 patients undergoing parathyroidectomy plus autotransplantation for secondary hyperparathyroidism, owing to routine cardiac 2D-echography, thallium-201 myocardial imaging, and EKG examinations before surgery [12]. In recent 5 years, sestamibi parathyroid scintigraphy is also routinely performed preoperatively.

The indications for parathyroidectomy are symptoms of bone pain, skin itching, general weakness, insomnia, and soft tissue calcification with Ca levels ≥10.2 mg/dL, P levels ≥4.7 mg/dL, alkaline phosphatase (Alk-ptase) levels ≥94 IU/L, intact parathyroid hormone (iPTH) levels ≥800 pg./mL, and bone mineral density (T-score) ≤ −2.5

**101**

*Severe Hypocalcemia after Total Parathyroidectomy Plus Autotransplantation for Secondary…*

in dialysis patients. All oral medications including calcitriol, sevelamer, and cinacalcet have to be discontinued 1 month before surgery to avoid severe hypocalcemia in the

During surgery, if four or more glands and bilateral thymus are removed (total parathyroidectomy and bilateral thymectomy) (TPX & BT), l00 mg of parathyroid gland with diffuse hyperplasia is autotransplanted (AT) into the subcutaneous tissue of the forearm without harboring the arteriovenous fistula [13]. If less than four glands are found and removed, bilateral thymectomy is performed, but AT is

Previously, the critical value of hypocalcemia (CVH) was defined as Ca levels ≤6.0 mg/dL within 48 h of total parathyroidectomy, indicating the possibility of life threatening complications [14] or as profound and prolong hypocalcemia (hungry bone syndrome) with corrected serum Ca levels of ≤8.4 mg/dL lasting for 4 or more days, that occurred anytime within 1 month following the parathyroidectomy [15]. Bone hungry syndrome occurred frequently around 25–27.4% after total parathyroidectomy for secondary hyperparathyroidism [4, 15] and CVH around 15.3% [14]. In a recent study, we included 322 patients who were successfully treated with TPX & BT plus AT. They were divided into two groups. Group A (mild hypocalcemia) patients had serum Ca levels ≥6.5 mg/dL at 18 h post-operation and needed ≤4 g i.v. Ca gluconate to keep Ca levels ≥6.5 mg/dL during the post-operative period (7 days). Group B (severe hypocalcemia) patients had serum Ca levels <6.5 mg/dL at 18 h post-operation or needed >4 g of i.v. Ca gluconate during the post-operative period to keep Ca levels ≥6.5 mg/dL. Surgery was considered successful when iPTH levels were lowered to <72 pg./mL within 1 week after surgery [16]. The rate of severe hypocalcemia was 23.3% in our study. It appeared that our study included a larger sample size than previous series did [14, 15, 17–20]; thus, our results were more dependable, but a few risk factors we identified were different from those

Using the ROC curve analysis of Ca levels at 18 h post-operation for predicting hypocalcemia that needed i.v. Ca gluconate, the maximal Youden index was 0.415 and the optimal cutoff value was 7.6 mg/dL, with sensitivity of 0.72 (95% CI 0.590–0.839), specificity of 0.695 (95% CI 0.620–0.748), and area under the curve 0.749 ± 0.032 (mean ± SE) (95% CI 0.686–0.812) (**Figure 1**); patients who met this criterion should be treated with i.v. Ca gluconate. Previous reports suggested that Ca levels of 7.5–8.0 mg/dL at 18 h post-operation could predict severe hypocalcemia, and our

Preoperatively, patients were younger in Group B [50 (40–46)] [median (interquartile range)] than in Group A [58 (52–64)] (*p <* 0.001); serum P, Alk-ptase, and iPTH levels were significantly higher, but serum Ca levels were significantly lower in Group B than those in Group A (**Table 1**). Same findings were reported previously [14, 15]. There were no significant differences between the two groups in terms of sex, symptoms, body weight, and duration of dialysis (**Table 1**). The amount of blood loss during surgery was not significantly different between the two groups. The operation time, total weight of removed parathyroid glands, duration of post-operative hospitalization (days), and total amount of i.v. Ca gluconate administered were significantly more, but calcium levels at 18 h post-operation were significantly lower in Group B than in Group A (*p* = 0.014, *p* = 0.035,

*p* < 0.001, *p* < 0.001, and *p* < 0.001, respectively) (**Table 2**).

**3. Definition of severe hypocalcemia post-parathyroidectomy** 

*DOI: http://dx.doi.org/10.5772/intechopen.92976*

post-operation period.

**and risk factors**

reported previously.

results support this finding [18, 20].

omitted.

*Severe Hypocalcemia after Total Parathyroidectomy Plus Autotransplantation for Secondary… DOI: http://dx.doi.org/10.5772/intechopen.92976*

in dialysis patients. All oral medications including calcitriol, sevelamer, and cinacalcet have to be discontinued 1 month before surgery to avoid severe hypocalcemia in the post-operation period.

During surgery, if four or more glands and bilateral thymus are removed (total parathyroidectomy and bilateral thymectomy) (TPX & BT), l00 mg of parathyroid gland with diffuse hyperplasia is autotransplanted (AT) into the subcutaneous tissue of the forearm without harboring the arteriovenous fistula [13]. If less than four glands are found and removed, bilateral thymectomy is performed, but AT is omitted.
