Abstract
Introduction
The mainstay of treatment for primary hyperparathyroidism is surgery. Hypocalcemia after parathyroidectomy is common and poses a significant challenge, leading to increased patient morbidity and health care costs. While several groups have found predictor factors for hypocalcemia, none have created a risk stratification model. Here, we recognize important factors and optimal cut-off values that can allow risk stratification of patients.
Methods
A single-institution retrospective chart review of 339 patients that underwent parathyroidectomy from 2009 to 2012 was conducted. Pre-operative, intra-operative, and post-operative data were collected. A non-routine outcome was defined as post-operative admission, outpatient hypocalcemia-related complication, or inpatient hypocalcemia-related complication. The preoperative or intraoperative factors of patients that experienced a non-routine outcome were compared to those that did not. Optimal cut-off values were determined for preoperative and intraoperative factors and a risk stratification method was created.
Results
A total of 39 patients experienced a non-routine outcome including 24 postoperative admissions, 2 inpatient hypocalcemia-related complications, and 17 outpatient hypocalcemia-related complications. Patients with a non-routine outcome displayed a trend toward preoperative hypercalcemia (calcium >11.0 mg/dL) than not (p = 0.0543). The median preoperative parathyroid hormone (PTH) level was significantly higher among patients with a non-routine outcome (p = 0.0037). Furthermore, the median percent decrease in PTH at 20 min intraoperatively among patients with a non-routine outcome was significantly higher compared to those that did not (p = 0.0421). The optimal cut-off value for preoperative PTH was 129 pg/mL and for median percent decrease in intraoperative PTH at 20 min was 90.7% for predicting a non-routine outcome. A risk stratification model was created based on these data.
Conclusion
Our analysis reveals that patients with larger intraoperative decrease in PTH levels (greater than 90.7% drop at 20 min), higher preoperative hypercalcemia (greater than 11 mg/dL), and higher preoperative PTH levels (greater than 129 pg/mL) are more likely to experience a non-routine outcome during outpatient parathyroidectomy. Patients can be risk stratified based on this criteria.
1
Introduction
Primary hyperparathyroidism is the third most common endocrine disorder, frequently diagnosed in postmenopausal women . It is characterized by excess production and secretion of parathyroid hormone by one or more parathyroid glands, and is attributed to a single parathyroid adenoma in 75–85% of cases . Less commonly, hyperplasia of one or more of the glands or parathyroid cancer can cause hyperparathyroidism .
For symptomatic patients and those asymptomatic patients that meet specific criteria, the mainstay of treatment for primary hyperparathyroidism is parathyroidectomy of one or more of the glands . The abnormal gland can be localized preoperatively via ultrasonography, nuclear studies, computed tomography (CT) scan, or magnetic resonance imaging (MRI). Intraoperative localization methods can also help identify the parathyroid glands .
Hypocalcemia, either transient or persistent, is a common postoperative complication of parathyroidectomy and remains a substantial challenge. Transient hypocalcemia can result in neuromuscular irritability, exhibited by tetany, numbness, perioral and digital paresthesias, and muscular spasms. In severe cases, stridor, bronchospasm, cardiac arrhythmias, angina, cardiac failure, syncope, and seizures may result . Chronic states of hypocalcemia may be asymptomatic or manifest as cataracts, dry skin, brittle nails and poor dentition. Transient hypocalcemia has been reported to occur in 0–35% of parathyroidectomy cases, whereas persistent hypocalcemia has been reported in 0–3.8% of cases .
While the use of surgical techniques such as minimally invasive parathyroidectomy and video-assisted parathyroidectomy have reduced the incidence of hypocalcemia from 46% to 10%, the adverse events that still occur threaten the safety of patients postoperatively, especially those that undergo same-day surgery. This study aims to define predictive factors for the onset of postoperative hypocalcemia after parathyroidectomy. While multiple studies have identified such factors, none have defined specific cut-off values or risk stratification models for these predictive factors. By identifying risk factors and cut-off values, we created a risk stratification model to identify patients at higher risk for post-operative hypercalcemia that require inpatient or outpatient monitoring.
2
Methods
This study was reviewed by the Institutional Review Board (IRB) of the Icahn School of Medicine at Mount Sinai and certified as IRB exempt. We retrospectively analyzed the medical records of 339 patients that underwent parathyroidectomy at our institution from 2009 to 2012.
All except fourteen patients had pre-operative imaging, ranging from a Sestamibi scan, thyroid ultrasound, computed tomography (CT) of the neck, or magnetic resonance imaging (MRI) of the neck. All surgeries were performed by one of four surgeons in the department of otolaryngology who are fellowship-trained in head and neck surgery.
Data collected from these records are shown in Table 1 .
| Patient demographics | Age |
|---|---|
| Gender | |
| Preoperative factors | Renal insufficiency |
| Hypercalcemia | |
| Urinary calcium level | |
| PTH level | |
| Alkaline phosphatase level | |
| High alkaline phosphatase | |
| 1,25-dihydroxycholecalciferol level | |
| 25-dihydroxycholecalciferol level | |
| Low vitamin D | |
| Osteopenia | |
| Osteoporosis | |
| Normal DEXA scan | |
| T-score < 2.5 SD on DEXA scan | |
| Age < 50 years | |
| Intraoperative factors | PTH at baseline |
| PTH at 5 min | |
| PTH at 10 min | |
| PTH at 20 min | |
| % drop from baseline at 20 min | |
| Surgery characteristics | Laterality of exploration |
| Number of glands excised | |
| Reimplantation performed | |
| Surgical outcomes | Postoperative admission |
| Inpatient hypocalcemia-related complication | |
| Outpatient hypocalcemia-related complication | |
| Unrelated complication |
A non-routine outcome was defined as postoperative admission, outpatient hypocalcemia-related complication, and/or inpatient hypocalcemia-related complication. A patient that experienced more than one of these was considered only once in the analysis. A routine outcome was defined as none of the above. The Statistical Analysis System was used for analysis in order to find significant difference in preoperative or intraoperative factors in those patients that experienced a non-routine outcome compared to those that did not. For those factors that were significant, a cut-off analysis was performed where the optimal cut-off value was defined as the value of the predictor for which the sensitivity and specificity are the highest. The ideal value has 100% sensitivity and 100% specificity.
2
Methods
This study was reviewed by the Institutional Review Board (IRB) of the Icahn School of Medicine at Mount Sinai and certified as IRB exempt. We retrospectively analyzed the medical records of 339 patients that underwent parathyroidectomy at our institution from 2009 to 2012.
All except fourteen patients had pre-operative imaging, ranging from a Sestamibi scan, thyroid ultrasound, computed tomography (CT) of the neck, or magnetic resonance imaging (MRI) of the neck. All surgeries were performed by one of four surgeons in the department of otolaryngology who are fellowship-trained in head and neck surgery.
Data collected from these records are shown in Table 1 .
| Patient demographics | Age |
|---|---|
| Gender | |
| Preoperative factors | Renal insufficiency |
| Hypercalcemia | |
| Urinary calcium level | |
| PTH level | |
| Alkaline phosphatase level | |
| High alkaline phosphatase | |
| 1,25-dihydroxycholecalciferol level | |
| 25-dihydroxycholecalciferol level | |
| Low vitamin D | |
| Osteopenia | |
| Osteoporosis | |
| Normal DEXA scan | |
| T-score < 2.5 SD on DEXA scan | |
| Age < 50 years | |
| Intraoperative factors | PTH at baseline |
| PTH at 5 min | |
| PTH at 10 min | |
| PTH at 20 min | |
| % drop from baseline at 20 min | |
| Surgery characteristics | Laterality of exploration |
| Number of glands excised | |
| Reimplantation performed | |
| Surgical outcomes | Postoperative admission |
| Inpatient hypocalcemia-related complication | |
| Outpatient hypocalcemia-related complication | |
| Unrelated complication |
A non-routine outcome was defined as postoperative admission, outpatient hypocalcemia-related complication, and/or inpatient hypocalcemia-related complication. A patient that experienced more than one of these was considered only once in the analysis. A routine outcome was defined as none of the above. The Statistical Analysis System was used for analysis in order to find significant difference in preoperative or intraoperative factors in those patients that experienced a non-routine outcome compared to those that did not. For those factors that were significant, a cut-off analysis was performed where the optimal cut-off value was defined as the value of the predictor for which the sensitivity and specificity are the highest. The ideal value has 100% sensitivity and 100% specificity.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
