Hypocalcemia After Thyroidectomy in Patients with Prior Bariatric Surgery: A Propensity Score Matched Analysis from a National Administrative Database

Hungry bone syndrome following thyroid surgery

The diagnosis of hypocalcemia-induced tetany following a total thyroidectomy is not common. However, there is a higher risk in patients with a history of gastric bypass surgery due to their malabsorption condition. This case describes postoperative hungry bone syndrome resulting from chronic malabsorption in a patient with a history of bariatric surgery. It is important to consider alternative treatment options if the initial management proves ineffective. Typically, this is a temporary condition, but it's crucial to prioritize prevention in high-risk patients by providing perioperative calcium and vitamin D supplementation.

History of Bariatric Surgery Before Thyroid Surgery: Recommendations for Prevention and Management of Postoperative Hypocalcemia

Hypocalcemia following thyroidectomy is a common and potentially life-threatening complication. It is caused by intraoperative injury to the parathyroid glands or their blood supply. Although several studies have shown that patients with a prior history of bariatric surgery may be at an increased risk for hypocalcemia after thyroidectomy, no clear recommendations exist for preventing and managing this condition in this population. This paper highlights the significance of understanding this risk and of obtaining a history of prior bariatric surgery before thyroidectomy. We propose concise recommendations for preventing and managing hypocalcemia following thyroidectomy in patients with a history of bariatric surgery.

Hypovitaminosis D and hyperparathyroidism: a 5-year postoperative follow-up of 30,458 gastric bypass and sleeve gastrectomy patients

BACKGROUND

Bariatric procedures are associated with nutrient deficiencies. Studies show an association between gastric bypass (Roux-en-Y gastric bypass [RYGB]) and hypovitaminosis D as well as hyperparathyroidism, yet few compare RYGB to sleeve gastrectomy (SG), and large long-term analyses are scarce.

OBJECTIVE

Evaluate trends of vitamin D and parathyroid hormone (PTH) levels in RYGB and SG.

SETTING

National quality register.

METHOD

The Scandinavian Obesity Surgery Registry records all bariatric surgeries in Sweden. Data from 2008 to 2021 on primary RYGB or SG with reported 25-hydroxy vitamin D (25-OH-D) and/or PTH levels were included. Individuals with an estimated glomerular filtration rate of <60 mL/min/1.73 m2 were excluded, leaving a study population of 25,385 RYGB and 5073 SG patients.

RESULTS

A decrease in 25-OH-D, mirrored by an increase in PTH, was observed after the first year for both procedures, but more pronounced in RYGB. At 5 years, 25-OH-D levels were still higher than at baseline. Regular supplementation resulted in better 25-OH-D and PTH levels. Linear regression found that procedure type (RYGB versus SG), 25-OH-D levels, and time since surgery were significant factors in predicting PTH levels. The risk of pathologic PTH levels (>7 pmol/L) at 2 and 5 years postoperatively was roughly three times higher in RYGB (odds ratios = 3.41 and 2.84, respectively).

CONCLUSIONS

Previous studies alongside these results suggest that RYGB, more so than SG, may cause hypovitaminosis D and thereby hyperparathyroidism, which could lead to osteopenia. The threshold for 25-OH-D should be >75 nmol/L, and despite higher levels, current vitamin D supplementation may not be sufficient. Follow-up should include screening for hyperparathyroidism and hypovitaminosis D.

Hypocalcemia after parathyroidectomy in patients with a history of bariatric surgery

PURPOSE

A growing body of literature has suggested that a history of bariatric surgery increases the risk of hypocalcemia after subsequent thyroidectomy, however little is known about the risk after parathyroidectomy. The purpose of this study was to determine the incidence of hypocalcemia after parathyroidectomy in patients with prior bariatric surgery.

METHODS

The TriNetX Research Network was queried using diagnosis and procedure codes to identify patients with a history of bariatric surgery who were subsequently diagnosed with primary hyperparathyroidism (PHP) and underwent parathyroidectomy between 2012 and 2022. The rate of hypocalcemia after parathyroidectomy was compared between those with a history of bariatric surgery and controls who underwent parathyroidectomy alone, matched for demographics, body mass index (BMI) ≥ 30 kg/m², and history of calcium or vitamin D supplementation.

RESULTS

There were 34,483 included patients diagnosed with PHP who underwent parathyroidectomy. Of this cohort, 1.4% (n = 472) had prior bariatric surgery. There were 90% females and 10% males in this subset of patients, and the average age was 58 years. Compared to matched controls who underwent parathyroidectomy alone, these patients had a significantly increased risk of hypocalcemia within 0-1 month (RR, 95% CI, P) (17.2% vs. 9.3%; 1.8, 1.3-2.6, P < 0.001), 1-6 months (8.5% vs. 2.5%; 3.3, 1.8-6.3, P < 0.001) and 6-12 months (6.8% vs. 2.3%; 2.9, 1.5-5.7, P < 0.001) following surgery.

CONCLUSION

The current study is the first to indicate that patients with a history of bariatric surgery are at increased risk for short-term and permanent hypocalcemia after parathyroidectomy. Further research is required to determine optimal prevention and treatment strategies to decrease associated morbidity in this subset of patients.