Risk factors and evolution of calcium and parathyroid hormone levels in hungry bone syndrome after parthyroidectomy for primary hyperparathyroidism

Hungry bone syndrome following parathyroidectomy for primary hyperparathyroidism in a developed country in the Asia Pacific. A cohort study

Objectives

We sought to assess the incidence of hungry bone syndrome (HBS) following parathyroidectomy (PTX) for primary hyperparathyroidism (PHPT) in a cohort of multi-ethnic patients from a developed country in the Asia Pacific.

Methods

One hundred and sixty-four patients who underwent PTX for PHPT between 2012 and 2019 at the 2 largest public hospitals in Singapore were identified. HBS was defined as serum albumin-adjusted calcium ≤ 2.1 mmol/L with normal or raised serum intact parathyroid hormone (iPTH) levels, manifesting on or after the 3rd day, or persisting for more than 3 days post-operatively.

Results

Chinese constituted 73.8%, Malays 12.2%, Indians 9.8%, and other races 4.3%. HBS developed in 4 patients (2.4%) (95% CI, 0.8%–6.5%). HBS patients had significantly longer in-hospital stays; 20 days [IQR:15–22] vs 2 days [IQR:1–3]; P < 0.001in those who did not develop HBS. There was no difference in the incidence of HBS stratifying for age, sex, vitamin D status, or use of preoperative anti-resorptive medication use. For every 10 unit increase in iPTH and alkaline phosphatase (ALP) levels, the risk of HBS increased by 14% and 11%; RR (95% CI), 1.14 (1.05–1.21) and 1.11 (1.03–1.18), respectively.

Conclusions

The low incidence of HBS in multi-ethnic patients undergoing PTX by multiple surgeons for PHPT at the 2 largest public hospitals that see the most such patients in Singapore, a developed country, is consistent with the asymptomatic/milder form of presentation of PHPT in the developed world.

Risk Factors for Prolonged Length of Stay and Readmission After Parathyroidectomy for Renal Secondary Hyperparathyroidism

BACKGROUND

Population-based analyses of 30-day outcomes after parathyroidectomy for renal secondary hyperparathyroidism are limited. We sought to identify risk factors associated with prolonged length of stay (LOS) and readmission in this patient population.

METHODS

Patients with secondary hyperparathyroidism who underwent parathyroidectomy were reviewed in the ACS-NSQIP database (2011-2016). Patients were identified by ICD codes specific to secondary hyperparathyroidism of renal origin and the ACS-NSQIP variable for current preoperative dialysis. Multivariable logistic regression was used to identify independent factors associated with prolonged LOS and 30-day readmission after parathyroidectomy.

RESULTS

The cohort included 1846 patients with secondary hyperparathyroidism on dialysis who underwent parathyroidectomy. There were 416 (22.5%) patients classified under the prolonged LOS group. On multivariable analysis, factors associated with prolonged LOS included elevated preoperative alkaline phosphatase [OR 3.13 (95%-CI 2.09-4.70), p < 0.001], decreased preoperative hematocrit [OR 1.83 (95%-CI 1.25-2.68), p = 0.002], unplanned reoperation (OR 5.02 [95%-CI 2.22-11.3], p < 0.001) and any postoperative complication [OR 6.12 (95%-CI 3.31-11.3), p < 0.001]. The overall 30-day readmission rate was 15.0%. Hypocalcemia and hungry bone syndrome accounted for 47.0% (n = 93/198) of readmissions. On multivariable analysis, patients with a history of hypertension and those undergoing unplanned reoperation were at risk of readmission [2.16 (95%-CI 1.21-3.87), p = 0.009, and 2.40 (95%-CI 1.15-5.02), p = 0.020, respectively], whereas reoperative parathyroidectomy was inversely associated with readmission (OR 0.24, 95%-CI 0.07-0.80, p = 0.021).

CONCLUSION

In patients undergoing parathyroidectomy for renal secondary hyperparathyroidism, several readily available preoperative biochemical markers, including those of increased bone turnover and anemia, are associated with prolonged postoperative LOS. Unplanned reoperation was predictive of both increased LOS and readmission.