SAT-521 Changes in Multiple Bone Metabolism Markers after Adrenalectomy in Patients with Aldosterone Producing Adenoma

<Background > In primary aldosteronism (PA), it is reported that secondary hyperparathyroidism (SHPT) is caused by increased urinary Ca excretion due to excessive aldosterone, which may decrease bone mineral density and increase fracture risk. However, there have been few reports that evaluated changes in bone metabolism markers in detail before and after the treatment for PA. In this retrospective study, we evaluated changes in multiple bone metabolism markers before and after adrenalectomy. <Methods> We analyzed 16 patients who underwent adrenalectomy for unilateral aldosterone-producing adenoma (APA) in our hospital from April 2009 to November 2017 and compared various bone metabolism markers before and after surgery. All patients were diagnosed with unilateral hyperaldosteronism by segmental adrenal venous sampling. Patients with bilateral hyperaldosteronism and bone disease were excluded. We compared changes in levels of serum Ca, 24-hour urinary Ca excretion (u-Ca), intact parathyroid hormone (iPTH), tartrate-resistant acid phosphatase 5b (TRACP-b5), bone-specific alkaline phosphatase (BAP), and undercarboxylated osteocalcin (ucOC) before and one year after surgery. <Results> Sixteen patients consisted of 8 males and 8 females (Mean age =49.6 years old, BMI =23.7 kg/m(2), hypertension duration =10.9 years, blood pressure =135/84 mmHg, eGFR =86.6 mL/min/1.73 m(2)). After surgery, aldosterone hypersecretion improved markedly (plasma aldosterone (PAC); 278.4 ± 167.5 to 96.9 ± 47.1 pg/mL, urinary aldosterone; 28.6 ± 22.7 to 5.6 ± 3.9 μg/day). Significant increase in serum Ca (8.74 ± 0.24 to 9.31 ± 0.80 mg/dL, P < 0.001) and decreases in u-Ca (0.23 ± 0.10 to 0.09 ± 0.07 g/day, P = 0.002) and iPTH (86.7 ± 40.8 to 54.4 ±16.3 pg/mL, P < 0.001) were observed. In addition, significant decreases in TRACP-b5 (373.0 ± 180.1 to 211.9 ± 101.2 mU/dL, P < 0.001), BAP (16.6 ± 7.06 to 10.8 ± 3.73 μg/L, P < 0.001), and ucOC (7.56 ± 5.0 to 4.04 ± 2.3 ng/mL, P = 0.004) levels were observed. The change in iPTH had significant positive correlation with the change in PAC (r = 0.55, P = 0.026), while it had no correlation with the change in u-Ca. <Conclusion> The correction of hyperaldosteronism by adrenalectomy decreased urinary Ca excretion, iPTH level, and bone tune over. In addition, our results suggest that the increase in iPTH was caused by hyperaldosteronism, independent from the excess in urinary calcium excretion.