Degree of hypercalcemia correlates with parathyroidectomy but not with symptoms.

Background: Primary hyperparathyroidism (HPT) is an undertreated disease. This study's purpose is to determine if the calcium levels correlate with prevalence of symptoms and surgical treatment in patients with primary HPT.

Method: Patients treated in 2006-2015 with serum calcium≥10.0 mg/dL and PTH>65 pg/mL were identified and stratified based on calcium level: 10.0-10.3 (normocalcemia), 10.4-11.2 (moderate), and ≥11.3 (severe) mg/dL. Clinical variables and rates of surgery were compared between the three groups.

Results: A total of 2266 patients were identified: 303 with normocalcemia, 1513 with moderate hypercalcemia, and 450 with severe hypercalcemia. All three groups had similar rates of nephrolithiasis (p = 0.10), osteoporosis (p = 0.82), and reduced GFR (p = 0.06). Most patients (85%) had at least one surgical indication, but only 29% underwent parathyroidectomy. Higher calcium levels were correlated with higher surgical rates: 12% for Ca 10.0-10.3, 27% for Ca 10.4-11.2, and 46% for Ca≥11.3 (p < 0.01).

Conclusion: Prevalence of symptoms does not correlate with calcium levels. Patients with normocalcemia and moderate hypercalcemia were equally likely to have a surgical indication, but normocalcemic patients are less likely to receive surgery.