A thorough evaluation for primary hyperparathyroidism: More than a stone's throw away.

Background: Primary hyperparathyroidism (PHPT) is a treatable cause of nephrolithiasis. However, PHPT is not consistently evaluated in nephrolithiasis patients. Symptoms of parathyroid disease were explored in relation to evaluation of PHPT in nephrolithiasis patients.

Methods: Patients with nephrolithiasis on imaging between 2017 and 2021 were identified. Measurement of serum calcium levels after nephrolithiasis diagnosis was determined. Patients with hypercalcemia (≥ 10.2 ​mg/dL) were identified. Characteristics associated with parathyroid hormone (PTH) evaluation and specialist referral were assessed.

Results: Of 2264 nephrolithiasis patients with calcium levels measured, 383 (17.1 ​%) had hypercalcemia. Of those, 107 (27.9 ​%) had PTH levels drawn. PTH was more often assessed in patients with higher median calcium levels, recurrent nephrolithiasis, depression, and osteopenia/osteoporosis. PTH was elevated (>64 ​pg/mL) or non-suppressed (40-64 ​pg/mL) in 68 (63.6 ​%) patients. Of those, 31 (45.6 ​%) were referred to a parathyroid specialist. Referred patients had higher PTH and calcium levels than those without referral, and higher rates of osteopenia/osteoporosis.

Conclusions: PTH evaluation in hypercalcemic nephrolithiasis patients was low. The majority of patients evaluated had elevated or non-suppressed PTH levels, but only a fraction were referred to a specialist.