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 ($\ge$ 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.