Regarding calcium and vitamin D intake for patients with asymptomatic PHPT, studies have shown that there is no indication for dietary calcium restriction; 800–1000 mg daily dietary calcium intake is recommended, but less may be considered in patients with hypercalciuria [15]. In addition, vitamin D-deficient patients with PHPT have been shown to have higher levels of PTH, markers of bone turnover, and more frequent fractures than vitamin D-replete patients [14]. Vitamin D repletion in patients with PHPT doesn’t exacerbate hypercalcemia and low serum 25-hydroxyvitamin D should be replaced with vitamin D supplementation aiming to bring the serum 25-hydroxyvitamin D levels to the level of at least 20 ng/mL [8, 16].

In this case, a DXA BMD revealed osteopenia at the total hip and femur neck with T-scores of −1.1 and −1.5, respectively, well-preserved bone density at the lumbar spine with a T-score of −0.1, and a nondominant left one-third radius T-score of −0.9. Spine radiographs did not reveal compressive fractures. Her 10-year risks for a major osteoporotic fracture and hip fracture were 10 % and 1.5 %, respectively. Imaging of her kidneys was negative for urinary calculi. Her 25-hydroxyvitamin D deficiency level was sufficient. A 24-h urine calcium was 135 mg with a fractional excretion of filtered calcium of 0.014, which in conjunction with a negative family history of hypercalcemia made FHH unlikely.

After completion of the initial evaluation, the patient was seen for follow-up to determine management of her mild and uncomplicated PHPT. The natural history of mild PHPT suggests that progression can occur, such that by 15 years of prospective follow-up, as many as one-third of subjects will demonstrate more overt features of the disease (e.g., kidney stones, worsening hypercalcemia, and reduced BMD) [17]. Hence, surgery should be considered in patients for whom medical surveillance is not desired. In addition, compared to observation, successful parathyroid surgery is associated with spine and hip bone density improvement [18], reduced rate of nephrolithiasis among those with a history of renal stone disease [19], and there may be improvement in some neurocognitive elements [20–22]. In these cases, an informed discussion needs to be had and patient’s preference is pivotal for a shared decision-making approach. With advances in the effectiveness and safety of surgical techniques, particularly in the hands of expert parathyroid surgeons [23, 24], the decision to remove the abnormal parathyroid tissue is often reinforced by the added confidence of its success and limited risk of postoperative complications.

Given the patient’s ongoing symptoms of lower extremity pain as well as concern of long-term complications and progression of PHPT, she elected to consider parathyroid surgery and meet with an experienced endocrine surgeon. A parathyroid scan was subsequently performed, but was non-localizing. After her appointment with the surgeon, she elected to observe, rather to proceed with parathyroidectomy. Asymptomatic patients who do not undergo surgery require monitoring for worsening hypercalcemia, renal impairment, and bone loss. The development of any of these findings may indicate disease progression and the reconsideration of surgical intervention. The Fourth International Workshop [13] recommendations for monitoring asymptomatic PHPT are outlined in Table 1.2.