What is the diagnosis and recommended management for a patient with an intact parathyroid hormone level of 96 pg/mL and a serum calcium of 10.6 mg/dL?

Primary Hyperparathyroidism – Proceed to Surgical Evaluation

With a PTH of 96 pg/mL and calcium of 10.6 mg/dL, this patient has primary hyperparathyroidism and should be referred to both an endocrinologist and an experienced parathyroid surgeon for evaluation of surgical candidacy, as the calcium exceeds 10.2 mg/dL (the threshold for hypercalcemia) and parathyroidectomy is the only curative treatment. 1, 2

Diagnostic Confirmation

This biochemical pattern—elevated PTH with hypercalcemia—definitively establishes primary hyperparathyroidism (PHPT). 1, 2

• Calcium 10.6 mg/dL exceeds the hypercalcemia threshold of 10.2 mg/dL, confirming abnormal calcium homeostasis 2, 3
• PTH 96 pg/mL is inappropriately elevated for the degree of hypercalcemia; in normal physiology, hypercalcemia should suppress PTH to low-normal or undetectable levels 1, 2
• The parathyroid glands are autonomously secreting PTH despite elevated calcium, which is the hallmark of PHPT 2

Before finalizing the diagnosis, complete the initial workup by measuring 25-hydroxyvitamin D, serum phosphorus, creatinine with eGFR, and 24-hour urine calcium (or spot urine calcium/creatinine ratio) to exclude secondary causes and assess disease severity. 1, 2

Essential Pre-Surgical Assessment

Measure 25-hydroxyvitamin D levels immediately, as vitamin D deficiency can cause secondary hyperparathyroidism and must be excluded before confirming PHPT. 1, 2 However, given the hypercalcemia, this patient almost certainly has primary disease rather than secondary hyperparathyroidism, which typically presents with hypocalcemia or normal calcium. 3

Assess for surgical indications per Endocrine Society guidelines, which include: 1, 2

• Corrected calcium >1 mg/dL above upper limit of normal (this patient is 0.3-0.6 mg/dL above normal depending on lab reference range)
• Age <50 years
• Impaired kidney function (eGFR <60 mL/min/1.73 m²)
• Osteoporosis (T-score ≤-2.5 at any site)
• History of nephrolithiasis or nephrocalcinosis
• Hypercalciuria (>300 mg/24 hours)

Order renal ultrasonography to assess for nephrocalcinosis or kidney stones and bone density scan (DXA) to evaluate for osteoporosis, as these findings would strengthen surgical indications. 2

Surgical Referral

Refer to both an endocrinologist for medical optimization and a high-volume parathyroid surgeon for surgical evaluation, as outcomes are significantly better with specialized expertise. 2 Parathyroidectomy is the only curative treatment and should be performed in patients meeting surgical criteria. 1

Do not order parathyroid imaging (ultrasound or sestamibi scan) before confirming the biochemical diagnosis, as imaging is for surgical planning, not diagnosis. 1, 2 Once surgery is planned, preoperative localization with ultrasound and/or 99mTc-sestamibi scintigraphy with SPECT/CT should be performed. 2

Medical Management for Non-Surgical Candidates

If the patient declines surgery or is not a surgical candidate, implement the following: 1, 2

• Maintain normal calcium intake of 1000-1200 mg/day—avoid both high and low calcium diets, with total elemental calcium not exceeding 2000 mg/day 2
• Ensure adequate vitamin D levels (>20 ng/mL) with supplementation if needed, but do not supplement with vitamin D if calcium remains >10.2 mg/dL until hypercalcemia resolves 2, 3
• Monitor serum calcium every 3 months for patients with eGFR >30 mL/min/1.73 m² 2
• Ensure adequate oral hydration and discontinue any thiazide diuretics 2

Critical Pitfalls to Avoid

• Do not assume this is secondary hyperparathyroidism based on the PTH level alone—the elevated calcium definitively indicates primary disease 3
• Do not treat with active vitamin D (calcitriol, paricalcitol) when calcium is >10.2 mg/dL, as this will worsen hypercalcemia and increase risk of vascular calcification 1, 3
• Do not delay surgical referral in patients meeting criteria, as persistently elevated PTH after "cure" indicates harmful effects of severe parathyroid disease, especially in elderly patients 4
• Recognize that PTH assays vary by up to 47% between different assay generations, so always use assay-specific reference values 1, 2
• Be aware that 6% of PHPT patients have "normohormonal" presentations with elevated calcium but PTH within the reference range, and 3% have both values within normal limits—the diagnosis depends on the inappropriate relationship between PTH and calcium 5

Monitoring During Evaluation

While awaiting surgical evaluation, measure serum calcium and phosphorus at least every 3 months, and reassess renal function regularly (creatinine, eGFR) as hypercalcemia can cause acute kidney injury and worsen chronic kidney disease. 2, 3