What is the diagnosis and management for a patient with hypercalcemia and elevated parathyroid hormone (PTH) level?

Primary Hyperparathyroidism: Diagnosis and Management

Your patient has primary hyperparathyroidism (PHPT) based on the combination of hypercalcemia (10.6 mg/dL) with an inappropriately normal/elevated PTH (96 pg/mL), and this requires surgical evaluation as the only definitive cure. 1, 2

Diagnostic Confirmation

Biochemical diagnosis is definitive: The presence of elevated calcium with a PTH that is not suppressed (normal or elevated) confirms PHPT, regardless of imaging results. 2, 3 In your case:

• Calcium 10.6 mg/dL exceeds the hypercalcemia threshold of >10.2 mg/dL 2
• PTH 96 pg/mL is inappropriately normal-to-elevated in the setting of hypercalcemia 2
• This biochemical pattern is diagnostic of PHPT even when PTH falls within the laboratory reference range 4, 5

Critical point: Patients with hypercalcemia and PTH levels ≤50 pg/mL still have PHPT with 96.7% surgical cure rates, so your patient with PTH of 96 pg/mL clearly meets diagnostic criteria. 5

Essential Additional Workup Before Surgery

Measure these laboratory values immediately:

• 25-hydroxyvitamin D level to exclude vitamin D deficiency as a concomitant secondary cause of elevated PTH 1, 2
• Serum creatinine and eGFR to assess kidney function, as impaired function (eGFR <60 mL/min/1.73m²) is itself a surgical indication 2
• 24-hour urine calcium or spot urine calcium/creatinine ratio to evaluate for hypercalciuria (>300 mg/24hr is a surgical indication) 1, 2
• Serum phosphorus (typically low-normal in PHPT) 2
• Bone density scan (DEXA) if chronic hyperparathyroidism is suspected, as osteoporosis (T-score ≤-2.5) is a surgical indication 2

Imaging for surgical planning only (not diagnosis):

• Ultrasound and/or dual-phase 99mTc-sestamibi scintigraphy with SPECT/CT for parathyroid adenoma localization 1, 3
• Do not order imaging before confirming biochemical diagnosis 2
• Negative imaging does not exclude PHPT—the biochemical diagnosis is definitive 3

Surgical Indications

Refer to endocrinology and an experienced parathyroid surgeon if ANY of the following criteria are met: 1, 2

• Corrected calcium >1 mg/dL above upper limit of normal (>11.3 mg/dL)
• Age <50 years
• Impaired kidney function (eGFR <60 mL/min/1.73m²)
• Osteoporosis (T-score ≤-2.5 at any site)
• History of nephrolithiasis or nephrocalcinosis
• Hypercalciuria (>300 mg/24hr)

Your patient with calcium 10.6 mg/dL likely meets criteria depending on age, kidney function, and bone density results. 2

Surgical Approach

Parathyroidectomy is the only definitive cure for PHPT: 1

• Minimally invasive parathyroidectomy (MIP) is preferred when preoperative imaging successfully localizes a single adenoma, offering shorter operating times and faster recovery 1
• Bilateral neck exploration (BNE) is indicated when imaging is negative or suggests multiglandular disease 3
• Experienced parathyroid surgeons achieve >95% cure rates even with negative imaging 3
• Note: Patients with PTH ≤50 pg/mL have higher rates of multiglandular disease (58.9%), so bilateral exploration should be strongly considered 5

Medical Management (If Surgery Declined or Contraindicated)

For patients who cannot undergo or decline parathyroidectomy: 2

• Maintain normal calcium intake (1000-1200 mg/day)—avoid both high and low calcium diets 2
• Ensure 25-hydroxyvitamin D levels >20 ng/mL (50 nmol/L) with supplementation if needed 6, 1
• Monitor serum calcium every 3 months 2
• Cinacalcet may be considered for medical management in patients unable to undergo surgery 7
  • FDA-approved for primary HPT when parathyroidectomy is indicated but patient cannot undergo surgery 7
  • Starting dose: 30 mg twice daily, titrated every 2 weeks to maximum 90 mg four times daily 7
  • In clinical trials, 75.8% of patients achieved calcium ≤10.3 mg/dL 7

Post-Surgical Management

Immediate postoperative monitoring is critical: 6, 1

• Measure ionized calcium every 4-6 hours for first 48-72 hours, then twice daily until stable 6, 1
• Have IV calcium gluconate immediately available (1-2 mg elemental calcium/kg/hour) if ionized calcium falls below 0.9 mmol/L (3.6 mg/dL) 6
• When oral intake possible, provide calcium carbonate 1-2 g three times daily plus calcitriol up to 2 mcg/day 6
• Discontinue or reduce phosphate binders as dictated by serum phosphorus levels 6

Common Pitfalls to Avoid

Do not dismiss PHPT based on "normal" PTH: A PTH within the laboratory reference range is inappropriately elevated in the setting of hypercalcemia and confirms PHPT. 4, 5, 8

Do not delay surgery in symptomatic patients: Even mild hypercalcemia can cause fatigue, constipation, and cognitive symptoms in approximately 20% of patients. 9

Do not order parathyroid imaging before biochemical confirmation: Imaging is for surgical planning only, not diagnosis. 2, 3

Do not supplement with vitamin D until hypercalcemia is resolved: Vitamin D supplementation can worsen hypercalcemia by increasing intestinal calcium absorption. 2

Do not use sodium citrate for stone prevention: Use potassium citrate instead to avoid increasing urinary calcium excretion. 1