What is the workup for hyperparathyroidism (Primary Hyperparathyroidism)?

From the Guidelines

The workup for primary hyperparathyroidism (PHPT) should begin with biochemical testing, specifically serum calcium and serum PTH, to confirm the diagnosis, followed by imaging studies to localize the abnormal parathyroid gland(s), as recommended by the most recent guidelines 1. The initial laboratory evaluation should include serum calcium, intact parathyroid hormone (PTH), 25-hydroxyvitamin D, phosphorus, and renal function tests.

• Key laboratory tests:
  • Serum calcium
  • Intact parathyroid hormone (PTH)
  • 25-hydroxyvitamin D
  • Phosphorus
  • Renal function tests When elevated calcium and PTH levels are confirmed on multiple occasions, imaging studies should be ordered to localize the abnormal parathyroid gland(s).
• First-line imaging options:
  • Sestamibi scan
  • Neck ultrasound These imaging modalities are used to guide targeted curative surgery, such as minimally invasive parathyroidectomy (MIP), which is a recommended operative strategy for PHPT 1. Additional testing should include 24-hour urine calcium to assess for hypercalciuria and bone mineral density testing to evaluate for osteoporosis.
• Additional tests:
  • 24-hour urine calcium
  • Bone mineral density testing Renal imaging (ultrasound or CT) is recommended if there is a history of kidney stones.
• Renal imaging:
  • Ultrasound
  • CT scan Laboratory evaluation should also include albumin (to calculate corrected calcium), creatinine, and alkaline phosphatase.
• Additional laboratory tests:
  • Albumin
  • Creatinine
  • Alkaline phosphatase Family history should be obtained to screen for genetic syndromes like Multiple Endocrine Neoplasia.
• Family history:
  • Screen for genetic syndromes like Multiple Endocrine Neoplasia The diagnosis is confirmed when hypercalcemia exists with inappropriately normal or elevated PTH levels in the absence of other causes, as stated in the guidelines 1. Imaging has no utility in confirming or excluding the diagnosis of PHPT, but it plays a crucial role in localizing the abnormally functioning gland or glands with high accuracy and high confidence to facilitate targeted curative surgery 1.

From the FDA Drug Label

1 INDICATIONS AND USAGE

1.3 Primary Hyperparathyroidism Cinacalcet tablets are indicated for the treatment of hypercalcemia in adult patients with primary HPT for whom parathyroidectomy would be indicated on the basis of serum calcium levels, but who are unable to undergo parathyroidectomy [see Clinical Studies (14.3)].

The workup for Primary Hyperparathyroidism is not directly addressed in the FDA drug label.

• The label discusses the treatment of hypercalcemia in patients with primary HPT, but does not provide information on the diagnostic workup.
• It mentions that cinacalcet is indicated for patients with primary HPT who have serum calcium levels that would indicate parathyroidectomy, but are unable to undergo surgery 2.
• However, the label does not provide specific guidance on the diagnostic evaluation or workup for primary HPT.

From the Research

Workup for Hyperparathyroidism (Primary Hyperparathyroidism)

The workup for primary hyperparathyroidism involves several steps, including:

• Biochemical evaluation to confirm hypercalcemia and elevated parathyroid hormone (PTH) levels 3, 4, 5
• Measurement of PTH(1-84), phosphate, chloride, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and calcium-to-creatinine clearance to rule out other causes of hypercalcemia 4
• Imaging studies, such as ultrasonography, nuclear medicine imaging, and computed tomography, to localize the parathyroid gland or adenoma 4, 6
• Evaluation of renal function, bone density, and presence of nephrolithiasis or nephrocalcinosis to assess the severity of the disease 3, 5

Indications for Parathyroidectomy

Indications for parathyroidectomy in primary hyperparathyroidism include:

• Presence of symptoms, such as nephrolithiasis, nephrocalcinosis, or osteoporosis 3, 5
• Age 50 years or younger 3, 5
• Serum calcium level more than 1 mg per dL above the upper limit of normal 3
• Osteoporosis or low bone mass 3, 5
• Creatinine clearance less than 60 mL per minute per 1.73 m2 3
• Nephrolithiasis or nephrocalcinosis 3, 5
• Hypercalciuria 3

Medical Management

Medical management of primary hyperparathyroidism may include:

• Optimization of calcium and vitamin D intake 5
• Antiresorptive therapy to reduce bone resorption and prevent fractures 5
• Cinacalcet, a calcimimetic agent, to lower serum calcium and PTH levels 5, 7