Primary hyperparathyroidism: Labs to order, Tx to consider
Unexplained kidney stones, osteoporosis, or certain subtle clues may point to hyperparathyroidism. These tests and imaging options can help you to be sure.
PRACTICE RECOMMENDATIONS
› Evaluate suspected cases of primary hyperparathyroidism (PHPT) with serum total calcium, parathyroid hormone (PTH), creatinine, and 25-hydroxy vitamin D levels. A
› Consider 24-hour urine measurement of calcium and creatinine in patients undergoing evaluation for possible PHPT. A
› Obtain bone densitometry at the spine, hip, and distal radius in patients with PHPT. A
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
Perform imaging before surgery to identify the overactive parathyroid glands. Ultrasound can detect enlargement of the parathyroid glands. A sestamibi scan, which measures the uptake of Tc99-sestamibi by the parathyroid glands, reflects the activity of the parathyroid glands. In cases of nonlocalization by these 2 modalities, other imaging techniques like 4D CT scan and contrast-enhanced ultrasound can be used. Of note: Imaging is used for localization, but not for diagnosis.
Intra-operative PTH measurement has added to the efficacy of minimally invasive parathyroidectomy. A drop in PTH of >50% after 10 to 15 minutes of excising the gland is considered to be positive.10
Medication management
Monitor patients who refuse surgery or those who do not meet the criteria after surgery. Serum Ca2+ and PTH are monitored annually. DEXA scan needs to be repeated every 1 to 2 years based on the clinical picture. Also assess patients for any fragility fractures and renal endpoints. Recommend taking vitamin D to keep the level above 20 ng/dL.10 Ca2+ intake should follow normally recommended guidelines.
Bisphosphonates are primarily used for the treatment of osteoporosis accompanying PHPT. They decrease bone resorption and, to a lesser extent, bone formation. Alendronate increases BMD at the lumbar spine, but does not have much effect on Ca2+ and PTH levels.
Calcimimetics act by mimicking the effects of Ca2+ on the Ca2+ receptors present on the surface of the parathyroid cells. Therefore, calcimimetics reduce the level of parathyroid hormone and Ca2+ levels. (Long-term benefits have not been established.) Bisphosphonates are prescribed for osteoporosis and calcimimetics for hypercalcemia.10
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