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I have several patients, both male and female, with persistent hyperparathyroidism ranging from 3 to 6 years after cadaveric renal transplantation with stable creatinine at 0.9 mg/dL to 1.2 mg/dL. They have hypercalcemia with serum calcium ranging from 10.5 to 11.5, serum phosphorus ranging from 3 mg/dL to 4 mg/dL, and iPTH (intact PTH) ranging from 150 to 300 pg/mL and stable. Sestamibi scan and neck ultrasound do not show enlarged glands. Should I stop worrying about the hypercalcemia?
David Law, MD
Slightly elevated serum calcium related to persistent hyperparathyroidism is present in up to 25% of patients following kidney transplantation, although this generally reverts to normal within 6-8 months. Hyperparathyroidism in this setting is usually the result of autonomous production from enlarged glands. Calcium and vitamin D receptors may be downregulated with resistance to serum calcium and vitamin D, and corticosteroids may upregulate the production of pre-parathyroid hormone (PTH), further stimulating the parathyroid gland. If patients have elevated levels of calcium but are otherwise asymptomatic, PTH levels should be closely monitored while other causes of elevated calcium are investigated. Such causes may include excessive calcium and vitamin D ingestion, aluminum toxicity, and the development of malignancies posttransplantation. Progressive hyperparathyroidism is evidenced by worsening skeletal parameters, kidney stones, and muscle weakness. Hypercalcemia may be associated with the development of erythrocytosis. In the setting of the asymptomatic patient, optimal conservative management is suggested, with parathyroidectomy and autotransplantation reserved for patients with enlarged glands.
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