Confusion and hypercalcemia in an 80-year-old man

Cleveland Clinic Journal of Medicine. 2017 April;84(4):281-286 | 10.3949/ccjm.84a.16017
April 3, 2017|Cleveland Clinic Journal of Medicine
Keren Zhou, MD;Steven Assalita, MD;Susan E. Williams, MS, RD, MD, FACP FACE
Author and Disclosure Information

Keren Zhou, MD
Department of Internal Medicine, Cleveland Clinic

Steven Assalita, MD
Department of Cardiology, Baylor College of Medicine, Houston, TX

Susan E. Williams, MS, RD, MD, FACP FACE
Department of Endocrinology, Diabetes, and Metabolism, Cleveland Clinic; Associate Professor, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH

Address: Keren Zhou, MD, Department of Internal Medicine, NA10, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195; zhouk2@ccf.org

LONG-TERM TREATMENT

4. In the continued management of a patient with vitamin D toxicity with severe hypercalcemia, which of the following provides prolonged benefit?

  • Intravenous hydrocortisone
  • Fluid repletion
  • Pamidronate
  • Calcium-restricted diet

Much has been postulated concerning the mechanism of vitamin D intoxication and subsequent hypercalcemia. Studies have shown it is not an increase in dietary calcium absorption that drives the hypercalcemia but rather an increase in bone resorption. As such, bisphosphonates such as pamidronate have been shown to have a dramatic and rapid effect on severe hypercalcemia from vitamin D toxicity. The duration of action varies but is typically between 1 and 2 weeks.22,30

Corticosteroids such as hydrocortisone are also indicated in situations of severe toxicity. They block the action of 1-alpha-hydroxylase, which converts inactive 25-hydroxyvitamin D to the active 1,25-dihydroxyvitamin D. Corticosteroids have also been shown to more directly reduce calcium resorption from bone and intestine in addition to increasing calciuresis.31 A small study in the United Kingdom noted that while bisphosphonates and steroids were equally effective in reducing serum calcium levels, bisphosphonates accomplished this reduction more rapidly, with a time to therapeutic effect of 9 days as opposed to 22 days.­

,

Fluid hydration, though necessary, is unlikely to produce complete correction on its own, as previously discussed.

THE PATIENT RECOVERS

The patient was treated with intravenous fluids over 3 days and received 1 dose of pamidronate. Calcitonin was provided over the first 48 hours after presentation to more rapidly reduce his calcium levels. He was advised to avoid taking the supplements prescribed by his naturopathic practitioner.

On follow-up with an endocrinologist 1 week later, his symptoms had entirely resolved, and his calcium level was 10.5 mg/dL.

TAKE-AWAY POINTS

  • A good medication history includes over-the-counter products such as vitamin D supplements, as more and more people are taking them.
  • The level of 25-hydroxyvitamin D should be monitored within 3 to 4 months after initiating treatment for vitamin D deficiency.11
  • Vitamin D toxicity can have profound consequences, which are usually seen when levels of 25-hydroxyvitamin D rise above 250 ng/mL.13
  • The Institute of Medicine recommends that the dosage of vitamin D supplements be no more than 4,000 IU/day and that doses may need to be lowered to account for concurrent use of hypercalcemia-inducing drugs and other vitamin D-containing supplements.32