Day #21 - Hypercalcemia

Today we presented a case of altered mental status related to hypercalcemia. The discussant talked about the common causes of hypercalcemia as well as touched upon management. Some relevant take home messages include:

Symptoms of Hypercalcemia: Think "STONES, MOANS, GROANS, BONES, mental OVERTONES."

Causes of Hypercalcemia:

1. Hyperparathyroidism (primary, secondary, tertiary)
2. Malignancy Associated due to:
   (a) PTHrP -- Squamous cancers of lung/throat, Breast, RCC, GU, other
   (b) Bone destruction/Local Osteoclast Activation -- Breast, Myeloma
   (c) Hypervitaminosis D -- Lymphoma, Breast (rare)
   
3. Hypervitaminosis D due to sarcoid, iatrogenic
4. Iatrogenic: Calcium supplements, thiazide diuretics, lithium, etc.
   
5. Prolonged immobility
6. Other endocrine: Hyperthyroidism, Acromegaly, Adrenal Insufficiency
7. Other

NB: The malignancy is usually clinically apparent!

Treatment:

• If possible, remove the precipitant and correct any hypophosphatemia.
  
• Saline replacement of ECF volume then maintenance of euvolemia. Often requires several litres of IV fluid to correct for the profound ECF contraction. Hydration alone will often bring the calcium down significantly
  Consider the addition of FUROSEMIDE if you've made them hypervolemic.
  
• IV Bisphosphonates: Pamidronate 45-90mg IV over 90 minutes. Will work within 48-72 hours. Watch for post treatment hypocalcemia
• If still unsuccessful:
  (a) ensure you are not behind in hydration!!!
  (b) can add calcitonin 4-8IU/kg SC q12h
  (c) consider adding PREDNISONE 60mg PO OD x 10d if suspect the problem is increased 1,25-OH vitamin D
  (d) Consider dialysis

I have only had to resort to measures beyond bisphosphonates once and in that case (lymphoma associated) there was a great (initial) response to prednisone.

A great review article on hypercalcemia and malignancy is here.