Thyroid & Adrenal
Hypercalcemic crisis is seen in all except:
a. Occasionally, patients with primary HPT are initially seen after symptoms and extremely high serum calcium levels have developed.
b. Management of a so-called hypercalcemic crisis involves urgent medical and surgical strategies.
c. Pharmacologic agents associated with or adversely affected by hypercalcemia need to be discontinued; specifically, digoxin potentiates arrhythmias in the setting of hypercalcemia.
d. These patients are almost always severely dehydrated, and initial management requires hydration with normal saline.
e. Intravenous (IV) fluids, preferably normal saline, are administered at a rapid rate (200-300 mL/hr) to reverse the intravascular volume contraction and promote renal excretion of calcium.
f. Glucocorticoids lower calcium by inhibiting the effects of vitamin D.
g. They also have been shown to decrease intestinal absorption of calcium, increase renal calcium excretion, and inhibit osteoclast-activating factor.
h. Glucocorticoids are particularly effective in the setting of hypercalcemia secondary to granulomatous disease, where the hypercalcemia stems from vitamin D toxicity.
i. The initial dose of hydrocortisone is 200 to 400 mg/day IV for 3 to 5 days. Steroids are ineffective in most cases of hypercalcemia associated with malignancy.
j. Hypercalcemia of malignancy occurs by two mechanisms:
i. as a direct result of extensive osseous metastases and
ii. indirectly by release of parathyroid hormone–related peptide (PTHrP) by the tumor.
k. Gallium nitrate, a compound that inhibits osteoclast resorption and lowers calcium levels, can be used at 200 mg/m2 daily IV for 5 days.
l. Calcitonin acts quickly (within 24-48 hours) to lower serum calcium levels and is more effective when used in combination with glucocorticoids.
m. Bisphosphonates are pyrophosphate analogues that have high affinity for hydroxyapatite in bone. They potently inhibit osteoclast activity for up to a month.
n. In hypercalcemia of malignancy, pamidronate (90 mg IV) or zoledronic acid (4 mg IV as initial treatment, 8 mg on re-treatment) normalizes calcium levels in most patients.