- Discussion:
-
physical properties
-
state in body fluids
- calcium is a necessary & important addition to cell membranes, giving strength to these structures and regulating permeability;
- physiologic roles of calcium are well established;
- abnormally low concentrations of Ca permit spontaneous discharges of both sensory & motor fibers in peripheral nerves, leading to tetany;
- see
depolarization and
calcium regulation of muscle contraction;
- w/ elevated levels, nerve impulses are blocked, leading to coma;
- normal levels:
- serum: 4.2-5.3 mEq/L or 8.5-10.5 mg/dL;
- ionized: 2.24-2.46 mEq/L or 4.48-4.92 mg/dL
-
inciting causes of hypercalcemia
-
signs & symptoms
-
EKG changes
-
calcification of soft tissue
- Initial Management:
- determine if the patient is symptomatic;
- d/c all thiazide
diuretics; (decr Ca excretion);
- d/c Vit D and Calcium Supplements;
- correct volume depletion / expand extracellular volume; (r/o CHF);
- give NS 500 ml IV "wide open" (will dilute Ca/promote excretion)
- pt may require upto 4-10 liters of NS per day, inorder to keep patient in volume expanded state;
- when hypercalcemia is mild (serum Ca level, <3.00 mmol/liter), hydration with saline is often adequate, and most pts do not require drug therapy;
- even when hypercalcemia is more severe, hydration w/ saline is first step in management;
- establish diuresis > 2500 ml/day;
-
lasix 20-40 mg IV q2-4 hr (will increase Ca excretion);
-
severe hypercalcemia:
- w/ life-threatening hyperCa (mroe than 4.00 mmol/l or more than 16 mg / dl), unequivocally symptomatic, or both, more specific therapy is required in addition to saline;
- consider dialysis;
-
calcitonin
- in this situation, most rapid-acting osteoclast inhibitor, calcitonin, becomes a first-line drug;
- it has the advantage of being relatively rapid-acting and is given in single dose;
- since calcitonin alone is unlikely to reduce serum Ca concentration to normal, however, additional therapy should be considered;
- if there are no contraindications, such as renal or hepatic dysfunction,
thrombocytopenia, or coagulopathy,
mithramycin;
- Disuse Hypercalcemia:
- immobilization can lead to significant decrease in bone formation (without affecting bone resorption);
- the result is hypercalcemia;
- these patients should be managed with either
calcitonin or
pamidronate
- Hypercalcemia Second to Malignancy: (
metastatic bone disease);
-
corticosteroids:
-
prednisone 5-15 mg po qd;
-
hydrocortisone (solu-cortef) 40-60 mg iv qd in dd;
-
indomethacin 50 mg po q8hr;
-
calcitonin
-
mithramycin:
- 15-25 ug/kg IV in 1 lit of NS over 3-6 hrs;
- onset of action in 24 hours;
- agents that are nephrotoxic should be avoided if possible;
- plicamycin (also called mithramycin) is not ideal agent for hypercalcemia in myeloma because it is directly toxic agent and it depends on the kidneys for excretion;
-
etidronate
-
pamidronate
-
clodronate
Drug Therapy -- Management Of Acute Hypercalcemia.
Hypercalcemia and bone resorption in malignancy. [Review]
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