- Diff Dx:
-
Renal Failure
- Secondary Hyperparathyroidism
-
Hypoparathyroidism (surgical, psuedo)
- Immobilization
- Addison's dz
- Bone dz (Healing frx)
- Factitious increase (hemolysis of specimen)
- Vit D toxicity
-
Tumoral Calcinosis
- Discussion:
- Adult nl value: 2.3-4.7 mg/dL; Child 4.0-7.0 mg/dL;
- w/ concomitant
hypercalcemia:
- if serum phosphate concentration is markedly elevated in severe
hypocalcemia, correction of
hyperphosphatemia must be carried out with IV
glucose and
insulin before calcium is given
inorder to avoid metastatic calcification;
- renal failure with
hypocalcemia and hyperphosphatemia:
- Management:
- when serum phospate concentration > 6 mg/dl, Mg free phospate binding antacids should be prescribed
with meals to minimized elevations in calcium phospate product and attenuate soft tissue depositon of
calcium-phospate crystals;
- ionized Calcium in acute renal failure is usually near normal, owing to acidosis, uremic state, and hypoalbuminemia;
- infusion of calcium is therefore unnecessary unless carpopedal spasm or tetany develops;
- in other pts, the major clinical findings in hyperphosphatemia include
hypocalcemia and
ectopic calcification, both due to formation of calcium phosphate complexes;
- pts w/ diabetic
ketoacidosis commonly have hyperphophatemia at time of presentation despite total body Pi depletion;
- insulin, fluid, and acid base therapy is accompanied by shift of Pi back into cells and development of hypophosphatemia;
- Tumor Lysis
- massive tumor lysis results from release of intracellular phosphate during massive cell destruction;
- commonly occurs during chemo for ALL in children;
- serum Pi levels typically rise w/in 1-2 days after initiating treatment;
- rising serum Pi concentration often is accompanied by
hypocalcemia, hyperuricemia,
hyperkalemia, and renal failure;
