Academic Day Seminars

ADS – Lytes reflection

This was not a lyte academic half day (har har…)

During this day Anna and Winnie (two of the adult residents) alongside with Dr. Loh taught us all about the hypos and hypers of calcium, phosphate (hypo only), magnesium, potassium!

Calcium

  • Drug causes of hypercalcemia:
    • Thiazides: dec. urinary calcium excretion
    • Lithium: inc. PTH by increasing the set point at which calcium suppresses PTH release
    • Calcium carbonate supplements: may lead to milk alkali syndrome
    • Tamoxifen: inc. bone resorption
    • Vitamin D, calcitriol, topical calcipotriol: inc. calcium absorption and bone resorption
  • Hypercalcemia treatment:
    • Normal saline: fluid resuscitation is utilized because your body is trying to excrete the Ca+2 so water goes out with it (can risk the patient becoming dehydrated and causing a vicious cycle of further hypercalcemia.
    • Salmon calcitonin
    • Pamidronate
    • Zoledronic acid
    • Glucocorticoids
    • Denosumab
    • Furosemide
    • Hemodialysis
  • Drug causes of hypocalcemia:
    • Bisphosphonates: osteoclastic bone resorption
    • Calcium chelators: dec. ionized concentration of calcium
    • Chemotherapy (cisplatin, cyclophosphamide), aminoglycosides, loop diuretics: 2 cause by inducing hypomagnesemia
    • Calcimimetics: suppresses PTH release
    • Anti-convulsants (phenytoin, phenobarb): inc. vit D catabolism to inactive compounds
  • Treatment of hypocalcemia:
    • Calcium supplementation

Phosphate

  • Role of phosphate: structural element of bones, phospholipid cell membranes (if hypo = hemolysis), nucleic acids, phosphoproteins, energy source (ATP), acid/base balance
  • Drug causes of hypophosphatemia:
    • Phosphate-binding drugs: sucralfate, calcium carbonate, Al/Mg antacids, sevelamer, lanthanum carbonate
    • Increase renal elimination of phosphate: diuretics (acetazolamide and osmotic diuretics)
  • Treatment: phosphate supplements.

Potassium

  • Hyperkalemia drug causes:
    • Intake:
      • KCl
    • Excretion:
      • Decreased aldosterone: ACEI/ARBs, K+ sparing diuretics, NSAIDs, heparin, non-selective b-blockers
      • Block Na+ channels: K+ sparing diuretics, TMP-SMX
    • Transcellular shift: digoxin, NSAIDs, non-selective beta-blockers, anesthetics (succinylcholine)
  • Hypokalemia drug causes:
    • Excretion: Thiazide diuretics, loop diuretics, mineralocorticoids, high dose glucocorticoids, ampB, high-dose penicillins, aminoglycosides, cisplatin, laxative abuse
    • Transcellular shift: insulin, beta-adrenergic agents, synthroid, caffeine/theophylline, decongestants, verapamil (high dose)

Magnesium

  • Hypomagnesemia (is often asymptomatic)
    • Drug causes:
      • Transcellular shift: high dose catecholamines, insulin
      • Excretion: loop diuretics, aminoglycosides, ampB, cisplatin, cyclosporin, antivirals, PPI, digoxin, tacrolimus, theophylline
  • Hypermagnesemia
    • Drug causes:
      • Lithium, excessive antacid/laxative use
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