McCarthy: K+, Ca+, Mg Flashcards
Albumin is __ grams in reference to calculating the corrected calcium
4g
normal lab value: total Ca+, ionized Ca+
total: 8.5 – 10.5 mg/dl
ionized: 4.6-5.1 mg/dl
normal lab value: phosphorous
2.5-4.5 mg/dl.
what kind of Ca is biologically active?
only free (ionized) is biologically active
effect on/from Ca and/or K balance? D50
aka glucose(dextrose + H2O)
- used to txt hyperKalemia, can cause hypoKalemia
- increase blood sugar (given with insulin)- if hyperkalemia is bad enough, very acidodic
- give w/out insulin, the body would produce insulin and drive K+ into cells
effect on/from Ca and/or K balance? insulin
txt hyperKalemia
- helps drive K+ into cells
effect on/from Ca and/or K balance? Kayexelate
- used to txt hyperKalemia
-binds K+ in GI and excretes it in feces
Removal of K+ takes time, so short term tx strategies involve temporary shifts of K+ from extracellular to intracellular compartment
(kayexalate = cation exchange resin)
effect on/from Ca and/or K balance? albuterol
- used to txt hyperKalemia
-drives K+ into the cells
(via increasing activity of Na/K-ATPase pump)
( B2 agonist )
effect on/from Ca and/or K balance? calcitonin
txt hyperCalcemia by inhibiting bone resorption
osteoclast inhibitor
effect on/from Ca and/or K balance? bicarbonate
txts hyperKalemia
(when caused by acidosis)
-Acidosis: H+ in ECF, it enters cell to buffer, K+ leaves cell to balance. there is then DECREASED driving force for K+ secretion = hyperkalemia
*can cause slight alkalosis
effect on/from Ca and/or K balance? CCBs
if you see on test, this is a WRONG answer
effect on/from Ca and/or K balance? ARBs
txt hypoKalemia
-raises blood potassium
effect on/from Ca and/or K balance? ACE-Is (lisinopril)
txt hypoKalemia
-raises blood potassium
effect on/from Ca and/or K balance? prednisone
increases urinary losses of potassium (hypokalemia)
-manifests in people with too much cortisol (cushing’s- causes hypokalemia)
effect on/from Ca and/or K balance? Digoxin
worry about increased digoxin toxicity with hypoKalemia (when on diuretic and digoxin- can get hypoKalemia and a fatal arrhythmia)
-WONT drive K in or out of cell specifically. it inhibits the Na/K atpase pump- inhibiting K from going into the extracellular space
(not used much anymore)
effect on/from Ca and/or K balance? TZD (hydrochlorothiazide)
can CAUSE hypokalemia
-acts on the early distal tubule cells (upstream of principle cells) = increase Na+ delivery to principle cells= more Na+ reabs. here and more K+ secreted.
effect on/from Ca and/or K balance? K+-sparing diuretics
spironolactone/triamterene
- can CAUSE hyperkalemia
- Acts on early distal tubule cells and collecting duct principal cells.
- Should be avoided in renal dysfunction patients.
effect on/from Ca and/or K balance? loop diuretics (lasix/furosemide)
- can CAUSE hypokalemia
- Acts on thick ascending loop of Henle
effect on/from Ca and/or K balance? loop diuretics (lasix/furosemide)
- can CAUSE hypokalemia
- Acts on thick ascending loop of Henle
normal lab values: Mg
1.8 – 2.7 mg/dl
overall: increased Na+ delivery to principle cells causes what effect on K+?
increased K+ excretion
*With the exception of metolozone, thiazide diuretics are not effective in what pts?
pt w/ renal insufficiency (GFR < 30)
what disorders can cause increased PTH?
- primary hyperparathyroidism
- pseudohypo-parathyroidism
- chronic renal failure
- vit D deficiency
what disorders can cause decreased PTH?
- surgical hypo-parathyroidism
- humoral hypercalcemia of malignancy
what disorders can cause increased serum Ca+ ?
- primary hyperparathyroidism
- humoral hypercalcemia or malignancy
what disorders can cause increased serum Ca+, and decreased serum phosphate ?
- primary hyperparathyroidism
- humoral hypercalcemia or malignancy
what disorders can cause decreased serum Ca+, and increased serum phosphate?
- surgical hypo-parathyroidism
- pseudohypo-parathyroidism
- chronic renal failure
how can you tell the difference between chronic renal failure and vit D deficiency?
BOTH: increased PTH, low Ca+
chronic renal failure: high phosphate
vit D def.: low phosphate
what disorders have increased urine cAMP?
- primary hyperparathyroidism
- humoral hypercalcemia or malignancy
(same as those with increased Ca+ and decreased phosphate)
what disorders have decreased urine cAMP?
- surgical hypo-parathyroidism
- pseudohypo-parathyroidism
(same as those with decreased Ca+ and increased phosphate - except renal failure)
what is primary hyperparathyroidism?
is a disorder of one or more of the parathyroid glands
- The parathyroid gland(s) becomes overactive and secretes excess amounts of parathyroid hormone (PTH).
= blood Ca+ rises to a level that is higher than normal (called hypercalcemia).
what is surgical hypoparathyroidism? symptoms?
symptoms post-neck surgery: check symtpoms of hypoparathyroidism (may be sign of destruction of parathyroid)
-neural irritability : tingling, numbness, parasthesias (b/c easier to depolarize).
hyperventilation (maybe weeds)
-how does it effect Ca+ and PTH
blowing off CO2 = alkalotic … leads to tingling, numbness, parasthesias (from decr. ionized Ca+)
when pH normal- there is competition between neg. charges, H+ and Ca+. but if you dec. H+ ion conc, theres a greater chance for Ca+ to bind vacant albumin- then you DO have decr. ionized Ca+ (serum)
—> but PTH should respond and correct this.
txt for decreased ionized Ca+ from hyperventilation (if PTH doesn’t respond and correct it) ?
TXT with Calcium and active form of vit D (1,25 dihydroxycholecalciferol)
what is pseudohypoparathyroidism?
parathyroid is normal
looks like surgical hypoparathyroid except PTH also high
receptors on the bones and kidney in target tissue.
-you have normal/high PTH but its not working on the receptors of target tissue
what is humoral hypercalcemia of malignancy?
humoral hypercalcemia of malignancy- most common kind of hypercalcemia- lung cancer (squamous cell carcinoma)
tumor acts just like PTH - activates receptors in bone and kidney - hyperCa and decr. phos
increased urine cAMP
chronic renal failure
decrease GFR = incr. serum phosphorous ( and inverse relationship with calcium so you get hypocalcemia)
-naturally stimulate PTH
txt for primary hyperparathyroidism
txt with surgery (remove parathyroid glands)
medical txt: txt underlying disease. hyperCa+ makes them volumed depleted so txt with saline to restore volume, txt with lasix (block Na+ reabs so you dont get Ca+ reabs. = calcium diuersis to lower Ca+)- once they are hydrated, then give IV bisphosphonates.
goal to prevent initial hyperphosphatemia- give calcium carbonate (binder) - so complex is not absorbed.
txt for surgical hypoparathyroidism
calcium and activated form vitamin D (1,25)
txt for humoral hypercalcemia of malignancy
hyperCa+ makes them volumed depleted so…
- txt with saline to restore volume
- txt with lasix (block Na+ reabs so you dont get Ca+ reabs. = calcium diuersis to lower Ca+)
- once hydrated, txt w/ IV bisphosphonates.
txt chronic renal failure
goal: prevent initial hyperphosphatemia
- give calcium carbonate (binder) - so complex is not absorbed.
Urinary potassium excretion, is primarily determined by secretion where?
in the principal cells in the cortical collecting tubule
how does aldosterone effect K+ excretion?
increases K + excretion
metabolic acidosis (and hyperosmolarity) cause of K+ shifts into or out of cells?
shifts K OUT of cell, causing hyperkalemia
alkalosis and (hypo-osmolarity) both cause K+ to go into or out of the cell?
shifts K+ INTO cell , causing hypokalemia
insulin deficiency causes what change to K+?
hyperkalemia (b/c can’t be driven into cells)
decrease in GFR causes what change in K+? how does this happen? what are two causes of this?
hyperkalemia
- b/c diminished Na+ and H2O delivery to distal tubule (principal cells)
(decrease GFR causes- renal failure or severe CHF - w/ volume depletions)
low aldosterone (hypoaldosteronism) has what effect on K+? what drugs may cause this?
hyperkalemia
(NSAIDs, ACEs, spironolactone, etc.)
- also primary adrenal insufficiency
