electrolyte disturbances

Question 1

effect on calcium w/ acidosis and alkalosis

Answer 1

acidosis: INCREASES calcium (just like potassium!)
alkaosis: DECREASES calcium (just like potassium)

Question 2

what to check with low calcium…

Answer 2

ALBUMIN!
low albumin causes spurious hypocalcemia - correct serum ca + (4-pt albumin)
-expect calcium to drop 0.8 per 1 g decrease in albumin

Question 3

causes of true hypocalcemia

Answer 3

1. nutrient def
2. vit d def
3. s/p parathyroidectomy
4. repeat blood transfusions (citrate binds up calcium)
5. long term bone mets
6. sepsis
7. pancreatisis
8. TSS

Question 4

approach w/ low cal <8.9

Answer 4

1. check to see if it is real
2. if real, ionized <2.26 check for signs of organ dysf: nm excitability, ecg changes (PROLONGED QT), hypotension, seizures

Question 5

hypocalcemia sx

Answer 5

1. nueromuscular excitability: + chvostek and trousseau sign, tetany, muscle weakness, convulsions, intestinal cramping
2. ECG changes: PROLONGED QT
3. resp problems: bronchospasm, resp arrest
4. cardiac sx: hypotension, arrythmias, arrest
   * *with these sx: emergent treatment!

Question 6

hypocalcemia tx

Answer 6

-indicated for symptomatic patients!
10-30 ml 10% calcium gluconate in 150 ml 5% dextrose IV over 10 min!
DONT DO MORE RAPID - CAN CAUSE BRADYCARDIA AND ASYSTOLE!
-lasts 2 hrs
-if persistent, continuous infusion 0.3-2 mg/kg/hr
-check PTH!

Question 7

type of calcium for replacement?

Answer 7

CALCIUM GLUCONATE!

-gluconate is large, won’t move in/out of cell and calcium chloride has 3 x more cal and causes necrosis!

Question 8

low PTH and low calcium, espeically in alcoholics check…

Answer 8

MAGNESIUM!!!

• low mag can cause refractory hypocalcemia and hypokalemia and hypoPTH because need mag for PTH release and action!
• ALWAYS TREAT LOW MAG!

Question 9

tx for hypomagnesemia

Answer 9

oral is preferred, unless cardiac / neuromuscular complications present, caution w/ renal dysf pt b/c excreted renally
oral: 400 mg magoxide 4-6 x day x 3-4 d
IV: 2 g magsulfate infused over 10 minutes, then continuous infusion over 6 hours (5 g in d5w)

Question 10

what to test for w/…low calcium, elevated PTH in pt w/ chronic renal failure…

Answer 10

VITAMIN D!!! (called physiologic hypocalcemia!)

-tx w/ oral calcium carbonate and calcitriol w/ low vit D!

Question 11

3 hormone, 3 organ rule…

Answer 11

hypercalcemia - think about PTH, calcitronin, vit d and bone, gut, kidney
PTH: increase serum calcium and stim active vit D
vit d:increase calcium absorption in gut, increase calcium bone mobilization and increase kidney reabsorption in distal tublule
calcitonin: lowers calcium by decreasing osteoclast activity and stimulates calciuresis

Question 12

calcium reabsorption mirrors…

Answer 12

sodium reabsorption! increased excretion w/ vol overload and decreased w/ volume contraction

Question 13

hypercalcemia sx

Answer 13

-stones, bones, moans, groans (seen w/ hyperparathyroidism too)
mental obtundation, cognitive dysf, constipation, nausea, anorexia, polyuria d/t nephrogenic diabetes insipidus, nephrolithiasis, shorted QT interval, muscle weakness

Question 14

hypercalcemia causes

Answer 14

most (>90%): malignancy and hyperparathyroidism! always check PTH first!!
-if high – primary hyperparathyroid
- if low / nl – likely malignancy
other causes: hyperthyroidism, milk-alkali, familial hypocalciuric hypercalcemia
-sarcoidosis (will have high vit d!)

Question 15

hypercalcemia - tx

Answer 15

mild (14): treat all d/t risk of CARDIAC ARREST!

- IVF 200-300 ml/hr (urine output 100-150 / hr), can add loops to increase calcium excretion
- bisphosphonates works in 2-4 days
- calcitonin - works in 12-48 hrs

Question 16

when is hypercalcemia dangerous? tx?

Answer 16

15-18 (typically symptomatic over 12)
tx of choice: fluids + loops!! (lasix)
**hemodiaysis is NOT indicated for hypercalcemia!!

Question 17

suggesting nasal polyps w/…

Answer 17

decreased sense of smell and chronic allergies! (more pain, bleeding and unilateral symptoms w/ cancer)