Electrolytes (Mg++,Ca++,PO4-)

Question 1

Magnesium concentration range

Answer 1

-1.5-2.5 mg/dL

Question 2

Magnesium

Answer 2

-neuromuscular function
-cofactor (ATP and alkaline phosphatase)
-stabilize DNA/RNA
-related to Ca and K metabolism*
-regulated by intake and kidney excretion

Question 3

HYPOmagnesemia causes

Answer 3

-associated w GI or kidney probs
-diarrhea
-decreased intestinal absorption
-severe malnutrition
-Drugs (diuretics)
-Alcohol

Question 4

Drugs that can cause HYPOmagnesemia

Answer 4

-Amphotericin
-Aminoglycosides
-*Diuretics (thiazide or loop)
-cyclosporine

Question 5

HYPOmagnesemia sx

Answer 5

-hard to isolate
-usually ties with hypocalcemia and hypokalemia
-tetany, convulsions, arrhythmias
-neuromuscular: ataxia, fasiculations, seizures
-CNS: lethargy, confusion, nystagmus

Question 6

Hypomagnesemia goals of therapy

Answer 6

-tx sx
-restore Mg concentration
-correct concomitant electrolytes
-find cause
-treat other electrolyte disturbances*

Question 7

Asymptomatic Hypomagnesemia tx

Answer 7

-pts w Mg++>1mg/dL
-milk of mag 5-10mL PO QID
-Mag-Ox 800mg PO qd or 400mg TID wf

Question 8

Symptomatic Hypomagnesemia tx

Answer 8

-if Mg++ level 1-2: 0.5mEq/kg
-if Mg++<1: 1mEq/kg

-8mEq = 1 g
-infuse 1 g per hour

Question 9

Calcium normal range

Answer 9

8.5-10.5 mg/dL

Question 10

Calcium

Answer 10

-bone formation
-neuromuscular function
-controlled by parathyroid, vit D, and calcitonin
-metabolized by bone, kidneys, intestine

Question 11

Hypocalcemia causes

Answer 11

-more seen in hospitalized patients
-Mg deficiency*
-large volumes of blood products*
-Hypoalbuminemia (must correct Ca++)
-post-op hypoparathyroid
-vit D deficiency
-thyroid surgery
-meds

Question 12

Calcium correction

Answer 12

-corrected Ca = measured + ((4-measured albumin)*8))

Question 13

Ionized Ca++

Answer 13

-more accurate than calculation
-4.6-5.1 mg/dL
-represents amount of calcium available for use in body

Question 14

Hypocalcemia sx

Answer 14

-NM: parasthesias, cramps, tetany
-CNS: depression, memory loss, confusion, hallucination, seizures
-Dermatologic: hair loss, brittle nails, ecxema
-Cardiac: prolonged QT, decreased myocardial contractility, arrythmias, BRADYcardia, hypotension

Question 15

Acute tx of hypocalcemia

Answer 15

-100-300mg Ca++ IV over 5-10min
-chloride or gluconate
-rate 1gm/hr
-do NOT add to bicarb/phos solutions

Question 16

Chronic hypocalcemiatx

Answer 16

-1-3g/day Ca++
-Calcitriol 0.25mcg can increase (vit D)

Question 17

Phosphorus levels

Answer 17

2.5-4.5mg/dL

Question 18

Phosphorus

Answer 18

-cell structure/function
-resp and cardiac muscle function
-carb, fat, protein metabolism
-high energy bonds of ATP
-mods hemoglobin

Question 19

Phosphorus regulation

Answer 19

-intake
-vit D
-parathyroid hormone
-renal function

Question 20

Hypophosphatemia

Answer 20

-mild: 1-2mg/dL
-severe: <1mg/dL

Question 21

Hypophosphatemia causes

Answer 21

-dec intake
-impaired absorption
-intacellular shifts

Question 22

Hypophosphatemia presentation

Answer 22

-neuro
-muscular
-heme
-bone
-pulmonary
-cardiac
-renal

-fatigue and weakness

Question 23

mild hypophosphatemia tx

Answer 23

-oral PO4

-Phos-NaK 30-60mMol/day 2-3 divided doses
-Fleets Phospho-Soda 5mL diluted 2-3 times/day

Question 24

Severe hypophosphatemia tx

Answer 24

-IV
-potassium or sodium salts
-KPhos when K < 4 mEq/L*
-NaPhos when K>or= 4 mEq/L

Question 25

Example severe hypophophatemia tx

Answer 25

-2.3-2.9 PO4: 0.32mMol/kg
-1.6-2.2: 0.64mMol/kg
-<1.6: 1mMol/kg

Question 26

Phosphorus replacement admin

Answer 26

-PO as divided doses
-infuse IV no faster than 7mMol/h*
-remember potassium rules for infusion

Question 27

1mMol NaPhos equivalent

Answer 27

-1.33 mEq Na
-1.33mEq Phos

Question 28

1mMol KPhos equivalent

Answer 28

-1.47mEq K+
-1.47 mEq Phos