Fluids and Electrolytes Part 2

What is the normal range of Potassium?

3.5-5 mEq/L

What is the primary organ involved in maintaining potassium levels?
-it is mediated by...

Kidneys
-aldosterone

Role of Potassium
Determination of electrical action potential...

-Neuromuscular activity
-Cardiac conduction

Which meds can cause Hypokalemia (<3.5)?

Beta-2 agonists
Verapamil toxicity
Insulin
Diuretics
Mineralocorticoids
High-dose glucocorticoids

What are additional causes of Hypokalemia (<3.5)?

Concomitant hypomagnesemia
Renal losses
Diarrhea

Clinical presentation of Hypokalemia
Asymptomatic
Muscle cramping, weakness, malaise, myalgias
Arrhythmias, St-depression, impaired muscle contractility

Mild
Moderate
Severe

Hypokalemia - goal of therapy is to return serum K levels to...

>/= 4

Hypokalemia Treatment Rule of thumb:
Each 10 mEq of K+ should raise serum K+ by...
-What should be corrected 1st if it is also present?

0.1 mEq/L
hypomagnesemia

Which ROA is recommended if symptomatic or severe (<2.5 mEq/L)?
-when can you go up to 20 mEq/h?

IV - max rate of 10mEq/h
If central line AND patient has continuous cardiac monitoring

Hypokalemia alternatives for chronic supplementation:

Potassium-sparing diuretics
-Spironolactone
-Triamterene
-Amiloride

Symptoms of Hyperkalemia:
Signs of Hyperkalemia:

Typically asymptomatic
Muscle twitching
Heart palpitation
EKG changes: Peaked T waves

Which medication should be used for Hyperkalemia for cardiac muscle stabilization only if there are EKG changes?

Calcium gluconate (or chloride)

1st line treatment of Hyperkalemia if no EKG changes:
-most rapid correction

Insulin + dextrose
Albuterol
Sodium bicarbonate

Hyperkalemia
2nd line treatment for symptomatic, 1st line for mild, asymptomatic
What's last line?

Furosemide
Sodium polystyrene sulfonate
Sodium zirconium cyclosilicate
Hemodialysis

Hyperkalemia
Sodium polystyrene sulfonate (Kaexylate) and Sodium zirconium cyclosilicate (Lokelma) is not for which patients?
Why?

severe or symptomatic patients
onset of action is 1hr

Hyperkalemia
For acute, symptomatic patients, how must we monitor?

Serum K+ hourly until <5 mEq/L

What is the normal range of Magnesium?

1.8-2.4 mg/dL

Which organ is largely responsible for homeostasis and elimination of magnesium?

Kidneys

Majority of magnesium stores located in...

bone (67%) and muscle (20%)

Hypomagnesemia is commonly associated w...
-Treat hypomagnesemia 1st!

hypokalemia and hypocalcemia

Hypomagnesemia goal of therapy:

serum Mg >/= 2 mg/dL

Hypomagnesemia Treatment
Which ROA is preferred in acute setting?
Up to ___ of magnesium dose will be ___ excreted
-Dose is reduced by 50% in patients with....
Magnesium can take how long to re-equilibrate stores in the body?

IV
50% ; renally
renal impairment
2-3 days

What is the normal range of Calcium?

8.5-10.5 mg/dL

Calcium is regulated by...

Vitamin D and PTH

Hypocalcemia
Oral supplementation is safe for...
Initial doses =
-Often co-administered w Vitamin D

mild, asymptomatic hypocalcemia or chronic supplementation
1-2g elemental calcium/day

Hypocalcemia
IV supplementation:
Symptomatic:
Asymptomatic, mod-severe:

1g calcium chloride or 3g calcium gluconate
2-4g calcium gluconate

Between calcium chloride and calcium gluconate, which has a greater elemental calcium content?
and which is less irritating to veins and less risk of extravasation?
Calcium chloride should be administered via

Calcium chloride
Calcium gluconate
central vein

Hypercalcemia Goals of therapy:

Prevent arrhythmias
Return to normal serum levels

1st line treatment of Hypercalcemia:
(symptomatic managment)

IV isotonic fluids - immediate onset (NS bolus)
+
Loop diuretics - immediate onset (Furosemide)

2nd line treatment of Hypercalcemia:
(asymptomatic management)

Calcitonin (Miacalcin) - IM/SQ

ADEs of Calcitonin (Miacalcin):

Allergic reaction (test dose required)
Tachyphylaxis (resistance) with chronic therapy

What is used in hypercalcemia of malignancy?
-What is their onset of action

Bisphosphonates
2-7 days

Phosphorus normal range:
-Primarily located in

2.5-4.5 mg/dL
bone

Phosphorus homeostasis is closely tied to ___ homeostasis

calcium

Which cause and symptom is unique to Hypophosphatemia?

Respiratory dysfunction

Hypophosphatemia Goals of therapy:
Serum phosphorus level of...

>/= 3mg/dL

Which is the preferred ROA for Hypophosphatemia?

Oral supplementation

Oral and IV preps of Phosphate should be reduced by 50% in patients with...
Usual dose of oral prep:
Max infusion of IV prep:

renal dysfunction
50-60 mmol/day in divided doses
7 mmol phosphate/hr