Approach To The Patient With Disorders Of Potassium And Magnesium

Front 1

What are causes of spurious hyperkalemia?

Back 1

Hemolysis (most common cause...ischemia, etc.)
Thrombocytosis>1,000,000
Leukocytosis>200,000
Abnormal erythrocytes
Ischemic blood drawing

Front 2

How can you tell if hyperkalemia is spurious?

Back 2

A normal EKG with a hyperkalemic blood reading

Front 3

What is the mechanism of acidosis and hyperkalemia?

Back 3

1. Decreased gradient for Na/H exchange
2. Decreased Na moving into cells..not as much Na/K exchange
3. Decreased movement of K into cells
4. HYPERKALEMIA

Front 4

What is the mechanism for hyperkalemia and acidosis?

Back 4

1. Inhibition of the Na/K atpase-->increase of Na in cells
2. Decreased influx of Na via Na/H exchange-->less H efflux
3. Increased intracellular H+, decreased ammonia production-->acidosis

Front 5

What are some causes of hyperkalemia due to redistribution?

Back 5

Exercise
Diabetes --> lack of insulin
Hyperosmolar states (hyperglycemia, mannitol)
Acidosis
Cytolysis
Catabloic states
Drugs

Front 6

What types of drugs can induce hyperkalemia?

Back 6

Beta blockers
Digitalis
Potassium sparing diuretics

Front 7

In what conditions can cause hyperkalemia due to excess consumption?

Back 7

When people aren't able to excrete it by some other cause

Front 8

What are some causes of true hyperkalemia?

Back 8

Damage to the collecting tubules
Drug-induced inhibition of principal cell transport mechanisms
Lack of functional nephrons for any reason
Reduced solute delivery to collecting tubule sites
Impaired aldosterone

Front 9

What are some of the ways that collecting tubules can be damaged in hyperkalemia?

Back 9

Obstruction

Interstitial nephritis

Front 10

What are some Na channel blockers (in principal cells) that can cause hyperkalemia?

Back 10

Amiloride
Triamterene
Pentamidine
Trimethoprim

Front 11

How is it that NSAIDs cause problems with K excretion?

Back 11

Prostaglandins produced by the kidney are regulators of blood flow. You alter the prostaglandins-->slowing of flow-->hyperkalemia

Front 12

What are some of the drugs that effect aldosterone, possibly causing hyperkalemia?

Back 12

ACEIs
A2 receptor blockers
Heparin (via hypoaldosteronism)
Spironolactone

Front 13

What are some of the manifestations of hyperkalemia?

Back 13

Cardiac arrhythmias
Decreased renal ammonia production-->metabolic acidosis
Decreased plasma renin, increased aldosterone
Increased insulin, glucagon, catecholamines
Antihypertensive effect

Front 14

What is the treatment of hyperkalemia?

Back 14

IMMEDIATELY:
Restore excitability
Redistribute K back within the cells

ASAP
Effect net removal of K

CHRONICALLY
Limit intake
Promote excretion

Front 15

What are ways that you can restore excitability to cells in hyperkalemia?

Back 15

Parenteral calcium gluconate; you can repeat this ONCE

This makes the membrane more stable..correcting the EKG problems

Front 16

What are ways that you can redistribute K back within the cells during hyperkalemia?

Back 16

Sodium bicarb (lowering the pH-->higher K in cells)

Insulin+glucose (stimulate the ATPase)

B2 agonists (stimulate the ATPase)

Front 17

What are ways that you can effect net removal of K in hyperkalemia?

Back 17

Sodium polystyrene sulfonate orally-->remove K from GI tract

Forced diuresis:

Dialysis

Front 18

Chronically, what are some ways to treat hyperkalemia?

Back 18

DIET!

Increased Na intake+diuretics

Mineralocorticoids

Sodium polystyrene sulfonate: bind K to increase excretion

Limit problematic drugs:
-ACEI/ARBs
-Aldo blockers
-NSAIDs

Front 19

What are some causes of spurious hypokalemia?

Back 19

Leukocytosis >100,000

Erythrocyte uptake when blood is drawn shortly after insulin administration

Not very common.

Front 20

What are some causes of hypokalemia?

Back 20

Alkalosis
Hyperadrenergic states
Insulin excess
Drugs: beta agonists, cAMP phosphodiesterase inhibitors, CCBs

Front 21

Why would a person in a hospital be hypokalemic?

Back 21

They're not taking it in and someone didn't remember to include K inside their fluids

Front 22

What are some causes of excess losses leading to hypokalemia?

Back 22

Renally: aldosterone driven

Extrarenal: GI disorders

Front 23

Why do excess mineralocorticoid states lead to hypokalemia?

Back 23

Mineralocorticoids stimulate aldosterone-->K loss

Also, they increase flow-->potassium loss that way

Front 24

Why do diuretics induce hypokalemia?

Back 24

Increase flow-->K loss

Induce RAA-->K loss

Diuretics themselves cause hypokalemia

Front 25

In what patients should you be especially concerned with diuretic induced hypokalemia?

Back 25

Patients with:
-Cardiac glycoside meds
-Acute MI
-Chronic heart disease

Front 26

What are characteristic lab findings in hyperaldosteronism?

Back 26

HTN

Front 27

What does licorice do to the kidneys?

Back 27

Allows cortisol to act as a mineralocorticoid-->hypokalemia

Front 28

In what situation are you acidotic and hypokalemic? Why?

Back 28

Type I renal tubular acidosis

There's an H/K antiporter on the apical side of the cells that doesn't work (H into lumen, K into tubule) It doesn't work...hypokalemia and acidemia

Front 29

What tubule function abnormalities can cause hypokalemia?

Back 29

Hypomagnesemia

Type I renal tubular acidosis

Front 30

What are some extrarenal causes of hypokalemia?

Back 30

Upper GI fluid losses (vomiting, gastric drainage)
Lower GI losses (diarrhea)
Hormones causing shifts away from the ECF: insulin, epinephrine, other beta agonists

Front 31

What is the mechanism of hypokalemia in upper GI fluid loss?

Back 31

You lose acid from the GI tract by vomiting or drainage

Then, you have:
compensatory hypokalemia from the kidney
volume depletion causing aldosterone release-->hypokalemia

Front 32

What is the relationship in the PC's and IC's in hypokalemia and alkalosis?

Back 32

Front 33

What is the effect of large volume diarrhea, fistulas, and enterostomies on potassium status? Acid/base status?

Back 33

Hypokalemia (losing K)

Acidotic (you're losing bicarbonate)

Front 34

In what conditions are you alkaline and hypokalemic?

Back 34

Upper Gi causes
Diuretics

Front 35

In what conditions are you acidotic and hypokalemic?

Back 35

Lower GI (losing bicarb with potassium)
Type 1 renal tubular acidosis (channel problems)

Front 36

In what situations are you hypertensive and hypokalemic?

Back 36

Primary mineralocorticoid

Front 37

What is the relationship between Cl/Bicarbonate and alkalosis?

How do you treat these alkaloses?

Back 37

Rule 1: you can't have both high Cl and HCO3 - they're both anions...your body doesn't want to have abnormally high anion levels, so one has to go
Rule 2:
There's a Bicarb/Cl exchanger in ICs of the CD

In metabolic alkalosis, you've got high HCO3-->low Cl

Treat this by giving Cl ions...which drives HCO3 out of the body!

Front 38

Why is Na not a reliable marker of volume status during metabolic alkalosis? What's a better use?

Back 38

Because there's so much bicarbonate around...it uses Na to neutralize the charge-->artificially high Na levels

You measure urine chloride

Front 39

What are causes of volume depletion/low urine cloride alkalosis?

Back 39

Upper GI loss (not losing bicarb)
Previous use of diuretics

Front 40

What are causes of high urine chloride/chloride insensitive alkalosis? What are other findings in this case?

Back 40

Primary excess mineralocorticoids

HTN

Front 41

What are the effects of hypokalemia?

Back 41

Arrhythmias
Decreased insulin release-->glucose intolerance (K is a stimulus for insulin release)
Muscle weakness
Renal dysfunction

Front 42

What is the treatment of hypokalemia?

Back 42

Give people oral K..not just K for the extracellular, but also for the intracellular space

Front 43

What are different K-sparing agents you can give to replace K?

Back 43

Amiloride
Triamterene
Spironolactone

Front 44

How should you go about correcting hypokalemia? Why?

Back 44

Give oral K

You can easily push someone to hyperkalemia with IV infusions

Front 45

What are causes of hypomagnesmia?

Back 45

Inadequate supply

Decreased absorption: (diarrhea, fistulas, small bowel resection)

Renal losses (DIURETICS, toxins)

Front 46

What are some causes of renal loss of magnesium?

Back 46

Diuretics!

Toxins: aminoglycosides, cis-platinum, Amphotericin B, cyclosporine

Front 47

What are some causes of hypermagnesemia?

Back 47

Decreased renal excretion

Front 48

What other condition is associated with hypomagnesemia?

Back 48

HYPOKALEMIA

Front 49

If you're hypokalemic, what should you order a lab for?

Back 49

Magnesium

Hypokalemia occurs with hypomagnesemia 40-60% percent of the time

Front 50

Other than hypokalemia, what other electrolyte imbalance occurs with hypomagnesemia? How?

Back 50

Hypocalcemia

Hypomagnesemia suppresses PTH secretion
Hypomagnesemia promotes resistance of bone to Ca2+ mobilizing effects of PTH

Front 51

What is the treatment of hypomagnesemia?

Back 51

Oral/parenteral:

Mg
K
Ca

Front 52

What are some symptoms of hypomagnesemia?

Back 52

Hypomagnesemia think SUPER EXCITED!

Arrhythmias
Seizures
Tetany, fasiculations
Positive chvostek's, trosseau's signs
Weakness, anorexia
Hypokalemia, hypocalcemia

Front 53

What are some symptoms of hypermagnesemia?

Back 53

Bradycardia
Hypotension
Muscle weakness, respiratory paralysis
Decreased/absent deep tendon reflexes
Sedation