Potassium Disturbances

Question 1

What is the normal extracellular potassium level?

Answer 1

3.5-4.5 mmol/L

Question 2

Acute vs Chronic potassium disorder

Answer 2

Acute <48hrs
Chronic >48hrs

Question 3

How does insulin, long-standing alkalemia, hyertonicity, exercise, and cell integrity effect potassium levels?

Answer 3

Insulin: Causes a potassium intracellular influx
Alkalemia: hypokalemia
Hypertonicity: Hyperkalemia
Exercise: Transient potassium shift extracellularly
Cell integrity: Ischemia causes hyperkalemia

Question 4

External factors that effect potassium levels: Kidney elimination, Metabolic Acidosis, Metabolic alkalosis, Aldosterone, Glucocorticoids, Magnesium deficiency

Answer 4

Kidney Elimination: Eliminates 90% of dietary K+
Metabolic Acidosis: inhibits K+ secretion, hyperkalemia
Metabolic Alkalosis: stimulates K+ secretion, hypokalemia
Aldosterone: increase in K+ stimulates aldosterone, reduces plasma K+, hypokalemia
Glucocorticoid: enhances renal K+ excretion, hypokalemia alkalosis
Mag deficiency: renal potassium wasting.

Question 5

Five main causes of hyperkalemia with examples

Answer 5

1. Excessive potassium intake (typically results from IV administration)
2. Abnormal K+ distribution: Tumor lysis syndrome, rhabdo, burns, hemolytic transfusion reactions, mesenteric ischemia
3. Pharmaceuticals: Digoxin, Succ
4. Acute renal failure
5. Pseudohyperkalemia: hemolyzed blood sample

Question 6

Definition and causes (3) of acute hypokalemia

Answer 6

Hypokalemia developing over hours
DKA: Patients can have a normal K+ level initially, with delivery of insulin K+ shifts back into cells producing hypokalemia
Pharmaceuticals: Albuterol, epinepherine
Therapeutic hypothermia: hypokalemia occurs in cooling phase, careful of replacement due to rebound hyperkalemia.

Question 7

Cardiovascular, Neuro, and metabolic manifestations of hyperkalemia

Answer 7

Cards: Peaked T-wave, loss of p-wave (Sine wave), prolonged PR, and widened QRS, V-fib, asystole, if K >6.5 regardless of EKG treat emergently
Neuro: parathesias, weakness, paralysis, diaphragm spared, decreased reflexes
Metabolic: decrease renal ammoniagenesis, produces hyperchloremic metabolic acidosis. Prevents kidneys ability to excrete

Question 8

Cardiovascular, Neuromuscular, and metabolic clinical manifestations of hypokalemia

Answer 8

Cards: ST depression, decreased T wave amplitude, increased U wave amplitude, increase dig toxicity, ventricular ectopy
Neuro: weakness, myalgias, paralysis, rhabdo
Metabolic: glucose intolerance, increased protein catabolism, polydipsea, polyuria, metabolic alkalosis

Question 9

What is hyperkalemic Periodic paralysis

Answer 9

Rare
Mutation of skeletal muscle Na+ channels
Precipitated by exercise, fasting, cold, and potassium administrations
Prevented with carbs

Question 10

What is refeeding syndrome?

Answer 10

Glucose initiated hyperinsulinemia, causing K to shift hypokalemia

Question 11

What is hypokalemic periodic paralysis

Answer 11

Inherited, sporadic, or thyrotoxic
Muscle weakness following acute hypokalemia
Can cause ventilatory failure or cardiac arrhythmia
Can be caused by ingestion of carbs, salt intake, or exercise
Manage with potassium

Question 12

What is thyrotoxic periodic paralysis

Answer 12

Accompanied by hypophosphatemia
Causes hypokalemia
Manage like hyperthyroidism

Question 13

What are the labs and questions you want to ask to assess for Hypokalemia or Hyperkalemia

Answer 13

EKG
CMP
GFR and Crt
Aldosterone
Medications

Question 14

Management of Hyperkalemia

Answer 14

Treat if K >6.5
Insulin R 10 units with D5 amp
Calcium gluconate 1g/10mls for cardiac protection
Albuterol neb 20mg/4mls for temporary decrease
Bicarb (only useful in severe metabolic acidosis)
Diuretics
K Binder (kayexalate)
HD

Question 15

Management of Hypokalemia

Answer 15

Replete low K+ 10meq corrects by 0.2 mmol K+