K and Mg Disorders- Heemer

Normal serum conc of Potassium:

Normal serum conc of Potassium:

3.5-5 mEq/L

Functions of Potassium

• protein and glycogen synthesis

• cellular metabolism and growth

• determines membrane potentials

Potassium is regulated by what?

• diet

• excretion (GI and urinary)

• hormones

• acid-base balance

• body fluid tonicity

What hormones control potassium homeostasis?

• insulin

  • stimulates Na/K pump

• catecholamines

  • b-receptor

• aldosterone

  • stimulates renal excretion

How does acidosis and alkalosis effect potassium homeostasis?

acidosis- K leaves cell

alkalosis- K enters cell

How does hyperosmolality affect potassium homeostasis?

• K leaves the cell due to cell shrinkage and water movement

Hypokalemia usually occurs due to…

diuretics

4 causes of Hypokalemia:

1. diet

2. medications

3. loss of GI fluid

4. hypomagnesemia

Mild, Moderate, Severe symptoms of hypokalemia:

• mild- asymptomatic

• moderate- cramps, weak, myalgias

• severe- cardiac arrythmias, musculoskeletal

In hypokalemia, what should be corrected first?

hypomagnesemia

Nonpharm treatment of hypokalemia

• diet

• potassium salts

Hypokalemia ORAL Pharmacological treatment

• potassium phosphate, bicarb, or chloride

Hypokalemia IV Pharmacological treatment

• 10-20 mEq KCL diluted in 100mL NS

• 40-60 mEq KCL diluted in 1,000 mL 0.45% NaCl

When would we use IV treatments for hypokalemia?

• severe

• symptomatic

What type of diuretic is an alternative therapy for hypokalemia?

• potassium sparing diuretic

Major cause of Hyperkalemia

renal insufficiency

Other causes of Hyperkalemia:

• increase K intake

• decreased K excretion

• can’t respond to aldosterone

• cellular redistribution

Increased K+ intake is ALWAYS ASSOCIATED with…

renal insufficiency

Decreased K+ excretion is more common in _______.

Acute renal failure

Pseudohyperkalemia is usually caused by

• mistreatment of blood samples, cells burst, so K+ is released, and shows high potassium

Although hyperkalemia is usually asymptomatic, what is a sign or symptom?

• heart palpitations/ skipped heartbeat

Treatment of asymptomatic pts. w/ hyperkalemia

• loop diuretics

• cation exchange resins

3 examples of cation exchange resins

1. SPS

2. Patiromer

3. Sodium Zirconium Cyclosilicate

Treatments used for Severe/Symptomatic Hyperkalemia:

• calcium (chloride/gluconate)

• insulin

• albuterol

• sodium bicarbonate

• dialysis

Normal Serum range of Magnesium

1.4-1.8 mEq/L

Functions of Magnesium

• ATP synthesis

• protein synthesis

• cell membrane fxn

• PTH secretion

Causes of Hypomagnesemia

• alcoholism

• increased excretion

• decreased absorption

Hypomagnesemia is commonly seen with what other electrolyte disorders

• hypocalcemia

• hypokalemia

Signs/Symptoms of Hypomagnesemia

• neuromuscular

  • tetany, spasms, twitches

• cardiovascular

  • arrhythmias, HTN, sudden death

Hypomagnesemia Tx for Asymptomatic and Sympotomatic pts.

Asymptomatic- PO supplements

Symptomatic- IV MgSO4

Hypermagnesemia causes

• advanced renal failure

• enteral/parenteral nutrition

• Tx of Eclampsia w/ IV MgSO4

Signs/Symptoms of Hypermagnesemia

• neuromuscular

  • lowwww

  • sedation, hypotonia, coma, respiratory depression

• cardiovascular

  • hypotension, arrhythmias, bradycardia

Treatments of Hypermagnesemia

• calcium IV

• loop diuretics

• hemodialysis for ESRD