Potassium and Mg Disorders (Colby)

potassium

maintains intracellular fluid volume

GI

Where is K absorbed?

intracellulary

Where is K stored?

kidney.

Where is K excreted?

prox tubule and loop of henle

Where is K reabsorbed passively in the kidneys?

Na-K ATPase pump and aldosterone

What regulates K?

hypokalemia

Serum potassium concentrations < 3.5 mmol/L

-low K levels in the blood

etiology of hypokalemia

-Poor dietary intake

-Excessive loss from diarrhea or vomiting

-Over-excretion by kidneys

-Medications that deplete potassium

diuretics, mineralocorticoids, laxatives, potassium exchange resins

What medications deplete potassium causing hypokalemia?

-increases dietary intake

-switch from diuretics to K sparing diuretics

-dietary supplements of K

-rx formulations of K

How do you tx hypokalemia?

foods that increase K

-avacado

-bananas

-spinach

-potatoes

99 mg per tab

What is the OTC limit of K per tablet?

tachycardia and arrythmias

What can high doses of K do cause?

inorgnaic salts (lower bioavailability and higher elemental K).

-potassium chloride

-potassium bicarbonate

-potassium phosphate

potassium chloride

What is the most common inorganic salt K supplement? (neutral form)

basic formualation

potassium bicarbonate

potassium phosphate

less common, also supplements phosphate

Organic chelate forms (higher bioavailability)

-Potassium citrate

-Potassium gluconate

-Potassium aspartate

basic

Potassium citrate is a _________ formation.

good

Potassium gluconate has _______ absorption.

potassium aspartate

sports/performance supplement

1. Aldosterone receptor antagonists

2. Sodium channel blockers

What are the 2 types of K sparing diuretics?

NO

Do K sparing diuretics promote secretion of K into urine?

combined

K sparing diuretics are normally _________ with other diuretics.

aldosterone

-Mineralocorticoid and steroid hormone

-Causes retention of sodium and water

-Increases excretion of potassium

-Raises blood pressure

-Receptors found in heart and blood vessels and in kidney and brain

prevent

Blocking mineralocorticoid receptors can lower hypertension and ____________ potassium loss

Aldactone

Spironolactone

Spironolacton (Aldactone)

-Cyclized aldosterone derivative

-Selective aldosterone receptor blocker

-Widely used potassium-sparing diuretic

-Used in edema and heart failure

Inspra

Eplerenone

Eplerenone (Inspra)

-Cyclized aldosterone derivative

-Selective aldosterone receptor blocker

-Newer potassium-sparing diuretic

-Used in edema and heart failure

-Major interactions with CYP3A4

renal sodium channels

-Located in distal convoluted tubule and collecting ducts

-Reabsorb sodium from urine

-Contribute to function of Na+/K+ ATPase pump

-However, the sodium uptake capacity of this system is low

weak

Blocking renal sodium channels produce ________ anti-hypertensive effects.

Dyrenium

Triamterene

triamterene (Dyrenium®)

-Sodium-channel blocker

-Pteridine bicyclic ring (pyrimidine and pyrazine)

-Used in edema

-Weak potency (100-300 mg/day)

-Dosed twice per day

Midamor

Amiloride

amiloride (Midamor®)

-Sodium-channel blocker

-Open-ring analogue of triamterene

-100-fold more potent than triamterene (5-20 mg/day)

-Used in edema and hypertension

-Dosed once per day

hyperkalemia

Serum potassium concentrations > 5 mmol/L

-high K levels in the blood

etiology of hyperkalemia

-High dietary intake

-Decreased excretion by kidneys

-Metabolic disturbances such as metabolic acidosi

-Medications that increase potassium

NSAIDS, potassium sparing diuretics, ACE inhibitors, ARBs

What meds increase K?

Tx of hyperkalemia

-correct diet or dehydration

-utilize K binding resins

-can be emergency and cardiac stabilization may be required

potassium binding resins

-Sodium polystyrene sulfonate

-Patiromer

-Sodium zirconium cyclosilicate

potassium binders

-Cation-exchange polymers that are not absorbed in the GI

-Exchange calcium or sodium for potassium

-Increase fecal excretion of potassium

-Reduce levels of serum potassium

-May have effects on the kidneys or cause constipation

-May bind oral medications

Klonex

Sodium Polystyrene Sulfonate

Sodium Polystyrene Sulfonate (Klonex®)

-Insoluble polymeric resin

-Not absorbed in the GI

-Exchanges sodium for potassium

-Can bind oral medication

-Less use due to potential for fecal impaction

-Use with caution in renal impairment

Veitassa

Patiromer Sorbitex Calcium

Patiromer Sorbitex Calcium (Veitassa®)

-Insoluble polymeric resin

-Not absorbed in the GI

-Exchanges calcium for potassium

-Can bind oral medication

-Also binds magnesium which causes constipation

-Delayed onset, not for emergency

Lokelma

Sodium Zirconium Cyclosilicate

Sodium Zirconium Cyclosilicate (Lokelma®)

-Insoluble polymeric resin

-Not absorbed in the GI

-Exchanges sodium for potassium

-Can bind oral medication

-Delayed onset, not for emergency

Magnesium

-Regulates mitochondrial function, protein synthesis, and glucose metabolism

-Cofactor in many biochemical reactions, typically with ATP

-Imbalances affect the heart and neuromuscular function

-not regulated by hormones

kidney

where is Mg excreted?

prox tubulule, loop of henle and distal con tubule

Where is Mg reabsorbed?

bowel

Where is Mg absorbed?

hypomagnesemia

Serum magnesium concentrations < 1.7 mg/dL

-low Mg levels in the blood

etiology of hypomagnesemia

-Low dietary intake

-Poor intestinal absorption (most common)

-Over-excretion by kidneys

-Medications that deplete magnesium

diuretics, aminoglycosides, amphotericin, cisplatin

What drugs deplete Mg?

tx of Mg

-increase dietary intake

-switch from diuretics

-dietary supplements of Mg

almonds, cashews, kale, avocado, blackbeans

What foods increase Mg?

Inorganic salts (lower bioavailability and higher elemental Mg)

-Mag oxide

-Mag hydroxide

-Mag sulfate

-Mag chloride

Mg oxide

low bioavailability, supplement

-inorganic salt

mag hydroxide

laxative, antacid, inorganic salt

mag sulfate

common supplement, laxative and Epsom salt baths, inorganic salt

mag chloride

supplement inorganic salt

Organic chelate forms (higher bioavailability and lower element Mg)

-Mag citrate

-Mag gluconate

-Mag lactate

-Mag aspartate

Mag citrate

common supplement, mild laxative effect, organic chelate form

Mag lactate and gluconate

supplement of Mg, good tolerance

mag aspartate

sports/performance supplement Mg

hypermagnesemia

Serum magnesium concentrations > 2.4 mg/dL

-high Mg levels in the blood

etiology of hypermagnesemia

-Patients with chronic kidney disease

-Patients with multi-organ system failure on parenteral nutrition

-Supplement or antacid (magnesium hydroxide) over-use

challenging

Treatment of hypermagnesemia is ____________, focus on supportive care to address cardiovascular and neuromuscular effects