Hyperkalemia/Hypokalemia Flashcards
How much of dietary K is excreted?
90-95
Where is the potassium excreted from the kidneys?
Principle cell
What controls K excretion?
Na delivery to distal tubule
- Metabolic alkalosis
- Aldosterone
How does increased distal Na?
Increased K excretion + increased H excretion
What push K into the cells?
Insulin +
Catecholamines
How does insulin push K into cells?
Activates Na/K pump
How do catecholamines (B2) work to put K into cell?
Activates Na/K pump
What does acidosis do to K in the body?
Shift of H+ into cells while K+ out of cell
- Hyperkalemia
How does hyperglycemia do hyperkalemia?
Solvent drag (water out) + water pulls K+ too
How does Cell lysis cause hyperkalemia?
Rhabdomyolysis, tumor lysis
- Also get Hyperphosphatermia + high serum uric acid
How does cell proliferation cause hypo kalemia?
Rapidly proliferating cells need more K+
What other labs should you check during hypokalemia?
Mag,
Urine Chloride
Ux (24h)
TTKG
What does magnesium show in K disorders?
Order for hypokalemia
Mech: Mag blocks K excretion
- Hypomag = increased K excretion
How does Urine Chloride lab show?
Hypokalemia, Metabolic alkalosis
- Saline Responsive: Urine Cl 20 (hyperaldosteronism)
What is the breakdown of Hyperkalemia?
Problem of either external balance or internal balance
What is the defect of internal balance of hyperkalemia?
Insulin def. Cell lysis Hypertonicity B2 adrenergic blockade Acidemia DKA Rhabdo, hemolysis, tumor lysis, burns, crush injury Hyperglycemia, B-Blockers, Metabolic acidosis, Resp acidosis
What is a defect external balance of hyperkalemia?
Decreased renal K excretion
- Acute + Chronic kidney disease
- Decreased distal sodium delivery
- Decreased distal tubular function
- Aldosterone deficiency
- Volume depletion, decreased EABV (CHF, cirrhosis)
- Interstitial nephritis
- ACEI/ARB, K-sparing (spironolactone, triamterene), Addision, RTA IV
What is pseudohyperkalemia?
Causes:
- severe leukocytosis/thrombocytosis/erythrocytosis
- Hemolysis during draw
- Processing delay
- Potassium leak from increased blood cells present
- Platelets release potassium during clotting process
What are the clinical manifestations of Hyperkalemia?
Cardiac toxicity (EKG, Arrythmias, conduction defects)
- Mild: Peaked T waves
- Moderate: Wide QRS complex, prolonged PR interval, shortened QT interval
- Severe: Widening of QRS complex (sine waves), absent P-wave
When to treat hyperkalemia?
Urgent K>6
How to treat high K?
C BIG KD2
- Ca gluconate
- Bicarb
- Insulin/Glucose
- Kayexalte
- Diuretic/Dialysis
What the defects of internal balance that cause hypokalemia?
Excess Inuslin
- Catechol excess
- Cell proliferation
- Poor diabetic management
- Aggressive lymphomas
- Various causes
What are the defects of external balance that cause hypokalemia?
- Inadequate intake
- GI/ Extrarenal losses
- Renal losses (hypertenisve)
- Renal losses (normotensive)
-Anorexia, malnutrition
-Diarrhea (NG tube= acid but NOT K) - Primary hyperaldosteronism (2=renal stenosis) Cushing, LIddle
Diuretics, osmotic diuresis, RTA, Bartter, Gitelman
What is the algorithm of hypokalemia?
1) Defect internal/external
2) Renal/Extrarenal losses
3) Hypertensive/normotensive
