13. Electrolyte disorders Flashcards
What are the three main electrolyte disorders?
Disorders of potassium metabolism, disorders of sodium metabolism, and disorders of magnesium metabolism.
What is hypokalemia?
Hypokalemia is defined as serum potassium levels below 3.5 mmol/L.
What are the clinical manifestations of hypokalemia?
- Hypertension,
- arrhythmias,
- sudden cardiac death,
- weakness,
- rhabdomyolysis,
- alterations in acid-base balance (metabolic alkalosis),
- paralytic ileus.
What are the long-term effects of hypokalemia?
Mortality, risks of cardiovascular disease increase, renal cyst formation, and renal fibrosis.
What is pseudohypokalemia?
Artificial hypokalemia in blood sample - e.g in acute leukemia (leukocytes take up potassium).
What are the causes of redistribution hypokalemia?
Aldosterone increase, β2-adrenergic effects, anabolic state, insulin, and alkalosis.
What are the etiologies of hypokalemia?
- PseudohypoK
- Redistribubtion (shifts from ECF to ICF)
- Extrarenal loss
- Renal loss
What are the causes of renal loss hypokalemia?
- Medications such as thiazide, furosemide,
- bicarbonaturia, and
- magnesium deficiency (increased ROMK-mediated secretion).
- genetic diseases (bartter, gitelman)
- hormonal diseases (liddle, cushing)
What is the definition of hyperkalemia?
Hyperkalemia, if Se K > 5.5 mmol/L.
What are some clinical manifestations of hyperkalemia?
- muscle weakness (diaphragmatic muscle-respiratory failure),
- metabolic acidosis,
- ECG changes: peaked T waves, STD, prolonged QRS, ventricular fibrillation, etc.
What are the etiologies of hyperkalemia?
- PseudohyperK
- Redistribution
- Excess intake
- Impaired renal excretion
What are the causes of pseudohyperkalemia?
Hemolysis, difficult phlebotomy.
What are the causes of impaired renal excretion hyperkalemia?
- Medication such as ACEi, ARB, spironolactone,
- obstructive uropathy,
- aldosterone deficiency/resistance, Addison’s disease, pseudohypoaldosteronism.
What is the treatment for severe hyperkalemia?
- 10% Ca-gluconate 10mL/10min
- insulin (4 to 10U/h) with 10% dextrose iv,
- hemodialysis,
- β2 agonist by nebulizer (albuterol).
What are the methods for potassium removal in hyperkalemia treatment?
- Resin (sodium/calcium polystyren-sulfonate) 15-60g/day (per os or as retention enema),
- diuretics such as furosemide and thiazide.
What are the treatments for chronic hyperkalemia?
Review of medication, dietary restrictions, intermittent resin/Patiromer treatment, fludrocortisone.
What is the definition of hyponatremia?
Se Na < 135 mmol/L.
What are the clinical signs of hyponatremia?
- Headache,
- yawning, lethargy,
- nausea,
- reversible ataxia,
- psychosis,
- seizures, cerebral edema, tentorial herniation,
- respiratory depression.
What is the differential diagnosis for hyponatremia?
- Pseudohyponatremia,
- translocational hyponatremia (movement of water from ICF to ECF)
- real/hypotonic hyponatremia. (serum Na AND osm decrease)
Etiology of hyponatremia
- Hypovolemia : Renal / extrarenal losses
- Euvolemia : glucocorticoid deficiency, hypothyroidism, SIADH
- Hypervolemia : Renal loss, water retention
What is the diagnostic criteria for SIAD?
- Se Osm ↓,
- Urinary Osm > 100 mOsm /kgH2O,
- Hyponatremia
- euvolemia.
What is the treatment for symptomatic hyponatremia?
NaCl infusion in 1 hour ±furosemide
What is the risk associated with rapid correction of SeNa in the treatment of hyponatremia?
Central pontine myelinolysis (CPM) - osmotic demyelination.
What is hypernatremia?
Hypernatremia is defined as a serum sodium level greater than 145 mmol/L.
What are the clinical manifestations of hypernatremia?
- altered mental status, irritability, restlessness
- lethargy,
- seizures, muscle twitching, spasticity
- hyperreflexia,
- fever,
- nausea, vomiting,
- labored breathing.
What is the treatment for hypernatremia?
The treatment for hypernatremia involves frequent control of serum sodium levels, with a maximum correction of 8 mmol/L per 24 hours. Treatment of too rapid correction involves dextrose IV and desmopressin.
What are the risk factors for hypernatremia?
The risk factors for hypernatremia include the elderly, infants, hypertonic infusions, tube feeding, mechanical ventilation, uncontrolled diabetes mellitus, and polyuric disorders.
What are the causes of hypernatremia?
- Hypovolemic : extrarenal and renal loss (diuretics, osmotic diuresis -DM)
- Euvolemic : diabetes
- Hypervolemic : sodium gain - hyperaldosteronism, cushing’s
What is the treatment for hypernatremia?
- Hypo / euvolemic : correction of water deficit
- Removal of Na (furosemide, hemodialysis)
What is the maximum speed of correction for hypernatremia?
2 mmol/L/hour, 10 mmol/L/day (caution: cerebral edema).
What are the causes of hypermagnesemia?
Renal failure, Mg supplementation, familial hypocalciuric.
What is the normal value of serum magnesium in women?
0.75 to 1.0 mmol/L.
What are the causes of hypermagnesemia?
- Renal failure,
- Mg supplementation,
- familial hypocalciuric hypercalcemia,
- acromegaly,
- adrenal insufficiency.
What are the symptoms of hypermagnesemia?
Deep tendon reflexes decrease, paralysis
What is the treatment for hypermagnesemia?
Ca-gluconate iv.
What are the causes of hypomagnesemia?
- Decreased intake, malabsorption,
- increased excretion : polyuric disease, prolonged infusion with excessive Na content, primary aldosteronism, Gitelman syndrome
- medication (aminoglycosides, calcineurin inhibitors, amphotericin, thiazide
- other (acute pancreatitis, chr. alcoholism, idiopathic).
What are the symptoms of hypomagnesemia?
Weakness, hyperreflexia, tremor, spasm, ECG: prolonged QT interval, ST depression, risk of arrhythmias ↑.
What is the treatment for hypomagnesemia?
MgSO4 iv., per os Mg-salts.
