L6: Potassium Disorders Flashcards
Levels of K
High Intracellular concentration of K+ is necessary for several cellular functions.
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Routes for K+ excretion
Routes for K+ excretion are:
- The KIDNEY (primary route).
- The colon.
Renal Handling of Potassium
Renal handling of K+ involves
① Filtration
② Reabsorption
③ Secretion.
Renal Handling of Potassium
- Filtration
K+ is freely filtered at the glomerulus.
Renal Handling of Potassium
- Reabsorbtion
Renal Handling of Potassium
- Secretion
Factors affecting K Execretion
Renal Handling of Potassium
- Intake
Renal Handling of Potassium
- hormones
Renal Handling of Potassium
- Acid-Base Balance
Renal Handling of Potassium
- Anions
Renal Handling of Potassium
- Diuretics
Def of Hypokalemia
Serum potassium level < 3.5 mEq/L.
Psedo-Hypokalemia
- Hypokalemia is the result of K+ uptake by white blood cells when the sample is stored at room temperature. WBC (>75 x 109/L) as in AML (acute myeloid leukemia).
Etiology of Hypokalemia
Etiology of Hypokalemia
- Insufficient Intake
Etiology of Hypokalemia
- Intracellular Shift
Def of Hypokalemic periodic paralysis
- A rare inherited disorder characterized by episodes of muscle weakness in one or more limbs accompanied by low serum K+ levels
Types of Hypokalemic periodic paralysis
① Familial Periodic Paralysis
② Thyrotoxic Periodic Paralysis.
Etiology of Hypokalemic periodic paralysis
- Autosomal dominant inheritance
- spontaneous mutations
Potential triggers of Hypokalemic periodic paralysis
- Physical activity
- Night rest
- High carbohydrate diet
- Alcohol intake
Etiology of Hypokalemia
- Renal Loss
Etiology of Hypokalemia
- Renal Loss (Drugs)
① Diuretics (thiazides - loop diuretics - osmotic diuretics).
② Beta-2 adrenergic agonists.
③ Glucocorticoids.
④ Catecholamines
Etiology of Hypokalemia D2 Renal Loss
- Hypokalemic Disorders
Etiology of Hypokalemia D2 Renal Loss
- Hypokalemic Disorders (Hypertensive)
Etiology of Hypokalemia D2 Renal Loss
- Hypokalemic Disorders (Hypotensive)
Etiology of Hypokalemia
- Non-Renal Loss
Most common causes of hypokalemia
① Losses caused by diuretics
② Gastrointestinal disorders.
CP of Hypokalemia
CP of Hypokalemia
- manifestations of the cause
E.g., Cushing’s syndrome.
CP of Hypokalemia
- Manifestations of Hypokalemia
CP of Hypokalemia
- Neuromuscular
CP of Hypokalemia
- CVS
① Arrhythmias
② Abnormal contractility
③ Potentiation of digitalis toxicity
CP of Hypokalemia
- metabolic
CP of Hypokalemia
- Renal
① Nephrogenic diabetes insipidus
② Chronic tubulointerstitial nephritis.
Dx of Hypokalemia
Dx of Hypokalemia
- Serum Potassium Level
Serum K+ <3.5 mEq/l means hypokalemia.
Dx of Hypokalemia
- ECG
Dx of Hypokalemia
- Determine Cause
Dx of Hypokalemia
- Algorithm
Algorithm for Dx of Hypokalemia
- Urine K
Algorithm for Dx of Hypokalemia
- After Checking BP
Algorithm for Dx of Hypokalemia
- Normal BP with decreased HCO3
Algorithm for Dx of Hypokalemia
- Normal BP with Increased HCO3
Algorithm for Dx of Hypokalemia
- Increased BP with Increased Renin & Increased aldosterone
Algorithm for Dx of Hypokalemia
- Increased BP with Decreased Renin & Increased aldosterone
Algorithm for Dx of Hypokalemia
- Increased BP with decreased Renin & decreased aldosterone
TTT of Hypokalemia
TTT of Hypokalemia
- repletion of K
Repletion of K in Hypokalemia
- Mild
Repletion of K in Hypokalemia
- Moderate
Repletion of K in Hypokalemia
- Severe
High concentrations of IV potassium can cause local venous irritation and potentially lead to cardiac arrhythmias.
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TTT of Hypokalemia
- TTT Cause
Def of Hyperkalemia
Serum K+ >5.5 mEq/L.
Pseudo-Hyperkalemia
Cells release K+ in vitro due to:
- Thrombocytosis
- Severe leukocytosis
- RBCs hemolysis (e.g., trauma from tourniquet application).
Etiology of Hyperkalemia
Etiology of Hyperkalemia
- high Intake
① Diet - Supplements.
② K+ containing salt substitutes.
Etiology of Hyperkalemia
- Transcellualr Shift of K+
Etiology of Hyperkalemia
- Impaired Renal Excretion
Hyperkalemia D2 Impaired Renal Excretion
- primary Renal Disease
◈ Acute kidney injury (especially severe oliguric AKI)
◈ Advanced CKD.
Hyperkalemia D2 Impaired Renal Excretion
- Hyperkalemic renal tubular acidosis (RTA)
Hyperkalemia D2 RTA
- Decreased aldosterone secretion
Hyperkalemia D2 RTA
- decreased aldosterone responsivness
CP of Hyperkalemia
CP of Hyperkalemia
- Asymptomatic
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CP of Hyperkalemia
- symptomatic
CP of Hyperkalemia
- Neuromuscular
CP of Hyperkalemia
- Cardiac
- Arrhythmias (e.g., heart block - ventricular fibrillation).
- Palpitations.
CP of Hyperkalemia
- Metabolic
Metabolic acidosis (non-anion gap).
CP of Hyperkalemia
- GIT
Nausea or vomiting.
Dx of Hyperkalemia
Dx of Hyperkalemia
- Serum Potassium Level
Dx of Hyperkalemia
- ECG
Dx of Hyperkalemia
- Earliest Sign in ECG
Peaked T Wave
Dx of Hyperkalemia
- Changes in waves/intervals/segments
Dx of Hyperkalemia
- Arrhythmias
- There is a weak correlation between serum K+ levels & the severity of ECG changes.
- Findings are more likely to occur with rapid-onset hyperkalemia.
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Dx of Hyperkalemia
- Investigations of the cause
Dx of Hyperkalemia
- ABG
Blood gases often shows metabolic acidosis.
TTT of Hyperkalemia
TTT of Hyperkalemia
- COUNTERACTING MEMBRANE EFFECTS OF HYPERKALEMIA
TTT of Hyperkalemia
- PROMOTING CELLULAR UPTAKE OF K+
TTT of Hyperkalemia
- OTHER MEASURES
TTT of Hyperkalemia
- Remove K from Body
① Potassium-lowering resins (potassium binders) or
② Loop diuretics or
③ Dialysis (to remove K+ rapidly in patients with kidney impairment).
TTT of Hyperkalemia
- Medications & supplements review
① Discontinue or modify dosing of medications that may be contributing to hyperkalemia.
② Stop K+ containing salt substitutes & K+ supplements.
TTT of Hyperkalemia
- Diet
Low K+ diet.