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POTASSIUM (HYPERKALAEMIA (Clinical Sx (Depolarisation of memebranes (ECG…

- - - - Governs uptake of K+ into cells
        
        Stimulated by
        
        B-adrenergic stimulation
        
        Salbutamol
        
        Insulin
        
        Rx of DKA
        
        Theophyllines
        
        Stimulation of Na/K/ATPase = decreased ECF K+ and therefore HYPOkalaemia
        
        Inhibited by
        
        a-adrenergic stimulation /B-adrenergic blockers
        
        Inhibition of Na/K/ATPase = increased ECF K+ and therefore HYPERkalaemia
    - - H+/K+ exchanger
        
        Acidosis
        
        HYPERkalaemia due to attempted maintenance of pH by increasing intracellular H+
        
        Alkalosis
        
        HYPOkalaemia due to attempted maintenance of pH by decreasing intracellular H+ and increasing ECF H+
    - - Usual intake 80-150mmol/day
        
        Fruit
        
        Vegetables
        
        Legumes
    - - 90% reabsorbed in proximal tubule
        
        passive in proximal tubule
        
        via Na/K/2Cl in TAL
      - <10% delivered to distal tubule
        
        principal cells in collecting duct
        
        aldosterone
        
        secreted in response to RAAS activation
        
        increases K+ LOSS
        
        HYPOkalaemia
        
        conserves Na+
        
        Increased with ATII and some drugs
        
        also effected by pH
        
        H+ and Na+ are interchangeable in the exchanger and therefor if acidotic it will promote H+ excretion and K+ conservation and HYPERkalaemia
    - - Normal excretion is 10% of daily K+ intake secreted via stool
      - Prolonged vomitting
        
        Sodium depletion
        
        RAAS
        
        aldosterone
        
        increased K+ loss
        
        Hypokalaemia
        
        Only 5-10mmol/L K+
      - Prolonged diarrhoea
        
        10-30mmol/L K+
        
        HYPOkalaemia
- - - - <2.5mmol/L can cause muscle weakness
      - Increased atrial/ventricular ectopics
  - - - DIURETICS
        
        Loop
        
        Thiazide
    - - Intrinsic
        
        Liver failure
        
        Heart failure
        
        Nephrotic syndrome
        
        Cushing's syndrome
        
        ACTH tumour
      - Exogenous
        
        Corticosteroids (mineralocorticoid action)
        
        Liquorice
        
        Carbenoxolone
    - - B-adrenergic stimulation
      - Beta-agonist
      - Alkalosis
      - Insulin treatment
    - - Vomit
      - Diarrhoea
      - Laxative abuse
      - Ileostomy
  - - - Increase intake of fresh fruit/vegetables
      - Potassium supplement (20-40mmol OD)
        
        Slow K
        
        Effervescent
    - - Spironolactone
    - - Add 30mmol of K+ to fluid
- - - - Acute kidney injury
      - Drugs
        
        Spironolactone
        
        ACE inhibitors
        
        Ciclopsorin
        
        Heparin
        
        B-blockers
      - Aldosterone deficiency
      - Addison's disease
    - - Decreased Na/K ATPase
        
        Acidosis
        
        DKA
      - Rhabdomyolysis
      - Tumour lysis
      - +++ exercise
      - Insulin deficiency
    - - KCl
      - Salt substiutues
      - Blood transfusion
    - - Leukaemia
      - Infectious mono
      - Fist clenching during phlebotomy
      - Haemolysis of blood sample
  - - - Cardiac excitability
      - Hypotension
      - Bradycardia
      - ECG changes
        
        Tented T waves
        
        Reduced p wave
        
        Widened QRS
        
        Sine wave pattern (last change before cardiac arrest)
  - - - Calcium gluconate
        
        Bicarbonate/insulin and glucose
        
        B-agonist (Salbutamol)
        
        Sodium polystyrene syldonate
        
        Loop diuretic
        
        Dialysis