3.26 Abnormalities of sodium and potassium

Sodium 135-145
1. Hypernatraemia
  1. Signs and symptoms
    1. Dehydrated, thirsty, weak and tired
    2. Irritable, confused, low GCS, fitting
  2. Causes
    1. not enough water
      1. low intake
      2. increased loss
        dermal - sweating, burns
        GI - D/V
        renal
        diuretics
        Diabetes insipidus - polyuria
        hyperaldosteronism
        osmotic diuresis e.g. DKA
    2. too much sodium - iatrogenic (saline)
  3. Management
    1. 1. Oral water 2. IV Dextrose (5%) 3. IV saline
2. Hyponatraemia
  1. Signs and symptoms
    1. anorexia, nausea, malaise
    2. headaches, irritable, low GCS, fitting
  2. Causes
    1. dehydration
      1. urinary sodium >20mmol/L
        addisons
        diuretics
        osmotic e.g DKA
        polyuric renal failure
      2. low urinary sodium: D/V, burns, sweating...
    2. euvolaemia
      1. urine osmolality >500: SIADH. Rx = ADH antagonist e.g. domeclocycline
      2. low osmolality: primary polydipsia, glucocorticoid deficiency
    3. fluid overload
      1. Nephrotic syndrome
      2. Cardiac, liver or renal failure
  3. Management
    1. treat cause
    2. fluid restriction
    3. saline*
      Anotações:
      - no more than 15mmol increase per day, due to risk of central pontine myelinosis
Potassium 3.5-5
1. Hyperkalaemia
  1. Signs and symptoms
    1. palpitations, chest pain, light headed
    2. weakness
  2. investigations
    1. ECG: Tall T waves and small P waves; VF
  3. Causes
    1. drugs e.g. K+ sparing diuretics
    2. endocrine e.g. addisons
    3. trauma e.g. rhabdomyolysis
    4. iatrogenic
    5. metabolic e.g. acidosis
  4. Management
    1. Acute
      1. 1. protect mycardium with IV calcium gluconate
      2. 2. push K+ into cells with IV insulin + dextrose; nebulised salbutamol;
      3. 3. Prevent absorption with calcium resonium
      4. 4. Remove K+ with dialysis
    2. Chronic: treat cause
2. Hypokalaemia
  1. Signs and symptoms
    1. neurological signs resembling LMN lesion: weakness, hypotonia, hyporeflexia, tetany
    2. palpitation and lightheadedness
  2. Causes
    1. Infection -> D/V
    2. Metabolic: alkalosis
    3. medication e.g. diuretics, steroids
    4. endocrine e.g. cushings, conns
  3. Management
    1. K+ replacement.
      Anotações:
      - if giving IV, give no more than 20mmol/h, and no more than 40mmol/L

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3.26 Abnormalities of sodium and potassium

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