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Endocrinology > Hyper/Hypo - Natraemia > Flashcards

Hyper/Hypo - Natraemia Flashcards

1
Q

What are symptoms are hypernatraemia?

A
  • Lethargy
  • Thirst
  • Weakness
  • Irritability
  • Confusion
  • Coma
  • Fits
  • Signs of dehydration
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2
Q

What will the blood tests show in a case of hypernatraemia?

A
  • Increased Na+
  • Increased PCV (packed cell volume)
  • Increased albumin
  • Increased urea
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3
Q

What are the causes of hypernatraemia?

A
  • Fluid loss without water replacement (diarrhoea, vomiting, burns)
  • Diabetes insipidus
  • Osmotic diuresis in diabetic coma
  • Primary aldosteronism (high BP, high Na, alkalosis)
  • Iatrogenic - excess saline given
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4
Q

What is the management for hypernatraemia?

A
  • Give water orally if possible
  • If not, give glucose 5% IV slowly (1L/6hr) guided by urine output and plasma Na+
  • Use 0.9% saline if hypovolaemic
  • Avoid hypertonic solutions
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5
Q

What are some symptoms of hyponatraemia?

A
  • Anorexia, nausea, malaise
  • Headache, irritability, confusion, weakness, low GCS and seizures
  • Increased risk of falls in the elderly
  • Cardiac failure or oedema may point to a cause
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6
Q

What are some artefactual causes of hyponatraemia?

A
  • Blood sample taken from a drip arm
  • High serum lipid/protein content
  • Hyperglycaemia (normal serum osmolarity)
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7
Q

What are some iatrogenic causes of hyponatraemia?

A
  • If 5% glucose is infused continuously without 0.9% saline. Glucose is quickly used so blood becomes hypotonic.
  • Especially those on thiazides, women and those undergoing stress (surgery, sepsis)
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8
Q

What are some causes of hyponatraemia in a dehydrated patient with high urinary concentration of Na+? (>20mmol/L)

A
  • Na+ and water are being lost from the kidneys
    eg
  • Addison’s disease
  • Renal failure
  • Diuretic excess
  • Osmolar diuresis (high glucose, high urea also)
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9
Q

What are some causes of hyponatraemia in a dehydrated patient with low urinary concentration of Na+? (<20mmol/L)

A
  • Na+ and water are being lost from somewhere other than the kidneys
  • Diarrhoea, vomiting
  • Fistulae
  • Burns
  • Rectal villous adenoma
  • Small bowel obstruction
  • Trauma
  • CF
  • Heat exposure
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10
Q

What are some causes of hyponatraemia in a hydrated patient who is oedematous?

A
  • Nephrotic syndrome
  • Cardiac failure
  • Liver cirrhosis
  • Renal failure
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11
Q

What are some causes of hyponatraemia in a hydrated non odematous patient, who high low urine osmolality (>100mmol/KG)

A
  • SIADH
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12
Q

What are some causes of hyponatraemia in a hydrated non odematous patient, who has low urine osmolality <100mmol/KG?

A
  • Water overload
  • Severe hypothyroidism
  • Glucocorticoid deficiency
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13
Q

What investigations would you undertake?

A
  1. Serum osmolarity - to exclude hyperglycaemia as a cause
  2. Urine osmolarity
  3. Urine sodium
    - TFT’s
    - Assessment of cortisol (0900 cortisol or synacthen test)
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14
Q

What is the treatment for asymptomatic chronic hyponatraemia

A
  • Fluid restriction
  • ADH antagonist (demeclocycline) may be required
  • If hypervolaemia (cirrhosis, congestive heart failure) treat underlying cause
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15
Q

What is the treatment for acute/symptomatic hyponatraemia?

A
  • Cautious rehydration with 0.9% saline
  • Aim for MAX serum Na+ rise 15mmol/day if chronic, and 1mmol/hr if acute
  • Use furosemide if not hypervolaemic to prevent fluid overload
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16
Q

What is the treatment for emergency hyponatraemia

A
  1. IV infusion 150ml with 3% hypertonic saline over 20 minutes
  2. Furosemide
17
Q

What is the major complication with treating hyponatraemia?

A

Central pontine myelinolysis

- Irreversible and fatal pontine demyelination

18
Q

What does the diagnosis of SIADH require?

A
  • Concentrated urine (Na+>20mmol, osmolality>100mmol/KG)
  • Hyponatraemia
  • Low plasma osmolality (<260mmol/KG)
  • Absence of hypovolaemia, oedema and diuretics
19
Q

What are the causes of SIADH?

A

Malignancy - Lung small cell, pancreas, prostate, thymus, lymphoma
CNS Disorders - Meningitis, stroke
Chest disease - TB, pneumonia
Endocrine disease - Hypothyroidism
Drugs - SSRI’s, opiates, cytotoxics, psychotropics
- HIV
- Trauma or surgery

20
Q

What is the treatment for SIADH?

A
  • Treat the cause
  • Fluid restriction
  • Salt
  • Loop diuretics
  • Demeclocycline is used rarely
  • Vasopressin receptor antagonists are emerging

Endocrinology (11 decks)

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