Lecture 7 - Hypo And Hypernatremia Flashcards

1
Q

What is considered hypernatremia?

A

Na+ > 146mmol/L

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2
Q

What is the major cause of hypernatraemia, fluid loss or Na+ gain?

A

Change in fluid levels

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3
Q

What are some causes of hypernatremia?

A

Uncontrolled diabetes
Fluid loss without replacement (sweating, burns and vomiting)
Diabetes Insipidus (large vol of dilute urine)
Incorrect IV fluid replacement
Primary aldosterone

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4
Q

What is considered hyponatremia?

A

Na+ <135mmol/L

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5
Q

Where is hyponatremia very common?

A

Hosptial patients

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6
Q

What are the symptoms of Hyponatremia?

A

Agitation
Nausea
Focal neurology (affects nerves in brain)
Coma
Lose consciousness
Seizures
Feeling weak

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7
Q

What are some causes of Hyponatremia leading to water loss?

A

Diuretics (thiazides)
Water overload or retention
Inc ADH levels
Inc plasma Osmolality (mannitol, glucose)

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8
Q

What are some causes of hyponatremia that lead to True Na+ loss?

A

Diarrhoea and vomitting
Diuretics/renal failure
Peritonitis
Burns

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9
Q

How do you approach treating a patient with low Na+? (Hyponatraemia)

A

Always look at the Osmolality of the blood first

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10
Q

What is the normal range of serum osmolality?

A

275 - 295mosm/kg

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11
Q

How do you calculate osmolality?

A

Osmolarity = (2 x Na conc) + glucose conc + urea conc (sometimes add K+)

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12
Q

In the osmolarity equation why do you multiply the sodium conc by 2?

A

Since Na always accompanied by Cl-

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13
Q

If a patients serum osmolarity is hyper osmotic when they have hyponatraemia what does this indicate?

A

Its not a kidney related issue

usually due to mannitol , hyperglycaemia

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14
Q

If someone is hyponatraemic what do you need to asses?

A

Their extracellular fluid volume

Are they fluid depleted or oedematous?

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15
Q

What is indicated if a patient is oedematous with hyponatremia with the serum being Hypoosmotic?

A

Blood not filtered properly

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16
Q

What is indicated in hyponatraemia oedematous patients with a low urine conc of Na+?

A

Acute/chronic renal failure

17
Q

What is indicated in hyponatraemia oedematous patients with a high urine conc of Na+?

A

Nephrotic syndrome
Cirrhosis
Cardiac failure

18
Q

What is nephrotic syndrome?

A

Patients lose albumin into the urine from the blood
This leads to oncotic pressure decreasing so less water drawn from interstitium back into blood

19
Q

If a hyponatraemic patient is fluid depleted what is indicated by the urine conc of Na+ being low?

A

Sodium is not being lost from the kidneys
So could be a bleed from the Gi tract or skin

20
Q

If a hyponatraemic patient is fluid depleted what is indicated by the urine conc of Na+ being high?

A

Losing too much sodium in urine

(Cerebral salt wasting)

21
Q

What is cerebral salt wasting syndrome?

A

When a traumatic brain injury leads to losing salt from body

22
Q

What could be the cause of hyponatraemia in a patient that has normal extracellular fluid volume with a low sodium conc in urine?

A

Severe Polydipsia

23
Q

What could be the cause of hyponatraemia in a patient that has normal extracellular fluid volume with a high sodium conc in urine?

A

SIADH
Glucocorticoid deficiency
Acute/chronic renal failure

24
Q

Generally how do treat hyponatraemia?

What about hypernatraemia?

A

Hyponatraemia = restrict water intake

Hypernatraemia = give fluids

25
Q

What potential complication can occur with rapid developing hyponatraemia?

A

Pontine demyelination

26
Q

What is pontine demyelination?

A

Myelin cells around nerves swell which can damage nerves

This is due to lots of water being present

27
Q

How can hyponatremia be specifically treated?

A

Infuse hypertonic saline
Furosemide

28
Q

A hyponatraemic patient has:
-decreased serum osmolarity
-increased urine osmolarity
-high urine Na+ conc

What is this condition potentially indicative of?

A

They are Hypoosmotic so have taken on to much fluid (low serum osmolarity)

Lots of water gone into blood instead of urine (high urine osmolarity)

Body tries eliminating more Na+ to get rid of as much water

Likely have SIADH

29
Q

How can valproate and carbamazepine lead to SIADH?

A

Can cause excess ADH release

30
Q

What are Valproate and carbamazepine often used to treat?

A

Epilepsy

31
Q

What is the main ion in the Intracellular fluid compartment?

What is the main ion in the Extracellular fluid compartment?

A

ICF = K+

ECF = Na+ and Cl-

32
Q

What body fluid compartmen is being diluted in dilutional hyponatremia?

A

Often the ECF

33
Q

Which organ is of major concern in dilutional hyponatremia?

A

Brain