Hyponatremia ☺️

Question 1

Presentation

• early
• late

Answer 1

Early

• headache
• fatigue
• N+V
• confusion
• cramps

Severe

• seizures
• coma
• resp arrest

Question 2

What would the U&Es show if a patient had SIADH

What other signs and symptoms might they have?

Answer 2

• Na => low
• Plasma osmolality => low
• Urine Na, osmolality => high

Urea, creatinine => normal, not dehydrated

No postural hypotension (characteristic of Addisons)
Nausea, weakness, dizziness
Normal TFT, adrenal function

Question 3

Possible causes

Answer 3

Hypo hypo

• diuretic
• Addisons

Normo hypo
-SIADH (antipsychotics, mood stabilisers, lung cancer, infections)

Hyper hypo
-CF, LF, nephrotic

Question 4

How would you manage hyponatremia caused by SIADH

Answer 4

Fluid restriction
Demeclocycline - block ADH
Tolvaptan - ADH antagonist

Question 5

Investigations and diagnosis

• hypovolemic
• normovolemic
• hypervolemic

Answer 5

Hypovolemic
Urine Na 20+
-diuretics
-Addisons
-CKD

Urine Na U20 - extrarenal loss
-diarrhoea, vomit, sweat, burns

Euvolemic - urine Na 20+

• SIADH
• hypothyroid

Hypervolemia - urine Na U20

• HF, cirrhosis
• nephrotic
• excess fluids
• psychogenic polydipsia

Question 6

Consequences of

• untreated severe hyponatremia
• overrapid correction

Answer 6

Cerebral edema => brain herniation

Osmotic demyelination syndrome

Question 7

Management for chronic without severe symptoms

• hypovolemic cause
• normovolemic cause
• hypervolemic cause

Answer 7

Hypo - isotonic saline

• if serum Na rises => hypo hypo
• if serum Na falls => SIADH

Normo - fluid restriction
-address underlying cause

Hyper - fluid restriction, loop diuretics, vaptans
-address underlying cause

Question 8

Management for acute with severe symptoms

Answer 8

HDU/ICU monitoring

Hypertonic saline