Lec 8- Clinical lecture on salt

Question 1

What is hyponatremia?

Answer 1

• This is low sodium.
• The serum concentration of Na is lower than 135 mmol.
• it is estimated to effect 10% of patients in hospital.
• Associated mortality of up 20%.

Question 2

What are the symptoms of hyponatremia?

Answer 2

1. correlates to severity and rate of onset.

2. neurological: agitation, nausea, focal neurology and coma.

Question 3

What are the causes of hyponatremia?

Answer 3

1. True sodium loss, which can be caused by:
   - D&V
   - diuretics/ renal failure
   - Peritonitis
   - Burns/ CF
2. Na/ water in-balance.

Question 4

What is the reference range of serum osmolality?

Answer 4

275-295 mosm/kg (mol/kg)

Question 5

What is calculated osmolarity?

Answer 5

2 Na + glucose + urea (all in mol/L)

Question 6

What are some things that happen in right sided heart failure?

Answer 6

1. fatigue
2. increased peripheral venous pressure
3. Ascites
4. Enlarged liver & spleen
5. May be secondary to chronic pulmonary problems.
6. distended jugular veins
7. anorexia and complaints of GI distress
8. weight gain
9. dependent oedema

Question 7

What happens in hypovolemic hyponatremia?

Answer 7

1. Nonrenal loss
   - GI losses —> vomiting, diarrhoea, fistulas and pancreatitis
   - Excessive sweating
   - Third spacing of fluids —> ascites, peritonitis, pancreatitis and burns.
   - Cerebral salt- wasting syndrome
   - –> traumatic brain injury , aneurysmal subarachnoid haemorrhage and intra cranial surgery.
   - –> Must distinguish from SIADH.

Question 8

What is the urine Na for renal loss?

Answer 8

> 20 mmol/L +hypovolemic

Question 9

What is the urine Na for SIADH?

Answer 9

> 20 mmol/L + euvolemic

Question 10

What is the urine Na for renal failure?

Answer 10

> 20 mmol/L + hypervolemic

Question 11

What is the urine Na for GI/ skin loss?

Answer 11

< 10 mmol/L + Hypovolemic

Question 12

What is the urine Na for CCF, Nephrotic syndrome, liver failure ?

Answer 12

< 10 mmol/L + hypervolemic

Question 13

What is the treatment for low urine Na?

Answer 13

1. depends on the cause.
2. fluid restriction nearly always works.
3. pontine demyelination
   - This can occur with rapid correction of hyponatremia.
4. Infusion of hypertonic saline + furosemide can be used in symptomatic patients.