Hyponatraemia

Question 1

What is hyponatraemia?

Answer 1

1. Low plasma sodium, defined as less than 135mmol/L

2. Is the most common disorder of electrolyte encountered

Question 2

What kinds of patients present with hyponatraemia?

Answer 2

1. Acute neurological conditions
2. 50% of patients with subarachnoid hemorrhage
3. Elderly
4. Patients with respiratory tract infections
5. History of alcohol xs and who are treats d with thiazide diuretics

Question 3

Most cases of hyponatraemia are mild and relatively assymptomatic what are the more serious consequences?

Answer 3

1. Morbidity and mortality

2. Overly rapid correction of chronic hyponatraemia can cause serious neurologic defects and death

Question 4

What is isotonic or hypertonic hyponatraemia?

Answer 4

Hyponatraemia with normal or increased osmolality can occur:

1. Solutes other than sodium present in plasma
2. Hyper osmolality produced by xs solutes causes Osmotic shift from ICF to ECF
3. Causes a dilutional decrease in sodium
4. Most commonly seen in hyperglycaemia

Question 5

What is the classification of hyponatraemia?

Answer 5

1. mild - Na 125 - 135mmol/L
2. moderate - Na 115 - 124mmol/L
3. severe - Na < 115 mmol/L

Question 6

What patients are at risk of developing hyponatraemia?

Answer 6

1. Post operative patients
2. Alcoholics
3. Malnourished patients
4. Psychiatric polydipsic patients
5. The elderly caused by chronic disease and certain medication
6. Burns patients

Question 7

How is Hyponatraemia categorised?

Answer 7

1. Hypervolaemic, increased Na, greatly inc H2O
2. Normovolaemic, normal Na, slightly inc H2O
3. Hypovolaemic, greatly reduced Na red H2O
4. Drug induced hyponatraemia

Question 8

What do the symptoms hyponatraemia occur?

Answer 8

1. 130-135mmol/l - asymptomatic
2. <125mmol/l - start to appear
3. < 115mmol/l - symptoms present

Question 9

What are the initial signs and symptoms of hyponatraemia?

Answer 9

Signs and symptoms often non specific:

1. Lethargy, anorexia, agitation, disorientation
2. Seizures and coma
3. Cerebral oedema maybe seen in acute onset of Hyponatraemia

Question 10

What are the features of moderately severe hyponatraemia?

Answer 10

Plasma Na of <120mol/l:

1. Headache, nausea, vomiting
2. Malaise, irritability, depression personality change
3. Cramps, muscle weakness

Question 11

What conditions show Hyponatraemia?

Answer 11

1. Addison’s disease
2. Psychogenic polydipsia
3. Heart failure
4. Liver cirrhosis
5. Adenoma of rectum
6. burns/vomiting
7. diarrhoea
8. hypothyroidism
9. SIADH
10. thiazides