Renal - Sodium imbalances

Question 1

Name 2 complications in the body that hypernatraemia can cause?

Answer 1

1) Dehydration (2) Vascular shear stress - leading to bleeding and thrombosis

Question 2

Name some symptoms of hypernatraemia?

Answer 2

(1) Thirst (2) Irritability (3) Weakness (4) Confusion (5) Reduced consciousness (6) Seizures (7) Hyperreflexia (8) Coma (9) Spasticity

Question 3

Hypernatraemia can be split into three classifications - name these

Answer 3

Hypovolaemic, euvolaemic and hyperkalaemia hypernatraemia

Question 4

What are some causes of hypovolaemic hypernatraemia?

Answer 4

Osmotic diuresis - NG feed

Non-renal free water losses such as burns, sweating, diarrhoea and fistulas

Question 5

Name some reasons for euvolaemic hypernatraemia?

Answer 5

Diabetes insipidus

Hypodipsia

Question 6

Name some reasons for hypervolaemic hypernatraemia?

Answer 6

Primary hyperaldosteronism

Cushing’s syndrome

Hypertonic dialysis

Question 7

What is diabetes insipidus?

Answer 7

A disease where the secretion of (Cranial DI) or response to (nephrogenic DI) ADH is impaired therefore leading to polydipsia and polyuria and as a result often patients will be hypernatraemic.

Question 8

Name some clinical signs of hyponatraemia?

Answer 8

Decreased perception

Gait disturbance

Nausea

Reversible ataxia

Headache

Confusion

Seizures

Coma

Question 9

Name the main cause of hyponatraemia?

Answer 9

Pseudo hyponatraemia - occurs due to hyperlipidaemias, myeloma, hyperglycaemia, uraemia, etc.

Question 10

What investigations would you carry out in a patient with sodium imbalances?

Answer 10

Plasma osmolality

U+E’s = hypokalaemia potentiates ADH release 
Magnesium = hypomagnesaemia potentiates ADH release

Urine sodium = if <20 then non-renal salt losses (burns, sweating, diarrhoea, fistulas), if >40 then SIADH

Question 11

Name 2 causes of hypovolaemic hyponatraemia?

Answer 11

Renal losses (Urine Na >20) - eg. Diuretics, recovering ATN, Addison’s disease

Non renal losses (Urine Na <20) - Diarrhoea, vomiting, sweating, third space losses (pancreatitis, burns, bowel obstruction)

Question 12

What is SIADH?

Answer 12

Secretion of inappropriate ADH which leads to diuresis. This causes low serum osmolality (because water is retained). Urine osmolality would be high (>100).

Question 13

How do you manage SIADH?

Answer 13

Fluid restrict (<800ml/day)

Give PO NaCl to avoid dilutional hyponatraemia

MAY GIVE FUROSEMIDE IF REQUIRED

Question 14

What is tolvaptan and when can it be given?

Answer 14

Tolvaptan is an ADH receptor antagonist and can be given to manage patients with SIADH, and can be indicated in heart failure patients.

Question 15

What medical conditions can cause hypervolaemic hyponatraemia?

Answer 15

Congestive cardiac failure, liver cirrhosis and nephrotic syndrome.

Question 16

What is the risk of correcting hyponatraemia too quickly???

At what rate should it be corrected?

Answer 16

If you correct hyponatraemia too quickly this can cause central pontine myelinosis.

You should aim to correct at <12mmol/L/day

Question 17

Management of patients with acute hyponatraemia?

Answer 17

3% hypertonic saline IV blouses +/- furosemide

Question 18

Name some causes of acute hyponatraemia??

Answer 18

Iatrogenic

Polydipsia

Colonoscopy prep

Ecstasy

Question 19

How do you manage chronic hyponatraemia?

Answer 19

If chronic (>48 hours) and symptomatic -

Having seizures? Hypertonic saline

Asymptomatic? Isotonic saline and furosemide