Chem Path: Sodium and fluid balance

Question 1

What are the 2 receptors ADH acts on and what it does

Answer 1

Acts on V1 to reabsorb water and acts on V2 to vasoconstrict

Question 2

What are the 2 stimuli for ADH relsease

Answer 2

Increased serum osmolality and reduced BP

Question 3

What is the first thing you assess in a hypoNa patient?

Answer 3

Volume status - hyper, eu or hypo volaemic?

Question 4

What is the most reliable clinical sign of hypovolaemia?

Answer 4

Low urine sodium (<20)

Question 5

What are the causes of hypoNa and hypovolaemia?

Answer 5

Renal problems losing salt and water
D and V
Diuretics

Question 6

What are the causes of euvolaemic hypoNa

Answer 6

Hypothyroid, Adrenal insufficiency, SIADH

Question 7

What are the causes of hypervolaemic hypoNa?

Answer 7

Cardiac failure, cirrhosis and nephrotic syndrome

Question 8

How is Cushings diagnosed?

Answer 8

24 hour cortisol. Then do dexamethasone suppression test. If cortisol is suppressed, it is a pituitary problem, if it isnt, its an adrenal problem

Question 9

Why should you not bring Na up rapidly?

Answer 9

Can cause osmotic demyelination syndrome - dysphagia, quadriplegia, dysarthria, seizures, coma and death

Question 10

How do you treat that?

Answer 10

Dextrose and DDAVP

Question 11

How do you treat severe hypoNa

Answer 11

Hypertonic 3% saline, but do not give if no reduced GCS or if not in seizures

Question 12

What is the extent to hoe much you can raise Na?

Answer 12

8-10mmol/L

Question 13

What drugs do you use to treat SIADH

Answer 13

Demeclocycline and tolvaptan

Question 14

What can cause hyperNa

Answer 14

Renal losses, GI loss, sweat loss and DI

Question 15

How do you treat hyperNa

Answer 15

5% dextrose for water deficit. If hypovolaemic, also give normal saline 0.9% for EC fluid defecit, then 5% dextrose

Question 16

What are the effect of DM on Na

Answer 16

Hyperglyaemia can draw out water from the cells, thereby causing hypoNa

Osmotic diuresis can lead to loss of water and hyperNa

Question 17

Summarise: Hypovolaemic hypoNa causes

Answer 17

Urine Na > 30 - Aldosterone defeciency,

Urine Na < 30 - D&V, pancreatitis

Question 18

Summarise: Euvolaemic hypoNa causes

Answer 18

Urine Na > 30 - SIADH, Glucocorticoid def

Urine Na < 30 - Hypothyroid, water overload

Question 19

Summarise: Hypervolaemic hypoNa causes

Answer 19

Urine Na > 30 - renal failure

Urine Na < 30 - HF, cirrhosis, nephrotic syndrome

Question 20

What are the clinical features of DI

Answer 20

Polydipsia, polyuria, hyperNa, lethargy, thirst, irritability, confusion, coma, fits, euvolaemia

Question 21

What will the ADH be in cranial DI

Answer 21

Low or none

Question 22

How do you diagnose?

Answer 22

Water deprivation test. Urine will only concentrate after giving desmopressin