Lithium toxicity

Question 1

Lithium uses

Answer 1

• Long-term (prophylactic) mood stabiliser in bipolar affective disorder
o Minimises risk of relapse

Question 2

What is the issue with it? How is this risk reduced

Answer 2

It has a narrow therapeutic window

Blood samples for serum lithium 12 hours post first dose and then weekly until therapeutic serum level is reached (0.5-1.0mmol/L) + stable for 4 weeks → once stable every 3mths (w/ eGFR regularly)

Question 3

What needs to be checked before starting lithium

Answer 3

o	ECG
o	Pregnancy test
o	TFTs
o	U+Es
o	eGFR (renal function)
o	BMI

Question 4

Side effects from lithium

Answer 4

L - Leucocytosis
I - Insipidus (Diabetic) - polydipsia + polyuria due to lithium’s ADH antagonism
T - Tremor, Teratogenicity (esp in first trimester)
H - Hypothyroidism
I - Increased weight gain
U - Vomiting, nausea, GI disturbance
M - Miscellaneous - ECG changes, acne, memory problems

Rx - lower dose

Question 5

What is lithium toxicity

Answer 5

An emergency that can result in coma and death.

Question 6

What serum levels of lithium are required to result in toxicity ?

Answer 6

• Serum lithium >1.5mmol/L → signs/symptoms of toxicity

* Serum lithium >2.0mmol/L → severe toxicity

Question 7

What are the early signs and symptoms of lithium toxicity?

Answer 7

N+V, marked/coarse tremor*, dehydration, lethargy, ataxia, muscle weakness, apathy

*coarse tremor in toxicity (fine tremor as a SE)

Question 8

If lithium levels rise further what symptoms can you get

Answer 8

restlessness, muscle fasciculations, hypertonia → ataxia, dysarthria, drowsy, confused → hypotension + cardiac arrhythmias → circulatory collapse → coma + death

Question 9

Treatment for lithium toxicity

Answer 9

o Dose adjustment → severe toxicity: IV isotonic saline (if renal failure: haemodialysis)

Question 10

Prevention of lithium toxicity

Answer 10

Educate pt → maintain hydration + to look out for clinical features

Question 11

What malformations can lithium cause in pregnancy?

Answer 11

It’s teratogenic

Can cause cardiac probs - Ebstein’s anomaly (congenital malformation of tricuspid valve) if used in 1st trimester

Question 12

Can lithium be used at all in pregnancy?

Answer 12

o Balance needs to be struck between risks of teratogenicity and risk of relapse of BPAD
o Taper down dosage
o Counselling