Lithium

Question 1

What is lithium most commonly used for?

Answer 1

It is a mood stabilising drug that is used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression.

Question 2

What are the proposed mechanisms of action for lithium in mood-stabilisation?

Answer 2

Interferes with inositol triphosphate formation

Interferes with cAMP formation

Question 3

How is lithium excreted?

Answer 3

Via the kidneys

Question 4

What is therapeutic window for lithium?

Answer 4

Very narrow, hence why it is such a toxic drug that needs such close monitoring. Range is 0.4 - 1.2 mmol/L. It also has a very long plasma half-life.
>1.5 is toxic

Question 5

What can affect lithium clearance from the body and lead to a build up of lithium to toxic levels?

Answer 5

Renal impairment

Sodium depletion - the kidney will hold onto lithium in place of sodium

Diuretics especially bendroflumethiazide

NSAIDs

ACE-inhibitors

Antipsychotics can synergistically increase lithium induced neurotoxicity

Question 6

What are the side effects of lithium?

Answer 6

VANISH LITH

Vertigo
Ataxia
Nystagmus
Intention tremor (fine)
Hypothyroidism

Leukocytosis
Impaired renal function
T-wave inversion ECG and Teratogenicity
Heaviness (weight gain)

Question 7

What are the complications of lithium therapy?

Answer 7

Nephrogenic diabetes insipidus

Thyroid enlargement, may lead to hypothyroidism

Precipitates skin problems eg psoriasis

Leucocytosis

Teratogenicity - Ebstein’s anomaly

Exacerbate myasthenia gravis

Question 8

What are the clinical features of lithium toxicity?

Answer 8

Polydipsia

Polyuria

Coarse tremor

Hyperreflexia

Acute confusion

Seizure

Coma

Question 9

What are the ECG changes associated with lithium toxicity?

Answer 9

T-wave flattening or inversion

Question 10

How do we manage someone with mild-moderate lithium toxicity?

Answer 10

May respond to fluid resuscitation

Question 11

How do we manage someone with severe lithium toxicity?

Answer 11

Haemodialysis

Sodium bicarbonate is sometimes used but there is limited evidence to support this. By increasing the alkalinity of the urine it promotes lithium excretion.

Question 12

In which patients in lithium therapy contraindicated?

Answer 12

Breast feeding mothers

Relative contraindication for those on antipsychotics, NSAIDs, diuretics (bendroflumethiazide) and cardioactive drugs.

Question 13

How are lithium levels monitored and what is the desired range?

Answer 13

Should be checked weekly until stable for 4 weeks and every 3 months thereafter

Levels taken 12 hours post-dose

Range should be 0.4 - 1.0 mmol/L

Patients should be issued with an information booklet, alert card and record book

Question 14

As well as lithium levels, what else should be monitored in a patient on lithium for mood stabilisation?

Answer 14

Thyroid function

Renal function

ECG

Question 15

What monitoring tests are needed for someone starting on lithium as treatment for bipolar affective disorder?

Answer 15

FBC

U+Es

TFTs

Pregnancy test

ECG