Lithium Flashcards Preview

Psychiatry > Lithium > Flashcards

Flashcards in Lithium Deck (24)
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1
Q

Mechanism of action (4)

A

Unknown
Reduces dopamine release
Increases serotonin release
Reduces secondary intracellular messengers

2
Q

Indications (3)

A

Prevent manic/depressive episodes in bipolar
Treat acute mania
Schizoaffective disorder and chronic schizophrenia

3
Q

Precautions with use (4)

A
Hyponatremia->+risk of toxicity
Hypothyroidism
Psoriasis- exacerbate/precipitate
Drugs which risk serotonin toxicity
Renal function- including with drugs that affect renal clearance (NSAIDS)
4
Q

How does hyponatremia affect lithium use

A

Low water and salt= +reabsorption of lithium in proximal tubule of kidney->risk of toxicity

5
Q

When patient has surgery, should they keep taking the lithium

A

Consider interrupting treatment briefly as fasting and changes in fluid intake can alter serum levels

6
Q

Effects on pregnancy

A

Increased CHD
Neurotoxicity
Hypothyroidism

7
Q

Should lithium be used in pregnancy

A

Avoid in first trimester, use following.

Need to check lithium levels more frequently

8
Q

When should bloods be taken for lithium concentration

A

12 hours after last dose

9
Q

After starting treatment when do you measure levels

A

5-7 days later, and after every dose change until stabilised

10
Q

Once stabilised how frequently are levels checked

A

Every 3 months

11
Q

When should levels be monitored more frequently

A
During illness
Manic or depressive phases
Changes in diet or temp
Pregnancy
Concomittant medication
12
Q

Counselling a patient using lithium (using ALTHETICS model)

A

Mood stabiliser. Exact mechanism unknown. Thought to enter cells and interfere with neurotransmitter release and second messenger
Take once or twice daily in tablet/capsulesyrup form
Long term treatment
4-6 months before full effect.
Prior to starting need to test- FBC, LFTs, UEC, BUN/Cr, TSH, pregnancy, ECG. Test lithium level after 5-7 days, then retest every week until stabilised, then every 3 months
SE: Leukocytosis, Insipidus, Tremore/teratogenic, Hypothyroid, Increase weight, Vomiting, nausea, ECG changes
Toxicity: GI (severe NVD), Cerebellar- ataxia, slurred speech, lack of coordination, Cerebral- drowsy, myoclonus, choreiform, UMN, seizures, delirium, coma, death
Complications- renal toxicity, nephrogenic diabetes insipidus, hypothyroidism
Contraindications- 1st trimester, breast feeding, Cardiac/renal/addisons, low sodium diets, untreated hypothyroidism

13
Q

Important complications

A

Renal toxicity
Nephrogenic diabetes insipidus
Hypothyroidism

14
Q

Common causes of lithium toxicity

A

Overdose
Sodium or fluid loss
Concurrent medical illness

15
Q

Clinical presentation in lithium toxicity

A

Severe NVD
Ataxia, poor coordination, slurred speech
Drowsiness, myoclonus, choreiform/parkinsonism, UMN, seizures, delirium, coma
ECG changes

16
Q

Is acute or chronic lithium toxicity more common

A

Chronic more common, acute ingestion= large excretion from the kidney

17
Q

Why is acute toxicity less common

A

Excreted from the kidneys, not a reflection of CNS concentration

18
Q

When does chronic lithium toxicity occur

A

Change in dose
Addition of other medications interfering (NSAIDs)
Reduced elimination- kidney dysfunction

19
Q

When chronic level is associated with severe toxicity

A

> 2mmol/L

20
Q

How does the level in acute differ from chronic

A

Levels in acute can reach >5mmol/L without causing severe toxicity

21
Q

What are the key factors in chronic lithium toxicity (6)

A
Age >50
Fluid status
Impaired kidney function
Hypothyroidism
Diabetes insipidus
Drug interactions
22
Q

Key investigations in toxicity

A

UEC
ECG
Serum lithium

23
Q

Management

A

Fluid resuscitation
Measure UEC, ECG, levels
Consider dialysis if indicated

24
Q

Indications for dialysis in toxicity

A

Lithium >2.5mmol/L in chronic
Persistent clinical effects
Lithium concentration >1.5 and associated with persistent clinical effects, failure to respond to fluids, impaired kidney function