Lithium Flashcards Preview

Psychiatry > Lithium > Flashcards

Flashcards in Lithium Deck (24):
1

Mechanism of action (4)

Unknown
Reduces dopamine release
Increases serotonin release
Reduces secondary intracellular messengers

2

Indications (3)

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

3

Precautions with use (4)

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

4

How does hyponatremia affect lithium use

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

5

When patient has surgery, should they keep taking the lithium

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

6

Effects on pregnancy

Increased CHD
Neurotoxicity
Hypothyroidism

7

Should lithium be used in pregnancy

Avoid in first trimester, use following.
Need to check lithium levels more frequently

8

When should bloods be taken for lithium concentration

12 hours after last dose

9

After starting treatment when do you measure levels

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

10

Once stabilised how frequently are levels checked

Every 3 months

11

When should levels be monitored more frequently

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

12

Counselling a patient using lithium (using ALTHETICS model)

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

Important complications

Renal toxicity
Nephrogenic diabetes insipidus
Hypothyroidism

14

Common causes of lithium toxicity

Overdose
Sodium or fluid loss
Concurrent medical illness

15

Clinical presentation in lithium toxicity

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

16

Is acute or chronic lithium toxicity more common

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

17

Why is acute toxicity less common

Excreted from the kidneys, not a reflection of CNS concentration

18

When does chronic lithium toxicity occur

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

19

When chronic level is associated with severe toxicity

>2mmol/L

20

How does the level in acute differ from chronic

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

21

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

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

22

Key investigations in toxicity

UEC
ECG
Serum lithium

23

Management

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

24

Indications for dialysis in toxicity

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