Lithium Flashcards
Organ lithium is excreted by
Kidneys
Congenital anomaly associated with maternal lithium use during pregnancy
Ebstein’s anomaly
Risk of Ebstein’s anomaly in the general population
1 in 20000
Risk of Ebstein’s anomaly when exposed to lithium in utero
1 in 1000
Structural abnormality in Ebstein’s anomaly
Prolapse of the tricuspid valve into the right ventricle
ECG seen in therapeutic lithium levels
Flat or inverted T waves
Contraindications to lithium use
Addison's disease Brugada syndrome Cardiac rhythm disorders including sick sinus syndrome Significant renal impairment Untreated hypothyroidism Hyponatraemia
Common side effects of lithium treatment at therapeutic levels
Nausea Polyuria/polydipsia Fine tremor Blurred vision Rash Dizziness Decreased appetite Metallic taste Causing and worsening psoriasis
Cause of polyuria and polydipsia in lithium use
ADH insensitivity
Long-term side effects of lithium use
Hypothyroidism or hyperthyroidism
Hypercalcaemia, hyperparathyroidism
Irreversible nephrogenic diabetes insipidus
Reduced eGFR
Features of lithium induced fine tremor
Symmetrical Largely in hands Similar to physiological tremor Typically occurs early in treatment More common in older patients Most apparent with intentional posture
Lithium levels to aim for in general circumstances
0.4-1.0mmol/L
Lithium levels to aim for if diabetes insipidus is a concern
0.4-0.8mmol/L
Cells affected in nephrogenic diabetes insipidus
Principle cells of the collecting duct
First line treatment for lithium induced nephrogenic diabetes insipidus
Amiloride
Treatments for lithium induced nephrogenic diabetes insipidus
Amiloride
Thiazide diuretics
Indomethacin
Desmopressin
Mechanism of action of amiloride in treating lithium associated nephrogenic diabetes insipidus
Blocks Na channels
Lithium cannot use Na channels to gain access to the principle cells of the collecting duct and cannot prevent water reabsorption there
Time lithium levels should be taken
12 hours post dose
Lithium levels to aim for in an acute manic episode
0.8-1.0
Drugs which increase lithium levels
NSAIDs
Thiazide diuretics
ACE inhibitors
Impact of loop diuretics (e.g. furosemide) on lithium levels
Generally no change, can increase
Risk factors for lithium toxicity
Associated drugs Decreased circulating volume e.g. sauna usage Infections Fever Decreased oral intake Renal insufficiency Nephrogenic diabetes insipidus Hyponatraemia
Features of lithium toxicity
Nausea, vomiting, diarrhoea, abdo pain Coarse tremor Confusion Seizures Dystonia Hyperreflexia Nystagmus Ataxia
Scale used to assess the severity of lithium toxicity
AMDISEN rating scale
Features seen at stage 0 lithium toxicity on the AMDISEN scale
No clinical signs or symptoms
Features seen at stage 1 lithium toxicity on the AMDISEN scale
Nausea, vomiting Tremor Hyperreflexia Agitation Weakness Ataxia
Features seen at stage 2 lithium toxicity on the AMDISEN scale
Stupor
Rigidity
Hypertonia
Hypotension
Features seen at stage 3 lithium toxicity on the AMDISEN scale
Myoclonus
Cardiovascular collapse
Seizure
Coma
Baseline tests that must be performed before prescribing lithium
Renal function
ECG
TFTs
FBC
When lithium levels should be checked
Weekly until levels are stable
3-6 monthly once stable
When thyroid and renal function should be checked while on lithium
Every 6 months
Timing of polyuria in patients taking lithium
Often associated with time of peak levels
Cause of chronic renal damage in long term lithium use
Interstitial fibrosis
Lithium level above which haemodialysis may be required
4mmol/L
Most common thyroid effect of lithium use
Benign hypothyroid state
Binding of lithium to serum proteins
Does not bind
Form of lithium available as a liquid
Lithium citrate
Form of lithium available as tablets
Lithium carbonate
Indications for lithium
Treatment and prophylaxis of mania
Treatment and prophylaxis of bipolar disorder
Treatment and prophylaxis of recurrent depression
Treatment and prophylaxis of aggressive or self harming behaviour
Level of binding lithium shows in the blood
Exists unbound
Investigation to confirm lithium toxicity if level is normal
EEG
Use for lithium prior to its being used for psychiatric illness
Gout
Predictor of a poor response to lithium in patients with bipolar disorder
Rapid cycling bipolar disorder
Demographic at highest risk of lithium induced hypothyroidism
Young women
Dosing schedule which can improve lithium induced tremor
Small, more frequent doses
Safety of lithium in the different trimesters of pregnancy
Should be avoided during the first trimester
Safety of lithium while breastfeeding
Should be avoided
Dosing measure which can improve lithium induced tremor
Smaller, more frequent doses
Issue with fluid restriction as a treatment for lithium induced hyponatraemia
Can lead to severe hypernatraemia
