Psychiatric_Lithium

Question 1

mechanism of action and excretion?

Answer 1

absorbed by the gut
renally excreted
hepatic metabolism - minimal

(ref: NPS safe + effective use lithium)

Question 2

Therapeutic levels

Answer 2

0. 4-0.8mmol/L (if pt more prone to depressive episodes)

0. 6-0.8mmol/L (if pt more prone to manic episodes)

Question 3

Toxic level

Answer 3

> 1.5mmol/L

Question 4

1. initial side effects

2. long term side effects

Answer 4

1. nausea, vomiting, diarrhoea
   fatigue, headache,
   thirst, polyuria
2. > 10% increased risk of diabetes insipidus
   6x more likely to get hypothyroidism
   hyperthyroidism –> increasing calcium
   (ref: NPS safe + effective use lithium)
   weight gain

(ref: NPS safe + effective use lithium)

Question 5

acute or chronic toxicity
1/ clinical features

–> note acute toxicity is usually benign if adequate hydration is maintained

Answer 5

1/
CNS: confusion -> coma, cerebella symptoms, seizure, basal ganglia symptoms (choreiform movements, Parkinson-like)
GIT: nausea, vomiting, bloating
CVS: syncope
RENAL: polyuria, polydipsia, renal insufficiency
NEUROMUSCULAR: peripheral neuropathy, myopathy
ENDOCRINE: hypothermia, hyperthermia

Question 6

Chronic lithium poisoning (has an insidious onset)
1/ causes
2/ treatment

Answer 6

1/ Interaction with drugs that effect renal clearance of lithium e.g. NSAIDS, Diuretics, ACE, Alpha2 receptor blockers
Reduced fluid intake
Reduce sodium chloride intake (e.g. vegetarian diet)
Fluid loss e.g. vomiting, diarrhoea, sweating
CKD
Overdose
Infection

2/ fluids
Dialysis
Recovery can take weeks to days
(ref etg)