lithium_flashcards

Question 1

What is lithium commonly used for?

Answer 1

Prophylactically in bipolar disorder and as an adjunct in refractory depression

Question 2

What is the therapeutic range for lithium?

Answer 2

0.4-1.0 mmol/L

Question 3

What is the plasma half-life of lithium and how is it excreted?

Answer 3

Long plasma half-life, excreted primarily by the kidneys

Question 4

What are two theories about the mechanism of action of lithium?

Answer 4

Interferes with inositol triphosphate formation; interferes with cAMP formation

Question 5

What are some common adverse effects of lithium?

Answer 5

Nausea/vomiting, diarrhoea, fine tremor, nephrotoxicity, thyroid enlargement, ECG changes, weight gain, idiopathic intracranial hypertension, leucocytosis, hyperparathyroidism and hypercalcaemia

Question 6

How does lithium affect the kidneys?

Answer 6

Causes nephrotoxicity, polyuria, secondary to nephrogenic diabetes insipidus

Question 7

How does lithium affect the thyroid?

Answer 7

Thyroid enlargement, may lead to hypothyroidism

Question 8

What are some ECG changes associated with lithium?

Answer 8

T wave flattening/inversion

Question 9

How does lithium affect weight?

Answer 9

Weight gain

Question 10

What rare condition related to intracranial pressure can lithium cause?

Answer 10

Idiopathic intracranial hypertension

Question 11

What blood condition can lithium cause?

Answer 11

Leucocytosis

Question 12

How does lithium affect calcium levels?

Answer 12

Hyperparathyroidism and resultant hypercalcaemia

Question 13

When should lithium levels be checked after starting or changing the dose?

Answer 13

Weekly and after each dose change until concentrations are stable

Question 14

How often should lithium blood levels be checked once stable?

Answer 14

Every 3 months

Question 15

How often should thyroid and renal function be checked in patients on lithium?

Answer 15

Every 6 months

Question 16

What should patients on lithium be provided with?

Answer 16

An information booklet, alert card and record book

Question 17

summarise lithium

Answer 17

Lithium

Lithium is mood stabilising drug used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression. It has a very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys.

Mechanism of action - not fully understood, two theories:
interferes with inositol triphosphate formation
interferes with cAMP formation

Adverse effects
nausea/vomiting, diarrhoea
fine tremor
nephrotoxicity: polyuria, secondary to nephrogenic diabetes insipidus
thyroid enlargement, may lead to hypothyroidism
ECG: T wave flattening/inversion
weight gain
idiopathic intracranial hypertension
leucocytosis
hyperparathyroidism and resultant hypercalcaemia

Monitoring of patients on lithium therapy
inadequate monitoring of patients taking lithium is common - NICE and the National Patient Safety Agency (NPSA) have issued guidance to try and address this. As a result it is often an exam hot topic
when checking lithium levels, the sample should be taken 12 hours post-dose
after starting lithium levels should be performed weekly and after each dose change until concentrations are stable
once established, lithium blood level should ‘normally’ be checked every 3 months
after a change in dose, lithium levels should be taken a week later and weekly until the levels are stable.
thyroid and renal function should be checked every 6 months
patients should be issued with an information booklet, alert card and record book

Question 18

A 48-year-old woman is reviewed in the clinic. She was recently seen by the psychiatrist and it was recommended that her lithium dose was increased for better symptom control. Her renal function is stable and so you prescribe the increased dose of lithium that is recommended.

When would it be most appropriate to re-check her levels?

In 1 month
In 1 week
In 3 days
In 3 months
In 6 months

Answer 18

After a change in dose, lithium levels should be taken a week later and weekly until the levels are stable
Important for meLess important
Lithium monitoring should be performed weekly after initiation and after each dose change until concentrations are stable. In this case, with an increased lithium dose, the levels should be checked again in 1 week. It is usually checked 12 hours after the dose is taken.

One month would be too long to wait after a dose adjustment.

Three days would be too soon to assess lithium levels.

Once lithium levels are stable they can be checked in 3 months’ time, and then every three months for the first year, but they need to be stable before this occurs.

The BNF suggests that if lithium levels remain stable after a year then lithium testing can go to every 6 months in low-risk patients. NICE guidance suggests that 3 monthly testing continues indefinitely. In addition thyroid function tests should be monitored 6 monthly on patients on lithium.