Lesson 1 of 5 · 28 min

Lithium: The Gold-Standard Mood Stabilizer

Learning objectives

Describe lithium's renal handling and narrow therapeutic index
Identify drug interactions that raise lithium levels
Plan baseline and ongoing monitoring

Lithium is a monovalent cation used for acute mania and maintenance treatment of bipolar I disorder, with evidence for reducing suicide risk. It is not metabolized by the liver — it is excreted almost entirely by the kidneys, which is why renal function and sodium/fluid balance drive its levels.

Typical maintenance serum targets are commonly cited around 0.6–1.0 mEq/L, drawn as a trough about 12 hours after the last dose. Levels above roughly 1.5 mEq/L raise concern for toxicity; always follow current prescribing references and local protocols.

Because the kidney treats lithium like sodium, anything that causes sodium loss or dehydration (vomiting, diarrhea, heavy sweating, low-salt diets) increases lithium reabsorption and raises levels.

Key points

Renally cleared — no hepatic metabolism
Baseline: BMP/creatinine, TSH, pregnancy test, ECG if indicated
Long-term: hypothyroidism, nephrogenic diabetes insipidus, CKD risk

Exam pearls

◆ NSAIDs, ACE inhibitors, ARBs and thiazides RAISE lithium levels
◆ Coarse tremor, confusion, ataxia, vomiting = suspect toxicity
◆ Fine tremor is common and not by itself toxicity

Educational content for exam preparation; verify dosing and monitoring with current prescribing information. References: [APA 7 placeholder — to be supplied by author].

Lesson check

Question 1 · lithium

A patient stable on lithium is started on ibuprofen for back pain. Which outcome is MOST likely?

Question 2 · lithium

Which finding in a patient on lithium MOST suggests toxicity?

Question 3 · lithium

Which laboratory test is MOST important to monitor long-term for an endocrine adverse effect of lithium?