Blood tests on lithium
For people taking lithium for bipolar disorder, depression or another condition, and the people who help them.
7 tests explainedAI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-19
NICE calls lithium the most effective long-term treatment for bipolar disorder, and it comes with regular blood tests. The lithium level itself is checked often at first, then every few months. Kidney function, thyroid and calcium are checked too, because long-term lithium can affect all three. These checks are routine and help keep treatment steady.
The tests that matter most
Most important first. Each one links to its full page, where the note for this group sits near the top.
Lithium
The lithium level shows whether the amount in the blood is in the range your clinician is aiming for. NICE suggests checking it 1 week after starting and after every dose change, weekly until stable, every 3 months in the first year, then every 6 months for most people.
Sources: NICE (2025) and U.S. National Library of Medicine (2025)
- Usual adult range
- 0.6–1.2 mmol/L
eGFR (Creatinine-based)
Long-term lithium is linked to kidney changes, so kidney function is checked before starting and during treatment. NICE suggests eGFR every 6 months, and more frequent lithium checks if eGFR falls over 2 or more tests.
Sources: NICE (2025), U.S. National Library of Medicine (2025) and BJPsych Bulletin (2025)
- Usual adult range
- 60 and above mL/min/1.73 m²
Creatinine
Creatinine is the blood result eGFR is worked out from. The FDA label names creatinine for checking kidney function on lithium, and NICE suggests closer lithium checks if urea and creatinine rise.
Sources: U.S. National Library of Medicine (2025) and NICE (2025)
- Men, 15+
- 0.74–1.35 mg/dL
- Women, 16+
- 0.59–1.04 mg/dL
TSH (Thyroid Stimulating Hormone)
Lithium can slow the thyroid and lead to an underactive thyroid. The FDA label suggests thyroid tests at 3 months and every 6 to 12 months after that, and NICE suggests every 6 months.
Sources: U.S. National Library of Medicine (2025) and NICE (2025)
- Usual adult range
- 0.45–4.5 mIU/L
Calcium, Total
Long-term lithium is linked to overactive parathyroid glands and high calcium. NICE suggests checking calcium every 6 months, and the FDA label asks for regular checks.
Sources: U.S. National Library of Medicine (2025) and NICE (2025)
- 18–59
- 8.7–10.2 mg/dL
- Men, 60+
- 8.6–10.2 mg/dL
Parathyroid Hormone (PTH), Intact
PTH is the hormone from the parathyroid glands that controls calcium. Long-term lithium is linked to a lasting rise in PTH along with high calcium, so PTH is often read alongside a raised calcium.
- Usual adult range
- 18–59 pg/mL
Sodium
Lithium can lower sodium. Losing salt and water, for example from heavy sweating, diarrhea, fever or some water pills, can push lithium levels up.
Sources: U.S. National Library of Medicine (2025) and NICE (2025)
- Usual adult range
- 135–145 mmol/L
Ranges shown are the usual adult ranges labs print. The range on your own report is the one your result is judged against.
Getting results you can compare
- The label for lithium carbonate tablets and capsules says to draw the blood just before the next dose, 12 hours after the last one, when the level is steadiest. The label for extended-release Lithobid says 8 to 12 hours.
Sources: U.S. National Library of Medicine (2025), U.S. National Library of Medicine (2026) and BJPsych Bulletin (2025)
- Other medicines can change lithium levels. The FDA label lists anti-inflammatory pain relievers (NSAIDs), water pills, some blood pressure medicines that act on the renin-angiotensin system, and the antibiotic metronidazole. NICE suggests more frequent checks for people taking medicines that interact with lithium.
Sources: U.S. National Library of Medicine (2025) and NICE (2025)
- Illness with vomiting, diarrhea or fever, and heavy sweating, can change lithium levels. NICE advises seeking medical attention for diarrhea or vomiting and keeping up fluids after sweating.
Sources: NICE (2025) and U.S. National Library of Medicine (2025)
Good to know
- Side effects on the nerves, such as tremor, unsteadiness or tingling, can happen even at usual lithium levels. NICE suggests asking about them at every visit, so how you feel matters as well as the number.
Source: NICE (2025)
- Older people often have lower kidney function and take more medicines, both of which can let lithium build up. NICE suggests checking lithium every 3 months for older people rather than every 6.
Sources: BJPsych Bulletin (2025) and NICE (2025)
Questions you could ask
- What lithium level are we aiming for, and why?
- When are my next lithium, kidney and thyroid tests due?
- How should my blood draw be timed around my lithium dose?
- Which medicines or illnesses should I mention because they can change my lithium level?
Sources
- Bipolar disorder: assessment and management (CG185), NICE (2025)
- Lithium carbonate tablets and capsules: prescribing information, U.S. National Library of Medicine (2025)
- Lithobid (lithium carbonate) extended-release tablets: prescribing information, U.S. National Library of Medicine (2026)
- The importance of safe lithium plasma monitoring in older people, BJPsych Bulletin (2025)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-19. How we build and check these pages.
Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.