Newcastle Laboratories

Lithium, serum

Clinical Background:

Monitoring serum lithium concentrations is an important part of treatment in patients with acute mania. However, accurate prediction of dosage is difficult as the drug’s toxic/therapeutic ratio is ...

Monitoring serum lithium concentrations is an important part of treatment in patients with acute mania. However, accurate prediction of dosage is difficult as the drug’s toxic/therapeutic ratio is very low and it’s pharmacokinetics vary from person to person.
Lithium is used for prophylaxis in patients with recurrent unipolar and bipolar affective illnesses. However, in such patients it may be difficult to find a dosage that is effective and does not cause adverse effects.

Because serum lithium concentrations vary quite widely between doses it is important that they are measured at a standard time. This measurement is called the standard serum lithium concentration, and has been standardised at twelve hours after the previous dose.

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Test Details

  • Discipline:

    Biochemistry

    Biochemistry

  • Specimen Container Adult:

    Serum-SST

    Serum-SST

  • Specimen Container Paediatric:

    Serum-Plain tube

    Serum-Plain tube

  • Minimum Volume Adult:

    1 mL blood

    1 mL blood

  • Minimum Volume Paediatric:

    0.5 mL blood

    0.5 mL blood

  • Special Requirement:

    Do not use lithium heparin tubes.
    Standard sampling time of 12h post dose is recommended.

    Do not use lithium heparin tubes.
    Standard sampling time of 12h post dose is recommended.

  • Sample Stability:

    Before separation: day of collection


    After separation

    at +15° to +25°C: 1 day
    at +2° to +8°C: 7 days
    at -20°C: Not stated

    Before separation: day of collection


    After separation

    at +15° to +25°C: 1 day
    at +2° to +8°C: 7 days
    at -20°C: Not stated

  • Interpretation:

    Major long term effects encountered by patients with serum concentrations in the therapeutic range include thirst, polyuria, tremor, weight gain, diarrhea and hypothyroidism.
    When lithium levels e...

    Major long term effects encountered by patients with serum concentrations in the therapeutic range include thirst, polyuria, tremor, weight gain, diarrhea and hypothyroidism.
    When lithium levels exceed the therapeutic range there may be some renal impairment, gastrointestinal symptoms, neuromuscular disorders, central nervous system effects and cardiac arrhythmias.
    Early signs of toxicity are drowsiness, slurred speech, and coarse tremors; this is followed by nausea, vomiting, diarrhea, sluggishness, thirst, polyuria, and eventually stupor and convulsions.

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  • Reference Ranges:

    Therapeutic range (12 hours post dose): 0.4 to 1.0 mmol/l
    Elderly patients may experience toxicity within the upper limits of this range.

    Therapeutic range (12 hours post dose): 0.4 to 1.0 mmol/l
    Elderly patients may experience toxicity within the upper limits of this range.

  • Routine Contact Name:

    Duty Biochemist

  • Routine Telephone:

    Freeman: 0191 244 8889
    RVI: 0191 282 9719

    Freeman: 0191 244 8889
    RVI: 0191 282 9719

  • Routine Email:

Availability:

Available at all times
Analysed at the RVI

Turn Around:

- Urgent sample: 1 hour

Done on a single site. Where urgent samples come from a different site, they will be done within 3 hours.

- Routine sample: 24 hours

Send To:

Department of Blood Sciences

Freeman Hospital
Freeman Road
Newcastle upon Tyne
NE7 7DN

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