Lithium Poisoning Toxicology Case Study.
Pharmacology case study;
History: A 53 year-old-female presents to the emergency department with her
neighbor who is concerned that she has been disoriented for the past
week. The patient is unable to provide any history except to say that she is
having mild cramping abdominal pain. The neighbor relates that the
patient’s entire family was ill the week prior to symptom onset with a
diarrheal illness that lasted for 5 days.
PMH: Hypertension, stage I kidney disease, bipolar disorder, anxiety
Medications: Hydrochlorothiazide, enalaprilat, lithium, clonazepam prn
Physical Examination:
T: 97.9°F HR: 108 bpm RR 14 breaths per minute BP: 125/76 mmHg
General: Disheveled female in no acute distress. Oriented to person only.
HEENT: Pupils equal, round and reactive to light. Mucous membranes tacky.
CV: Tachycardic, regular rhythm. No murmurs.
Pulmonary: Clear to auscultation.
Abdomen: Normal bowel signs. Soft, with mild, diffuse tenderness. No guarding or
rebound.
Neurologic: Cranial nerves II – XII intact. Motor testing is 4/5 diffusely, but symmetric.
Gait examination reveals ataxia. No clonus or hyperreflexia.
ED course: the patient underwent a full laboratory evaluation that showed a creatinine
of 2.1 (baseline 1.4) and a lithium level of 14 mg/dL.
She was admitted for lithium toxicity, which was thought to result from worsening renal dysfunction after an episode of gastroenteritis.
Case Study Questions:
1. Describe common laboratory and physical exam findings in patients with chronic
and acute lithium poisoning.
2. What are indications for hemodialysis in lithium toxicity? Are there different
indications depending on whether the presentation is the result of acute versus
chronic exposure?
Toxicology case study: Lithium poisoning;
1. Chronic lithium exposures can present with systemic symtoms such as lethargy,
muscular weakness, slurred speech, ataxia, tremor, and myoclonic jerks.
Severe intoxication can cause delirium, coma, convulsions, and hyperthermia.
Patients with chronic lithium poisoning can also develop nephrogenic diabetes
insipidus. Lithium levels may be only slightly above normal. Other laboratory
findings can include leukocytosis. The ECG may show T wave flattening or
inversion, QT prolongation, ST depression in lateral leads, and sinus
bradycardia.
Acute lithium exposures commonly present with nausea and vomiting. Systemic
symptoms are delayed for several hours while lithium distributes into tissues
since it can take lithium about 6-8 hours to be completely absorbed. Initial
lithium levels will be high in an acute intoxication and may fall once it is absorbed
into the tissues. Other labs to obtain include electrolytes and renal function
tests.
2. Lithium is excretion is exclusively by the kidneys. Hemodialysis should be used
for patients with severe symptoms such as abnormal mental status and seizures,
for patients who cannot excrete lithium due to renal disease and patients who
cannot tolerate aggressive fluid resucitations (ex. heart failure). Treatment should
be based on clinical presentation and not laboratory values.
