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Toxicity, Heavy Metals: Treatment & Medication
Updated: Nov 5, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Emergency Department Care
- Decontamination
- Removal of the patient from the source of exposure is critical to limiting dose.
- Treatment may include whole-bowel irrigation with polyethylene glycol electrolyte solution if radiographic evidence of retained metal (toys, coins, paint chips) is present.
- Resuscitation: Good supportive care is critical. Ensure airway patency and protection, provide mechanical ventilation where necessary, correct dysrhythmias, replace fluid and electrolytes (significant fluid losses generally occur and require aggressive rehydration), and monitor and treat the sequelae of organ dysfunction.
- Chelation: Chelation is rarely indicated in the emergent setting. A possible exception in lead encephalopathy. Consideration of chelation therapy for patients with suspected or confirmed metal exposures should be made in conjunction with a medical toxicologist or the local poison control center.
- Clinical guidelines on treatment of iron and mercury exposure are available from the American Association of Poison Control Centers.8,9
Consultations
If intentional ingestion or overdose is suspected, place the patient in a closely monitored unit and consult a medical toxicologist and psychiatrist.
- Contact a certified poison control center or medical toxicologist.
- Consult a gastroenterologist if the possibility of corrosive GI effects is present.
Medication
The most important therapeutic maneuver in many cases of metal toxicity is to remove the source of exposure.
Chelation regimens have been shown to enhance elimination of some metals, and thereby decrease the total body burden. See the Table for a list of accepted chelation agents for specific metals.
There is evidence of no benefit with chelation therapy for several metals, and evidence of increased toxicity after chelation of several others (eg, selenium). Therefore, routine chelation of patients with heavy metal exposure cannot be recommended, and the decision to chelate should be made in conjunction with a medical toxicologist or local poison control center.
Chelation agents
These drugs supply sulfhydryl groups for the heavy metals to attach and, subsequently, may be eliminated from the body.
Dimercaprol (British Anti-Lewisite; BAL)
DOC in the treatment of lead, arsenic, and mercury toxicity. Administered via deep IM injection only, q4h, mixed in a peanut oil base. Chelates intracellular and extracellular lead and is excreted in urine and bile. May be given to patients with renal failure.
Adult
Lead toxicity: 75 mg/m2 IM q4h for 5 d; not to exceed 24 mg/kg/d IM
Arsenic toxicity: 3-5 mg/kg IM q4h for 2 d; 3-5 mg/kg IM qid on day 3; then 3-5 mg/kg IM q6-12h for 10 d (or until recovery is complete)
Mercury toxicity: 3-5 mg/kg IM q4h for 2 d; followed by 3-5 mg/kg IM q6h for 2 d; followed by 3-5 mg/kg IM q12h for 7 d
Pediatric
Lead toxicity: Administer as in adults
Arsenic toxicity:
If symptomatic without encephalopathy: 50 mg/m2/d IM
In asymptomatic children with blood lead >45 mcg/dL: 50 mg/m2/d IM Mercury toxicity: Administer as in adults
Toxicity may increase when coadministered with selenium, uranium, iron, or cadmium
Documented hypersensitivity; concurrent iron supplementation therapy; peanut allergy
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
May be nephrotoxic and may cause hypertension; caution with oliguria or G-6-PD deficiency; may induce hemolysis in G-6-PD deficiency
Edetate calcium disodium (Calcium Disodium Versenate)
Second-line for lead toxicity. Most effective when given early in the course of acute poisoning. Chelates only extracellular lead and may induce CNS toxicity if BAL therapy not initiated first. Begin therapy 4 h after BAL is given. Only given IV, and continuous infusion is recommended.
Not recommended with renal failure. Because of potential for renal toxicity, patient should be well hydrated. To prevent hypocalcemia, use only calcium disodium salt of EDTA for chelation in heavy metal toxicity.
Adult
Encephalopathic patient: 1500 mg/m2/d as continuous IV infusion
Symptomatic nonencephalopathic adult may be treated combined with BAL or alone
Pediatric
Encephalopathic patient: 1500 mg/m2/d continuous IV infusion
Symptomatic nonencephalopathic patient: 1000 mg/m2/d continuous IV infusion
Enhances the hypoglycemic effects of insulin in patients with diabetes
Documented hypersensitivity; renal failure
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Patient should be well hydrated; may worsen CNS toxicity if administered before BAL therapy; check renal and hepatic functions and urinalysis prior to and during therapy; monitor for cardiac rhythm changes; patients with lead encephalopathy may develop increased intracranial pressure during therapy; adverse effects include pain and local thrombophlebitis at site of injection, flulike symptoms, histamine like reaction, hypotension, arrhythmias, GI tract upset, paresthesias, elevated LFTs, acute renal failure, renal tubular acidosis, and transient bone marrow suppression
Do not confuse with the similarly named product edetate disodium (Endrate), which is indicated for hypercalcemia and ventricular arrhythmia secondary to digitalis toxicity; each of these 2 products are commonly referred to as EDTA and, as a result, the 2 products are easily mistaken for each other when prescribing, dispensing, and administering; deaths in patients when mistakenly given edetate disodium instead of edetate calcium disodium or when edetate disodium was used for chelation therapy; for more information, see the FDA MedWatch Safety Information
Penicillamine (Cuprimine, Depen)
Metal chelator used in treatment of arsenic poisoning. Forms soluble complexes with metals that are subsequently excreted in urine.
Adult
Arsenic poisoning: 100 mg/kg PO qd; not to exceed 2 g/d divided qid for 5 d
Mercury poisoning: 100 mg/kg PO qd divided qid; not to exceed 1 g/d for 3-10 d
Pediatric
Arsenic poisoning: 100 mg/kg PO qd; not to exceed 1 g/d divided qid for 5 d
Mercury poisoning: Administer as in adults
Increases effects of immunosuppressants, phenylbutazone, and antimalarials; decreases digoxin effects; effects may decrease with coadministration of zinc salts, antacids, and iron
Documented hypersensitivity; renal insufficiency; previous penicillamine-related aplastic anemia
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Thrombocytopenia, agranulocytosis, and aplastic anemia may occur
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References
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Further Reading
Keywords
heavy metal toxicity, heavy metal poisoning, arsenic, lead, mercury, iron, arsenic poisoning, lead poisoning, mercury poisoning, iron poisoning, metal fume fever, MFF, brass founder's ague, zinc shakes, Monday morning fever
