Introduction

All patients are exposed to uranium in food, air, and water as part of their natural environment. Most exposures to naturally occurring uranium do not warrant monitoring or treatment.

If Overexposure is Suspected or Known

The following steps are relevant if a recent uranium overexposure poses a potential health threat.

• Remove the patient from the workplace or community source of overexposure, since renal damage normally reverses after overexposure ends.
• Externally decontaminate patients to reduce further overexposure if they have residue from the exposure on them.

If overexposure is apparent, you can contact the Radiation Emergency Assistance Center/Training Site (REAC/TS) for medical guidance [REACTS 2008].

REAC/TS:

• is available 24 hours a day, 7 day a week to deploy and provide emergency medical services at incidents involving radiation anywhere in the world,
• provides advice and consultation on radiation emergency medicine from its Oak Ridge, TN headquarters or at the scene of an incident, and
• can be contacted for emergency assistance at 1-865-576-1005 (ask for REAC/TS) or the Internet at http://orise.orau.gov/reacts/

Care of patients who have been overexposed to uranium, whether or not they are symptomatic, should include the assessment of renal function to determine if the exposure may have caused renal damage. This may include measurement of uranium excreted in the urine (biomarker of exposure) as well as abnormalities in the clinical urinalyses (biomarkers of effect), as mentioned in the previous section.

Monitoring

Daily urine samples should be collected after large accidental overexposures [Diamond 1989; Howland 1949], and should continue for at least 2 weeks. The collection of 24-hour urine samples whenever possible is recommended. These samples can be used for both assessment of uranium excretion and for clinical urinalysis.

For acute uranium nephrotoxicity, oral dose or infusions of sodium bicarbonate can be administered to maintain alkaline urine [Lincoln and Voelz 1990; MacNider 1916] with frequent monitoring of urine pH. Alkaline urine prevents dissociation of the uranium-bicarbonate complex that protects the renal tubular epithelium from exposure to the reactive uranyl ion. Forcing fluids to increase urinary output is recommended.

Treatment

The use of chelation drugs for acute uranium overexposures is considered a controversial practice in the United States. No human cases of uranium overexposure have been reported as being treated with chelation in the Western world. Soviet research indicates that chelating agents can significantly reduce the risk of acute uranium injury to the kidneys [Ivannikov 1987]. However, chelation must begin within 4 hours of exposure to be effective, and it is most effective if given within a few minutes of the exposure. Some authors have advised against the use of chelation because precipitation of uranium in the kidney may cause additional damage. The avoidance of calcium DTPA for chelation is mentioned, as it can increase bone deposition.

Instructions to Patients

Patients whose exposures are a result of elevated water or food uranium concentrations from home or community sources should, as a matter of general principle, limit exposure by switching to bottled water or another water source known to contain uranium levels within U.S. Environmental Protection Agency limits.

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