Ricin: Diagnosis & Laboratory Guidance for Clinicians

Laboratory Diagnosis

Nonspecific laboratory findings in ricin poisoning:
- Metabolic acidosis
- Increased liver function tests
- Increased renal function tests
- Hematuria
- Leukocytosis (two- to five-fold higher than normal value).
The presence of leukocytosis and/or abnormal liver and renal function tests may suggest ricin-associated illness in the correct clinical context but are not very specific.
There are no specific clinically validated assays for detection of ricin that can be performed by the hospital/healthcare facility clinical laboratory.
No methods are available for the detection of ricin in biologic fluids.
Tests for ricinine, an alkaloidal component of the castor bean plant have been developed.
The potential uses of tests for either ricin or ricinine in human biological samples would be primarily for purposes of confirming exposure or assessing the prevalence of exposure rather than diagnostic use.
Testing for ricin in environmental samples most likely will not be immediately available to assist in clinical decision making.
Environmental testing may document the potential for exposure or affirm the exposure circumstances.
Laboratory criterion for diagnosis include detection of ricin in environmental samples.
Laboratory Testing
- Tests performed on ricin-suspicious samples include:
  - Time-resolved fluorescence immunoassay: antibody binds to ricin
  - Polymerase chain reaction: locates and makes copies of parts of the DNA contained in the castor bean plant. The search specifically identifies the DNA of the gene that produces the ricin protein.

Laboratory Guidance

Testing for ricin
- Certain locations around the U.S., such as government and U.S. Postal Service offices use sensors to test for traces of threatening agents such as ricin.
- When a sensor signals positive for detection of ricin, or when other indications suggest that ricin is present, an environmental sample or the suspicious substance is referred to a Laboratory Response Network (LRN) reference public health or partner laboratory that can perform testing for ricin.
- If a healthcare facility has a suspicious substance/environmental sample that requires testing for ricin:
  - Contact the state public health laboratory director.
  - The state public health laboratory director or designee will coordinate transfer of sample(s) to an appropriate LRN laboratory.
  - The healthcare facility’s laboratory is responsible for shipping the substance/sample to the appropriate LRN laboratory.
If a sample tests positive for ricin at the LRN laboratory, the sample may be sent to CDC for additional testing, defining, archiving, or storage.
Test Selection
- Perform laboratory tests for patient management according to healthcare facility protocols.
  - Laboratory tests may include serum electrolyte panel, arterial blood gases, liver function tests, renal function tests, urine testing for evidence of hematuria, and white blood count.
Urine Specimen Collection
- Collect specimens for patient management according to healthcare facility protocols.
- Consult with clinical laboratory and state public health laboratory regarding collection of environmental sample/suspicious substance for ricin testing by LRN reference laboratory.
Specimen Handling
- Start chain of custody documentation.
- Follow guidelines from healthcare facility clinical laboratory and state public health laboratory about chain-of-custody issues, packaging and shipping.
- Guidance for packaging and shipping specimens is found at: Shipping Instructions for Specimens Collected from People Potentially Exposed to Chemical Terrorism Agents
Precautions
- Avoid any activity that places persons at risk for exposure, especially activities that might create aerosols or droplet dispersal.
- Follow laboratory safety practices to prevent exposure.
- Decontaminate laboratory benches after each use and dispose of supplies and equipment in proper receptacles.
- Avoid touching mucosal surfaces with gloved or ungloved hands and never eat or drink in the laboratory.
- Remove gloves before leaving the laboratory, dispose of them in a biohazard container, wash hands, and remove laboratory coat.
Other Tests
- Perform other tests for patient management according to healthcare facility protocols.
- Inhalation: Perform chest x-ray to assess for pulmonary edema when respiratory symptoms present.
Sentinel and Reference Laboratory Information
- The American Society for Microbiology has agreed to take the lead in development and dissemination of sentinel (e.g., hospital-based, clinical institutions, and commercial diagnostics laboratories) laboratory information.
- Information for reference laboratories are available on the Laboratory Response Network secure Website [for questions: e-mail lrn@cdc.gov; toll free HelpDesk at 1-866-LRN-LABS (1-866-576-5227).