The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Environmental Medicine: Integrating a Missing Element into Medical Education
Laboratory Tests
❑ In the evaluation of vinyl chloride-exposed patients, it is important to exclude other etiologies for liver disease.
Short of liver biopsy, there are no definitive clinical clues to distinguish hepatic injury due to vinyl chloride from that of other etiologies such as viral hepatitis infection and ethanol toxicity. (Vitamin A overload, hemochromotosis, and carbon tetrachloride exposure have been reported to cause liver disease only rarely.) Biliary cirrhosis, cholelithiasis, and metastatic cancer should also be considered in the differential diagnosis of liver injury.
Laboratory tests can be used to evaluate patient health, confirm vinyl chloride exposure, and exclude other etiologies such as hepatitis virus. Tests that may be helpful are listed below. Since the histologic appearance of vinyl chloride-induced liver injury is distinct from that due to other agents, biopsy may be the best method to diagnose liver disease caused by this chemical.
Screening Tests
Urinary coproporphyrin and total urinary porphyrins
Liver enzymes
Liver function tests (see below)
Serum bilirubin
CBC with peripheral smear
BUN and creatinine
Urinalysis
Hepatitis serology
Specialized Tests
Vinyl chloride in breath or urine, if exposure is recent
Urinary thiodiglycolic acid, if exposure is recent
Direct Biologic Indicators
❑ There is no reliable direct indicator for vinyl chloride exposure at low levels.
No reliable direct method exists for biologically monitoring exposure to low levels of vinyl chloride. Attempts have been made to correlate vinyl chloride exposure with urinary output of thiodiglycolic acid, a major urinary metabolite that peaks approximately 20 hours after exposure. Because of wide individual variations in excretion patterns, however, urinary thiodiglycolic acid is not reliable when exposure to vinyl chloride occurs at concentrations less than 5 ppm nor several days after exposure. Likewise, at air concentrations less than 5 ppm, no correlation has been found between the amount of vinyl chloride in breath or urine samples and the concentration in inspired air.
Items in cart [0]
