Actin is a protein found in smooth muscles and other tissues; actin (smooth muscle) antibody (ASMA) is associated with liver and bile duct autoimmune diseases. The immune response itself is believed to be responsible for the disease process.
Sera from patients with autoimmune chronic active hepatitis (CAH) contain antibodies to smooth muscle antigens that are detectable by IFA on tissues that contain smooth muscle, such as mouse stomach. The antibodies are predominantly IgG. This measurement differentiates CAH and PBC from other liver diseases in which ASMAs are seldom present (e.g., SLE). See Table 8.11.
Collect a 7-mL blood serum sample in a red-topped tube. Observe standard precautions. This amount is sufficient for both ASMA and antimitochondrial antibody (AMA) testing.
Label the specimen with the patient’s name, date, and test(s) ordered and place in a biohazard bag for transport to the laboratory.
ASMAs are found in CAH, a progressive disease of unknown etiology found predominantly in young women. It has factors characteristic of both acute and chronic hepatitis (80% of patients). If this disease is associated with a positive ANA test, the disease is often called lupoid hepatitis.
Antibody titers between 80 and 320 occur commonly in patients with CAH.
Pretest Patient Care
Explain test purpose and procedure.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan if needed. Detection of ASMA by immunofluorescence assists in determining the presence of CAH and need for therapy when used in conjunction with other laboratory tests such as those used to evaluate liver enzymes, ANAs, and IgG levels. All of these are elevated in most patients with CAH.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.