Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
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        Anti-smooth Muscle Antibody test, blood
      
ASMA

Anti-smooth muscle antibody is an auto-antibody which has been said to be found in some liver diseases...generally accepted as a marker of autoimmune hepatitis (AIH). We use the FLUORO-KIT test system with cryostat sections of rat kidney and stomach, and or rat liver as the substrate at a beginning dilution of patient's serum of 1:20. The use of animal tissue avoids interference from HLA and/or blood group Abs that may occur were human substrate used. Incidental Abs may show up in this system such as APCA, ANA, ARA, ABBA, anti-canalicular Ab, anti-liver cell membrane Ab, and anti-ribosomal Ab. At a starting dilution of patient's serum of 1:20, there are many "false positives" for ASMA at this low-titre level. So, "reactive but, by convention, not 'positive'" is <1:40; and "a nonspecific positive titer" is 1:40-1:160. We have documented instances of levels >1:160 that were not AIH...so, liver biopsy findings are crucial to proper total case interpretation. A 1972 paper providing results of community screening for ASMA found positivity in 1.2% of "normal" people under age 40 and in 3.5% of those over 70 years of age3.

Associations with undetectable Ab:

  • normalcy
  • extra-hepatic biliary obstruction1
Associations with elevated levels:

  • autoimmune (chronic active) hepatitis:  always think of AIH and of Wilson's in a young adult; 50-80% of cases1, 70% at >1:1002; our lab considers >1:160 to be "significant serologic evidence, suspicious for autoimmune hepatitis, especially if liver biopsy contains lots of plasma cells".
  • primary biliary cirrhosis (PBC) 0-50% of cases1
    • cryptogenic cirrhosis 0-1% of cases1    
  • viral hepatitis 1-2% of cases1
some of our case examples with elevated ASMA:
case number clinical result/comments
LMC-01-4435 38 y/o BF with LFTs elevated ASMA .1:320 & <1:1280; Bx hepatic sarcoidosis, cirrhosis and mild acute ascending pericholangitis; AMA, ANCA, ANA all neg.
LMC-01-273 39 y/o M with LFTs elevated & COPD ASMA 1:160; ANA, AMA, anti-LKM all neg.; Bx showed central congestion & sclerosis
LMC-02-81 61 y/o F with LFTs elevated & elevated ferritin ASMA 1:80; ANA & AMA neg.; Bx NASH with cirrhosis
LMC-02-713 54 y/o F high LFTs  ASMA 1:160; ANA & AMA neg; IgG 3680: AIH, Bx
LMC-02-747 48 y/o F elev. LFTs ASMA 1:320, ANA 1:1280; AIH, Bx
LMC-02-4640 61 y/o F high LFTs ANA neg; ANCA neg; ASMA 1:320; AMA 1:1280: PBC-AIH overlap, Bx
LMC-02-6428 38 y/0 F elevated LFTs & family Hx cirrhosis ANA 1:80, speckled; AMA, neg; ASMA 1:40; anti-LKM neg; Bx NASH without fibrosis
LMC-02-8257 55 y/o F SOB & elevated LFTs ANA 1:160 homo. & ASMA 1:160; Bx metastatic small cell ca.
LMC-02-7628 50 y/o F elevated ALT, AST, GGTP ANA 1:640 speckled; ASMA 1:80; Bx normal
LMC-03-3790 79 y/o M acute pancreatitis ASMA 1:320 Bx has mild portal reactive "hepatitis"
L07-6555 19 y/o F elevated LFTs ALT 387; ASMA "pos"; Bx has cirrhosis w/ grade III severe chronic hepatitis c/w AIH.

REFERENCES:

  1. A B C's of Interpretive Laboratory Data, 2nd Ed., Seymour Bakerman, MD, PhD, 1984
  2. Lex. Med. Lab. procedure manual and its references as of 7/01
  3. Rochman H, et. al., textbook: Clinical Pathology in the Elderly...,, 1988, 222 pages.
(posted June 2001; latest update 11 August 2007)
 
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