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Alpha-1 Antitrypsin Deficiency P002

Document
Last amended 
30 June 2015

Current RMA Instruments:

Reasonable Hypothesis SOP
29 of 2015
Balance of Probabilities SOP 
30 of 2015
Changes from Previous Instruments:

SOP Bulletin 179

ICD Coding:
  • ICD-9-CM Codes: 277.6
  • ICD-10-AM Codes: E88.0

Alpha-1 antitrypsin deficiency means a genetic disorder of plasma protein metabolism, heritable in an autosomal codominant pattern, which is characterised by reduced serum levels of alpha-1 antitrypsin. Common clinical manifestations include emphysema and cirrhosis of the liver.

Is specific diagnostic evidence required to apply the SOP? – Yes.

This diagnosis is based on serum alpha-1 antitrypsin levels, and genetic testing. A specialist opinion from a respiratory physician, gastroenterologist or specialist general physician would be applicable together the relevant imaging and function testing of the liver and lungs. E.g. MRI [magnetic resonance imaging] scan of the abdomen, liver function testing, liver biopsy, CT [computerised axial tomogram] scan of the chest, complex lung function tests.

Are there sub-factors that require specific information? – No.

The only relevant factors are for clinical worsening (inability to obtain appropriate clinical management, and smoking) and it is difficult to ascertain a clinical worsening given the progressive nature of the disorder.  See further notes, below.

Additional diagnoses covered by SOP
  • Nil
  • If emphysema or cirrhosis are present then consider apply the SOPs for those conditions (chronic obstructive airways disease, cirrhosis of the liver)
Unconfirmed diagnosis

If, after applying the above information, you are unable to confirm the diagnosis, you should then seek medical officer advice about further investigation.

Notes on clinical worsening

Natural progression of the disease varies with the phenotype.  Worsening beyond the normal progression of the disease needs to be evident before a clinical worsening factor can be considered.

The only specific treatment currently available is augmentation of the alpha antitrypsin levels intravenously if the serum level is less than 11 mmol/L in a high risk phenotype though the efficacy of this treatment is as yet unclear. Apart from this specific therapy, the treatment is supportive and protective of the liver and the lungs.

Current understanding of the natural history of Alpha-1 antitrypsin deficiency is patchy, with some aspects being reasonably clear and others still murky.  Within the first two decades of life, liver dysfunction is the major threat to the health of affected individuals, and pulmonary dysfunction is not a major concern. Beyond the first two to three decades of life, the natural history of individuals with severe deficiency of AAT is less clear. But available estimates of the yearly decline in FEV1 among smokers range from as low as 42 to as high as 317 mL per year, compared with 44 to 110 mL per year in nonsmokers or ex-smokers.  The prevalence of COPD among subjects with severe AAT deficiency has been estimated to be 75 to 85 percent, with liver disease occurring in 12 to 16 percent.