Serum Levels of Alpha-1 Antitrypsin

 

molecular weight for alpha-1 antitrypsin: 54,000 daltons (some references give 52,000)

 

1 mg/dL = 0.185 µmole per liter

 

Note: Standards used in some commercial assays may not be highly purified. Therefore different assays may give different results for the same sample.

 

Normal Phenotype: MM

Percent of Normal Serum Levels	Phenotype
100%	MM
50 to 100%	MZ, SS, MS, M-null
25 to 49%	SZ
5 to 25%	ZZ or Z-null
<1%	null-null

 

where:

• The abbreviation PI = proteinase inhibitor.

 

The risk of emphysema increases significantly when the serum level is < 11 µM (< 60 mg/dL; ATS Table 3 page 825).

 

Conditions associated with an elevation in serum levels:

(1) acute phase reaction

 

Conditions associated with a decrease in serum levels:

(1) neonatal respiratory distress syndrome

(2) pancreatitis

(3) liver disease

(4) nephrotic syndrome