C1 esterase inhibitor (C1-Inh) is a serine proteinase inhibitor that inactivates C1 esterase as well as other enzymes (including plasmin, kallikrein, coagulation factor 12a).


Molecular weight: 105,000 daltons


1 U of activity is the activity in 1 mL of plasma.


The normal range for plasma is 18 to 40 mg/dL (0.18 to 0.40 mg/mL). A typical plasma concentration is 0.24 mg/mL (will be used as definition of 1 U).


1 mg is equivalent to 9.52 nmol


1 mg/mL is equivalent to 9.52 µmol/L


1 µmol/L = 0.105 mg/mL


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