Serum ACE

Purpose:
ACE (angiotensin I converting enzyme) is as a key component of the renin-angiotensin system, whose main function is to process angiotensin I to angiotensin II and degrade bradykinin. The renin-angiotensin system is responsible for the maintenance of normal blood pressure and electrolyte balance. ACE is expressed in endothelial and epithelial cells and is found in arterioles, muscular arteries and capillaries in the lungs, as well as the kidney.

Increased ACE activity has been reported in conditions involving stimulation of the monocytic cell line, primarily granulomatous diseases. Sarcoidosis, with or without pulmonary involvement, is the most frequent and the best studied of these diseases. Serum ACE levels have been found to be correlated with granuloma burden, however, its utility as a diagnostic marker is limited, but it is often used to support a diagnosis of sarcoidosis along with other highly specific diagnostic features found in biopsies or radiography. ACE can be also increased in other granulomatous and non-granulomatous diseases such as silicosis and asbestosis, in extra-thoracic granulomatous pathologies such as Gauchers disease and leprosis, and, to a lesser extent, in non-granulomatous disorders such as hyperthyroidism or cholestasis. Extremely elevated serum ACE levels have also been found in individuals with familial ACE hyperactivity and ACE genetic mutations. Low levels are found in patients taking ACE inhibitors or corticosteroids. The reference Range is method dependent, but typically 12-40 U/L.

Scope:
Three liquid human serum samples are distributed bimonthly, with a minimum of 18 samples distributed over the year covering a wide, clinically relevant range. A panel of 7 samples are produced from blood donations from healthy volunteers and patients to cover the normal and pathological clinical range. Four of the pools are distributed 3 times and 3 pools distributed twice.

The programme assesses both laboratory and method performance, including bias, within and between batch imprecision and linearity.

Key Features:

Liquid human serum samples require no pre-analytical preparation.
Endogenous samples commutable across all testing platforms.
Pathological range covered.
Scoring based on Milan Model 3 performance specification.
Each donation is distributed on a number of occasions over the year to assess both laboratory and method performance, including bias, within and between batch imprecision.