Angiotensin converting enzyme (ACE)

General Information

Angiotensin-converting enzyme is a key component of the renin-angiotensin system, which is involved in blood pressure regulation by regulating circulating blood volume.

Angiotensin-converting enzyme (also known as kinase II) is an enzyme of the hydrolase class located in the cell membrane. 90% of angiotensin-converting enzyme is bound to tissues and only a small part circulates freely in the plasma. It is mainly produced in the endothelium of the lung.

The enzyme participates in the renin-angiotensin-aldosterone reaction cascade. In response to hypovolemia (low blood pressure), the hormone angiotensin I converts to active angiotensin II, which is a vasoconstrictor. Thus, angiotensin-converting enzyme indirectly increases blood pressure. Angiotensin-converting enzyme also inhibits (blocks) bradykinin (kallikrein-kinin system).

Angiotensin-converting enzyme activity increases in sarcoidosis, a systemic granulomatous disease with lung damage. In sarcoidosis, angiotensin-converting enzyme is actively produced not only in the lung epithelium, but also in macrophages. Patients with tuberculosis or Hodgkin's lymphoma, who have developed a radiological picture similar to sarcoidosis, do not have an increase in the level of angiotensin-converting enzyme, which is an important factor for differential diagnostics.

Angiotensin-converting enzyme activity increases in direct proportion to the severity of sarcoidosis: in the first stage of the disease, the test is positive in 68% of cases, in the second stage in 86%, and in the third stage in 91%. As the disease progresses towards pulmonary fibrosis, the concentration of angiotensin-converting enzyme also decreases. Enzyme activity significantly decreases during the period of remission achieved with corticosteroids.

Assessment of angiotensin-converting enzyme activity is also informative after treatment with cytostatics (cytotoxic drugs against cancer and other processes).

When is the survey conducted?

• When sarcoidosis is suspected
• To assess the severity and activity of sarcoidosis
• To evaluate the activity of sarcoidosis in response to corticosteroid therapy

Preliminary preparation: the research can be carried out both on an empty stomach and after eating. It is not recommended to conduct research during treatment with angiotensin-converting enzyme inhibitors (captopril, enalapril and others).

Study sample: Venous blood

Reference limits:

>18 years and above: 20 – 70

<18 years: 33 – 112

Interpretation of results

Elevated angiotensin-converting enzyme activity, along with radiological evidence of pulmonary infiltrates, adenopathy, and granulomas, confirms the diagnostics of sarcoidosis.

A decrease in angiotensin-converting enzyme activity in response to corticosteroid treatment indicates a favorable prognosis of the disease.

In addition to sarcoidosis, increased or decreased angiotensin-converting enzyme activity may be associated with a variety of conditions:

Approximately 5% of the healthy adult population may have elevated angiotensin-converting enzyme levels.

An increase in the activity of angiotensin-converting enzyme is also observed in other granulomatous diseases, so the study is not used in isolation to diagnose sarcoidosis.

Angiotensin-converting enzyme levels may be 50% higher in children than in adults.

Angiotensin-converting enzyme activity is about 30% lower in smokers.

Hemolytic and hyperlipemic blood sample - gives wrong results of research