Angiotensin Converting Enzyme - ACE (Liquor)

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 is elevated in approximately 55% of patients with neurosarcoidosis, 5% of patients with sarcoidosis without signs of neurological damage, and 13% of patients with other neurological diseases.

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 neurosarcoidosis is suspected
• To evaluate the effect of treatment of neurosarcoidosis

Pretreatment: Antihypertensive drugs such as ACE inhibitors, angiotensin receptor blockers, and diuretics may cause false test results.

Study sample: cerebrospinal fluid (CSF)

Reference limits:

< 2 units/l

Interpretation of results

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

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.