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ACE

Also known as: SACE (Serum Angiotensin Converting Enzyme)
Formal name: Angiotensin Converting Enzyme
Related tests: AFB culture; Liver panel; FBC; Calcium

The Test

How is it used?

ACE is usually requested to help diagnose and monitor sarcoidosis. It is often requested as part of an investigation into the cause of a group of long troubling symptoms that may or may not be due to sarcoidosis. ACE will be elevated in 50-80% of patients with active sarcoidosis. If it is initially elevated in someone with sarcoidosis, ACE can be requested at regular intervals to monitor the course of the disease and the effectiveness of corticosteroid treatment.

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When is it requested?

ACE is requested when you have signs or symptoms such as granulomas, a chronic cough or shortness of breath, red watery eyes, and/or joint pain that may be due to sarcoidosis or to another disorder. Sarcoidosis is most commonly seen between 20 and 40 years of age. Your doctor may request ACE with other tests such as an AFB culture or sputum culture (tests that can detect mycobacterial and fungal infections), to help differentiate between sarcoidosis and another granulomatous condition.

If when you were diagnosed with sarcoidosis, your initial ACE levels were elevated, your doctor may request ACE testing at regular intervals to monitor their change over time.

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What does the test result mean?

Looking for reference ranges?

If someone is under 20 years of age, then high ACE levels do not usually indicate disease. For those over 20 years of age, ACE blood levels do not tell you why the levels are elevated, what organs and/or body systems are involved, or how badly they are affected. ACE does not cause granulomas but may reflects their presence.

If ACE levels are high, other diseases have been ruled out and you have clinical symptoms of sarcoidosis, then it is likely that you have an active case of sarcoidosis. About 20-50% of the time, however, sarcoidosis can be present without elevated ACE levels. This may be due to the disease being in an inactive state, due to an early detection ofsarcoidosis where the levels have not yet risen, or due to the fact that the cells do not produce increased amounts of ACE. A normal ACE level cannot be used to rule out sarcoidosis. ACE levels are also less likely to be elevated in those with long term sarcoidosis.

High levels of ACE are often observed initially in sarcoidosis, which then decrease with time, which suggests the activity of the disease has without obvious reason or following therapy. Falling levels usually indicate a favourable prognosis. Rising levels of ACE on the other hand, may indicate either an early disease process that is progressing, or disease activity that is not responding to therapy.

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Is there anything else I should know?

ACE conversion of angiotensin I to angiotensin II is a normal regulatory process in the body. This process is targeted in drugs called ACE inhibitors that are commonly used in treating hypertension and diabetes. These drugs inhibit the conversion process, keeping the blood vessels more dilated and the blood pressure lower. ACE inhibitors are useful in managing hypertension but they are not monitored with ACE blood tests. They may however interfere with ACE measurements requested for other reasons.

Haemolysis (broken red blood cells) and hyperlipidaemia (excess fats) in the blood sample may falsely decrease ACE levels. Decreased ACE levels may also be seen in patients with:

ACE has been found in moderately increased levels in a variety of diseases and disorders such as:

  • HIV
  • Certain fungal diseases
  • Diabetes mellitus
  • Hyperthyroidism
  • Lymphoma
  • Alcoholic cirrhosis
  • Gaucher’s disease (a rare inherited lipid metabolism disorder)
  • Tuberculosis
  • Leprosy
The ACE test, however, is not routinely used to diagnose or monitor these conditions (it had not been shown to be clinically useful).

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