Also Known As
SACE (Serum Angiotensin Converting Enzyme)
Formal Name
Angiotensin Converting Enzyme
This article was last reviewed on
This article waslast modified on 2 May 2023.
At a Glance
Why Get Tested?

To sometimes help diagnose and monitor sarcoidosis and to help distinguish it from other diseases which show similar symptoms

When To Get Tested?

When you have granulomas (masses of inflammatory cells) that create small bumps under the skin, a lingering cough, red watery eyes and/or other symptoms suggestive of sarcoidosis. When you have active sarcoidosis in order to follow its progress

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

No test preparation is needed

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

Angiotensin converting enzyme (ACE) is an enzyme which helps regulate blood pressure. It converts angiotensin I (an inactive protein) to angiotensin II which causes arteries to contract, making them temporarily narrower and increasing the pressure of the blood flowing through them. ACE is produced throughout the body, but is present in especially high amounts within the lungs.  It is normally found at a high concentration in the bloodstream of those less than 20 years of age, and will usually then drop to lower concentrations in healthy adults.

Increased amounts of ACE are sometimes produced by cells found at the outside borders of granulomas. Granulomas are a classic feature of sarcoidosis, a disorder that often affects the lungs but may also affect many other body organs including the eyes, skin, nerves, liver, and heart. The cause of sarcoidosis is unknown. About 75% of patients with untreated sarcoidosis will have elevated concentrations of ACE in their bloodstream that will rise and fall as the severity of the disease changes. Granulomas, fibrosis, and an elevated ACE concentration may also be seen in infections such as leprosy and tuberculosis. The granulomas form around the invading bacteria in these infections and can also form around irritant particles in poisons such as beryllium, asbestos, and silicon.


Accordion Title
Common Questions
  • How is it used?

    Although ACE measurement may not be needed in the diagnosis and monitoring of many patients with sarcoidosis, it can be used to help diagnose and monitor sarcoidosis in some patients. 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 around 75% of patients with untreated 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.

  • 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 X-rays, CT-Scan, tissue biopsies, 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 result was elevated, your doctor may request ACE testing at regular intervals to monitor the change in concentration over time.

  • What does the test result mean?

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

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

    High concentrations of ACE are often observed initially in sarcoidosis, which then decrease with time, which suggests the activity of the disease has decreased without obvious reason or as a result of therapy. Falling concentrations usually indicate a favourable prognosis. Rising concentrations 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.

  • 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 by 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.

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

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

    The ACE test is not useful in diagnosing or monitoring any of these disorders.

  • What other tests are used to diagnose sarcoidosis?

    A variety of tests may be requested to help diagnose sarcoidosis and to discover the extent of the disease. Laboratory tests may include: liver function tests, full blood count, and calcium. Other tests may include an examination for skin problems, a lung function test (about 90% of the time there will be evidence of lung disease in patients with sarcoidosis), bronchoscopy (passing a flexible tube that is used to look at the lining of the airway and to biopsy the lung), chest x-ray, PET or CT scanning. Biopsies of the skin, lungs, lymph nodes and sometimes liver may also be needed, as may a thorough eye examination (a test called a slit-lamp examination may be used). There is a biomarker (blood test) that appears to perform better than ACE for diagnosing sarcoidosis, soluble interleukin 2 receptor (sIL-2R), however it is not yet routinely available in clinical practice.

  • What causes sarcoidosis?

    The cause is not well understood. It is not easily spread. It is inflammatory and involves the immune system. It appears to have a genetic and environmental association. It is relatively common in Scandinavia and Northern Ireland, but rare in China, Japan, and Africa. For some reason, those who move from a part of the world where the disease is very uncommon to a part of the world where it is common will have a higher risk of developing the disease.

  • What is the long-term prognosis for sarcoidosis?

    The majority of those with sarcoidosis recover from the disease over a period of several months to a couple of years, but some may suffer permanent scarring in their lungs. Early detection can help better manage the disease although many cases resolve themselves without any treatment.