Inflammation and immunity
ACE
An enzyme that is often raised in sarcoidosis; supports the diagnosis and monitoring of that disease.
Everything about this testWhat it measures
ACE (angiotensin-converting enzyme) converts angiotensin I into angiotensin II in the body, a substance that narrows the blood vessels and raises blood pressure. The enzyme is found mainly in the blood vessels of the lungs. In sarcoidosis, small inflammatory nodules (granulomas) form in organs, and their cells make extra ACE, so the value in the blood rises. The higher the disease activity and the more granulomas, the higher the value usually is.
- Sarcoidosis, an inflammatory disease with granulomas, usually in the lungs and lymph nodes
- The course of sarcoidosis: whether the disease is active or responding to treatment
High
A raised value may fit sarcoidosis. Symptoms that go with it are tiredness, fever, weight loss, night sweats, shortness of breath, dry cough, joint pain, swollen lymph nodes and eye problems. A raised value also occurs without sarcoidosis: in young people under twenty, ACE is naturally higher, and an overactive thyroid, diabetes, smoking, excessive alcohol use and liver disease can also raise the value.
Low
A low value is most often caused by ACE inhibitors, blood pressure medicines such as enalapril, lisinopril and perindopril; they block the enzyme and often give a very low result. An underactive thyroid can also lower the value. A low value causes no symptoms itself. A normal or low value does not rule out sarcoidosis.
If your result is abnormal
With a raised value and matching symptoms, the GP usually arranges a chest X-ray and, if sarcoidosis is suspected, refers you to a lung specialist. With a slightly raised value without symptoms, there is usually no follow-up, or a repeat test after some time.
Reliability
A raised ACE is not enough to diagnose sarcoidosis, and a normal ACE does not rule out the disease: according to the Dutch Society for Clinical Chemistry (NVKC), about 15 in 100 people with sarcoidosis have a normal value. In other lung diseases that resemble sarcoidosis, such as tuberculosis and pulmonary fibrosis, ACE is also often normal. The result is mainly meaningful with symptoms that fit sarcoidosis, together with a chest X-ray, lung function tests and sometimes other blood values, and for monitoring known sarcoidosis. In people without symptoms, a slightly raised value says little.
Limitations
- ACE inhibitors (blood pressure medicines such as enalapril, lisinopril and perindopril) lower the value sharply; the result then cannot be used.
- In young people under twenty, the value is naturally higher.
- An inherited variation in the ACE gene partly determines how high a person's value is; the normal spread between people is large.
- Reference values differ per laboratory and per measurement method.
How common is this
Sarcoidosis is a rare disease; in the Netherlands, an estimated 1 to 2 in 10,000 people have the disease, usually between the ages of 20 and 40. In some people, the disease disappears on its own within a few years.
Who is this useful for
The result is mainly meaningful with symptoms that fit sarcoidosis, such as long-lasting tiredness with shortness of breath, dry cough, swollen lymph nodes, eye inflammation or an unusual skin rash, and for monitoring known sarcoidosis. In people without symptoms, a slightly abnormal value says little. If you use an ACE inhibitor, the result cannot be interpreted.
Downsides and risks
- A slightly raised value without symptoms can cause unnecessary worry or lead to unnecessary follow-up testing, such as a chest X-ray.
- A normal value can give false reassurance, because sarcoidosis also occurs with a normal ACE.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results