Angiotensin-Converting Enzyme
Also known as: ACE, Serum ACE
What Does Angiotensin-Converting Enzyme Measure?
Angiotensin-Converting Enzyme (ACE) is a protein enzyme found primarily in the lungs, kidneys, and blood vessels. A blood test measuring ACE determines the level of this enzyme circulating in your bloodstream. ACE plays a central role in the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure by converting angiotensin I into angiotensin II — a potent vasoconstrictor that narrows blood vessels and signals the kidneys to retain sodium and water.
Why Does Angiotensin-Converting Enzyme Matter?
Clinically, ACE levels are most commonly used to help diagnose and monitor sarcoidosis, a condition where small clusters of inflammatory cells (granulomas) form in organs, particularly the lungs. Elevated ACE is found in approximately 60–80% of active sarcoidosis cases, making it a valuable marker for disease activity and treatment response. Beyond sarcoidosis, abnormal ACE levels can indicate other granulomatous diseases, liver disorders, hyperthyroidism, or diabetes. ACE inhibitor medications — widely prescribed for high blood pressure and heart failure — work by directly blocking this enzyme, so understanding ACE biology is also important for medication management.
Normal Ranges
Males
8–52 U/L (units may vary by laboratory; some labs report 16–85 U/L)
Females
8–52 U/L (units may vary by laboratory; some labs report 16–85 U/L)
Children
Varies by age; generally higher in children under 18 (up to 2–3x adult values); consult pediatric reference ranges
Causes of High Levels
- Sarcoidosis — the most common clinical reason; activated macrophages in granulomas produce excess ACE
- Hyperthyroidism — elevated thyroid hormones can stimulate ACE production
- Diabetes mellitus — chronic hyperglycemia may upregulate ACE expression in vascular tissues
- Liver diseases such as primary biliary cirrhosis or hepatitis — damaged liver tissue can increase ACE release
- Gaucher's disease — a rare inherited lipid storage disorder where macrophage activation raises ACE
- Pulmonary fibrosis or other interstitial lung diseases — inflammatory lung tissue can produce elevated ACE
Causes of Low Levels
- ACE inhibitor medications (e.g., lisinopril, enalapril, ramipril) — directly block and suppress ACE activity
- Hypothyroidism — low thyroid hormone levels reduce ACE expression
How to Improve Your Angiotensin-Converting Enzyme
Diet
- Adopt an anti-inflammatory diet rich in fruits, vegetables, whole grains, and fatty fish (salmon, mackerel) to support vascular health
- Reduce sodium intake to below 2,300 mg/day to support the blood pressure regulatory system that ACE influences
- Incorporate fermented foods (yogurt, kefir, tempeh) as some peptides from fermented proteins have mild natural ACE-inhibitory properties
- Limit ultra-processed foods and refined sugars to reduce systemic inflammation that can drive ACE dysregulation
- Consume foods rich in omega-3 fatty acids and antioxidants (walnuts, flaxseeds, berries) to reduce oxidative stress on vascular tissue
Supplements
- Omega-3 fatty acids (fish oil): 1,000–2,000 mg EPA+DHA daily may support vascular health and reduce inflammation driving elevated ACE
- Vitamin D3: 1,000–2,000 IU daily, as deficiency has been associated with dysregulation of the renin-angiotensin system
- Magnesium glycinate: 200–400 mg daily supports vascular tone and has mild blood pressure-lowering properties linked to ACE activity
- Quercetin: 500–1,000 mg daily — a flavonoid with evidence of mild natural ACE inhibition and anti-inflammatory effects
Related Biomarkers
Frequently Asked Questions
What does a high ACE level mean?
A high ACE level most commonly raises suspicion for sarcoidosis, a condition where the immune system forms small inflammatory nodules (granulomas) in organs like the lungs. Elevated ACE can also occur with hyperthyroidism, diabetes, liver disease, and Gaucher's disease. However, ACE is not diagnostic on its own — your doctor will use it alongside symptoms, imaging, and other tests to reach a diagnosis.
Can ACE inhibitor medications affect my ACE blood test results?
Yes, absolutely. ACE inhibitors such as lisinopril, enalapril, benazepril, and ramipril directly block ACE enzyme activity, which will significantly lower your measured ACE levels. If you are on these medications, your doctor should be aware when interpreting your results, as the test may not accurately reflect underlying disease activity in conditions like sarcoidosis.
Is the ACE test used to diagnose sarcoidosis?
The ACE test is a useful supporting tool but is not sufficient to diagnose sarcoidosis on its own. ACE is elevated in about 60–80% of active sarcoidosis cases, but it can also be elevated in other conditions, and it can be normal in confirmed sarcoidosis cases. Diagnosis typically requires a combination of clinical evaluation, chest X-ray or CT scan, and tissue biopsy. ACE is most valuable for monitoring disease activity and response to treatment once a diagnosis has been established.
Why are ACE levels naturally higher in children?
Children normally have ACE levels that are 2–3 times higher than adult reference ranges. This is because ACE is closely tied to growth and development — the enzyme plays roles in bone growth, tissue remodeling, and cardiovascular development during childhood. Pediatric reference ranges differ significantly from adult ranges, so it's important to use age-appropriate standards when interpreting ACE results in children.