What this test measures
Serum ACE measures the activity of angiotensin-converting enzyme — an enzyme normally produced by vascular endothelium and macrophages that converts angiotensin I to angiotensin II (a step in blood pressure regulation). In sarcoidosis, activated macrophages in non-caseating granulomas produce excess ACE, raising serum levels.
The test is reported in U/L. It is not a diagnostic test for sarcoidosis on its own — sensitivity is only about 60% and specificity about 70–85%, with false positives in diabetes, hyperthyroidism, liver disease, and other granulomatous conditions (TB, leprosy, fungal disease). Genetic ACE polymorphisms also influence baseline levels.
Why it matters
Sarcoidosis is a multisystem granulomatous disease that can affect lungs, lymph nodes, eyes, skin and other organs. In India, distinguishing pulmonary sarcoidosis from tuberculosis is a major clinical challenge — both can cause hilar lymphadenopathy and lung infiltrates, but treatment is very different (steroids for sarcoidosis, ATT for TB). ACE is one supporting test among many — alongside high-resolution CT, bronchoalveolar lavage, biopsy showing non-caseating granulomas (with exclusion of TB), and clinical features.
ACE is also used to monitor disease activity in known sarcoidosis patients — levels often fall with response to steroids/immunosuppression and rise with relapse. Caveat: ACE inhibitors (commonly used for hypertension and heart failure) dramatically lower ACE activity and produce false negatives.
How to prepare
No fasting required. Tell your doctor if you take ACE inhibitors (enalapril, lisinopril, ramipril) — these block the enzyme and falsely lower the result. If possible, ACE inhibitors are held for several days before testing (only under medical supervision).
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Serum ACE (U/L)[1][2][3] | 8–52 U/L (assay-dependent) | Low — typical of ACE inhibitor therapy, advanced liver disease, hypothyroidism, anorexia. Not clinically concerning otherwise. | Elevated — sarcoidosis (most common reason for elevation), but also TB, leprosy, fungal granulomatous disease, hyperthyroidism, Gaucher disease, diabetes. Use as supportive marker alongside imaging and biopsy. |
Conditions affecting serum ACE
| Direction | Conditions |
|---|---|
| Increased | Sarcoidosis, TB, leprosy, histoplasmosis, hyperthyroidism, Gaucher disease, diabetes |
| Decreased | ACE inhibitor therapy, advanced liver disease, hypothyroidism, severe malnutrition |
Frequently asked questions
Can ACE diagnose sarcoidosis on its own?
No. ACE has only 60% sensitivity and false positives in TB and other conditions. Diagnosis requires clinical features, imaging, and usually biopsy showing non-caseating granulomas with TB excluded.
Do I need to fast?
No fasting required.
What if I take an ACE inhibitor (e.g. ramipril)?
ACE inhibitors block the enzyme and falsely lower the result. Tell your doctor — testing on these medications is not informative.
How is ACE used in monitoring sarcoidosis?
Falling ACE levels often track response to corticosteroids; rising levels can suggest relapse. But ACE does not closely track all aspects of disease activity, so doctors also use imaging and clinical assessment.
Is ACE elevated in TB?
Yes — TB is a common cause of false-positive elevation in India and a key reason ACE alone cannot diagnose sarcoidosis here.
How long does the report take?
Typically 2–3 days.
Related Toxicology / Trace Elements tests
Tests commonly ordered alongside ANGIOTENSIN CONVERTING ENZYME, or that help interpret an unexpected result.
Sources & references
- NIH MedlinePlus — Angiotensin-Converting Enzyme Test · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Sarcoidosis · accessed 2026-05-30T00:00:00.000Z
- ATS/ERS/WASOG — Sarcoidosis Statement · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Labs — Angiotensin-Converting Enzyme · accessed 2026-05-30T00:00:00.000Z
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