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Introduction ⬇

Angiotensin I is produced by the action of renin on angiotensinogen. Angiotensin I–converting enzyme (ACE) catalyzes the conversion of angiotensin I to the vasoactive peptide angiotensin II. Angiotensin I is concentrated in the proximal tubules.

This test is used primarily to evaluate the severity and activity of sarcoidosis. Serial determinations may be helpful in following the clinical course of the disease with steroid treatment. It is also used in the investigation of Gaucher disease.

Normal Findings ⬆ ⬇

Angiotensin I: <25 pg/mL or <25 ng/L

Angiotensin II: 10–60 pg/mL

ACE: 8–53 U/L or 0.14–0.88 μkat/L

Check with your laboratory for reference values for infants and children because they are generally higher. Also, check with your laboratory for test method because reference values are based on method used for assay.

Procedure ⬆ ⬇

  1. Obtain a 5-mL venous blood sample (red-topped tube). Serum or heparinized plasma is used.

  2. Observe standard precautions. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

  3. Freeze the specimen if the test is not performed immediately.

Clinical Implications ⬆ ⬇

  1. Increased ACE levels are associated with the following conditions:

    1. Sarcoidosis (ACE levels reflect the severity of the disease, with 68% positivity in stage 1 disease, 86% in stage 2, and 92% in stage 3)

    2. Gaucher disease (lysosomal storage disease)

    3. Hansen disease (leprosy)

    4. Acute and chronic bronchitis

    5. Connective tissue diseases

    6. Amyloidosis

    7. Pulmonary fibrosis

    8. Fungal diseases and histoplasmosis

    9. Untreated hyperthyroidism

    10. Diabetes

    11. Psoriasis

  2. Decreased ACE levels occur in the following conditions:

    1. Following prednisone treatment for sarcoidosis (steroid therapy)

    2. Advanced lung neoplasms

    3. Starvation

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and blood-drawing procedure.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor as appropriate for sarcoidosis and amyloid disease.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. This test should not be done in persons younger than 20 years because they normally have a very high level of ACE.

  2. About 5% of the normal adult population has elevated ACE levels.

  3. ACE is inhibited by EDTA anticoagulant.

  4. Some antihypertensive drugs may cause low ACE values.