Angiotensin Converting Enzyme |
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Angiotensin converting enzyme (ACE) participates in the renin cascade in response to hypovolemia, by converting angiotensinogen I to angiotensinogen II. The latter hormone is a potent vasoconstrictor that increases blood pressure. The endothelium of the lung is the primary source of ACE. Because of this location, ACE production is increased in sarcoidosis. Serum ACE concentration is elevated in 79% of patients with active sarcoidosis. ACE activity reflects disease activity. Levels are higher in stage III than in stage 1 disease. Enzyme activity decreases dramatically in some patients after prednisone therapy.
Other diseases such as Gaucher's disease, leprosy, histoplasmosis, amyloidosis, untreated hyperthyroidism, psoriasis and chronic renal disease have also been associated with increased ACE levels. Serum ACE is significantly decreased in patients taking ACE inhibitors such as Vasotec and captopril. Corticosteroids may slightly decrease ACE values.
Adult reference range is 7 to 46 U/L. Children and adolescents normally have values as much as 50% higher.
Specimen requirement is one red top or SST tube of blood. Lavender top tubes should not be used because EDTA inhibits the enzyme.
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