Evaluation of serum angiotensin converting enzyme [SACE] as a diagnostic marker for pulmonary embolism

ABSTRACT

A number of supportive laboratory tests such as ECG, Chest x-ray, ABGs, SLDH, SGOT, S. Bilirubin and D-dimer with variable sensitivity and specificity are available to facilitate the clinical diagnosis of acute Pulmonary Embolism [PE]. Serum Angiotensin Converting Enzyme [SACE] which is produced mainly by the pulmonary vascular endothelial cells, is found altered during a variety of diffuse lung diseases. This study was designed to evaluate the validity of SACE level as a marker for hypoxic damage to the pulmonary endothelium in PE. Design: A prospective study carried out on forty patients with high clinical suspicion of PE. Besides routine diagnostic tests mentioned above all of them had Ventilation Perfusion isotope [V/Q] scans [as a diagnostic test] and SACE level checked. Setting: Shaikh Zayed Hospital Lahore. Results. Among forty consecutive patients with age range 25-59 years [mean 42 Yr], twenty six patients [65%] with abnormal scans reported as High Probability' were included in group-A [True Positive], whereas 14[35%] patients having Low-Probability [Suspected] or Normal scan were included in group-B, Low SACE level [<28iu/L] was found in 19/26 [sensitivity of 73%] in Group-A [Positive Predictive Value 47%] and 9/14 [sensitivity of 64%] in Group-B, whereas mean levels for both groups were 34.55 and 54.84 respectively. Rise in LDH was pronounced in Group-A. Only chest X-ray and ECGs were found to be more sensitive for group-A than group-B. Changes in ABGs [Type-1 Resp. Failure] had low sensitivity. Among clinically suspected cases of PE, fall in SACE level can be used as a sensitive and reliable diagnostic marker as more than 75% of the enzyme is produced in the lungs compared with other enzymes which have extra-pulmonary source