Angiotensin-converting enzyme activity in acute illness

Estimation of ACE activity is not reliable for making the diagnosis of sarcoidosis because elevations are present in disorders of diverse etiologies. Nevertheless, sequential ACE measurements may assist in assessing the course of the disease. Many illnesses are associated with reduced activity of this enzyme, for reasons that are presently obscure. However, an awareness of this phenomenon is necessary because acute illness may lower serum ACE in diseases with otherwise elevated levels of ACE, thus limiting the utility of this test in acutely ill patients. Regardless of the reason for low activity, ACE may become useful in predicting outcome in some illnesses. Recent clinical studies indicate that thyroid hormone and probably other hormones and metabolic factors influence this enzyme's activity. Further investigations will hopefully elucidate the roles and nature of these modifying factors.