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Article
October 1985

Angiotensin-Converting Enzyme ActivityA Potential Marker of Tissue Hypothyroidism in Critical Illness

Author Affiliations

From the Department of Clinical Physiology, Walter Reed Army Institute of Research, Washington, DC (Dr Smallridge); Department of Critical Care Medicine, Bethesda (Md) Naval Hospital (Drs Chernow and Zaloga); Department of Critical Care Medicine (Dr Snyder) and Endocrinology Service, Departments of Medicine and Clinical Investigation (Drs Smallridge and Burman), Walter Reed Army Medical Center, Washington, DC; and Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md (Drs Smallridge, Chernow, Zaloga, and Burman).

Arch Intern Med. 1985;145(10):1829-1832. doi:10.1001/archinte.1985.00360100091015
Abstract

• We measured serum angiotensin-converting enzyme (ACE) activity radiometrically as a possible indicator of reduced thyroid function in 57 euthyroid controls, 27 patients in a noncardiac intensive care unit (13 with medical and 14 with surgical disorders), and 29 patients having coronary artery bypass grafting. In the last group, blood was obtained preoperatively and one day and one month after surgery (group 1; n=18) or preoperatively and six hours and one day after surgery (group 2; n =11). Patients in group 1 had significant reductions in levels of serum thyroxine (T4), triiodothyronine (T3), and thyrotropin response to protirelin one day postoperatively. The ACE activity fell significantly. Patients in group 2 had low levels of T4, T3, thyrotropin, and ACE six hours postoperatively. All these levels remained low the next day, and free T4 and free T3 levels were also reduced; the reverse T3 level became elevated. Changes in ACE significantly paralleled changes in T3. The 27 patients without coronary artery bypass grafting also had significant reductions in serum T4, T3, and ACE levels. Dilution studies and dialysis of serum with low ACE activity failed to demonstrate an inhibitor to explain the reduced enzyme function.

(Arch Intern Med 1985;145:1829-1832)

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