Physiological effects of nonthyroidal illness syndrome in patients after cardiac surgery.
In a prospective randomized placebo-controlled study, we assessed potential physiological effects of nonthyroidal illness syndrome (NTIS) in acute illness. Coronary artery bypass graft surgery was employed as a prospective model of acute illness and NTIS. Triiodothyronine (T(3)) or placebo was infused for 24 h after surgery, with a T(3) dose selected to maintain postoperative serum T(3) concentrations at preoperative levels. Patients were evaluated before coronary artery bypass graft and during the postoperative period. Cardiovascular function was monitored with Swan-Ganz catheter measurements and ECG. Urinary nitrogen excretion and L-[1-(13)C]leucine flux were used to evaluate protein metabolism. Serum measurements of relevant hormones, iron, and total iron-binding capacity were used to assess effects on sex steroid, growth hormone axis, and iron responses to illness. Cardiovascular function was not affected by T(3) infusion, except for a transient higher cardiac index in the T(3) group 6 h after surgery (3.04 +/- 0.12 for T(3) and 2.53 +/- 0.08 for placebo, P = 0.0016). Protein metabolism was not affected; changes in urinary nitrogen excretion and L-[1-(13)C]leucine flux were equivalent in the two groups (P = 0.35 and P = 0.95, respectively). No differences were observed in changes in testosterone, estrogens, growth hormone, insulin-like growth hormone I, iron, or total iron-binding capacity between T(3) and placebo groups. We conclude that, in the early stages of major illness, the decrease in circulating T(3) concentrations in NTIS has only a minimal transient physiological impact on cardiac function and plays no significant role in protecting against protein catabolism or modulating other endocrine responses or iron responses to illness.
Spratt
D I
DI
Division of Reproductive Endocrinology, Department of Ob/Gyn, Maine Medical Center, Portland, ME 04102, USA. spratd@mmc.org
Frohnauer
M
M
Cyr-Alves
H
H
Kramer
R S
RS
Lucas
F L
FL
Morton
J R
JR
Cox
D F
DF
Becker
K
K
Devlin
J T
JT
D001145:Arrhythmias, Cardiac / Q000209:etiology; D001026:Coronary Artery Bypass / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005067:Euthyroid Sick Syndromes / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007501:Iron / Q000097:blood; D008297:Male; D008875:Middle Aged; D010919:Placebos; D011184:Postoperative Period; D013972:Thyrotropin / Q000097:blood; D014284:Triiodothyronine / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*
D012739:Gonadal Steroid Hormones; D010919:Placebos; D014284:Triiodothyronine; D013972:Thyrotropin; D013006:Growth Hormone; D007501:Iron