Hypothyroidism is a common disorder affecting the cardiovascular, respiratory, 
hematopoietic, and renal organ systems--each of which is particularly germane in 
the management of the surgical patient. In general, treatment of recognized 
hypothyroidism is recommended before any surgical procedure whenever possible 
and euthyroidism should be documented by measurement of serum TSH as part of the 
preoperative evaluation. Such a strategy is likely to result in better surgical 
outcomes with improved morbidity and mortality. One exception to treating first 
with thyroid hormone is the patient with angina or coronary artery disease 
requiring bypass grafting, angioplasty or stenting. In this setting, 
preoperative thyroid hormone therapy could tax the ischemic myocardium. The 
coronary blood flow should be addressed first, and thyroid hormone therapy 
initiated afterwards. The authors have emphasized the need for caution in the 
interpretation of low serum thyroid hormones in sick or surgical patients 
because of the importance of distinguishing between hypothyroidism and the 
"euthyroid sick syndrome." There is no clear evidence at this point to support 
thyroid hormone replacement in the latter patients, and it may be potentially 
harmful. Rather, we hold that T3 treatment of various surgical and other 
patients with nonthyroidal illness should be deferred until proof of its 
therapeutic efficacy is demonstrated.