Endocrine problems in the chronically critically ill patient.
The endocrine adaptations to critical illness are varied. In the diabetic patient, counterregulatory hormones predispose to insulin resistance and hyperglycemia, a derangement accentuated by the use of glucocorticoids and enteral or parenteral nutrition. Thyroid abnormalities include the euthyroid sick syndrome, which may manifest as a low T3, low T4, low TSH, or all three. Illness in patients with pre-existing hypothyroidism or hyperthyroidism may precipitate myxedema coma or thyroid storm, respectively. The most important issue related to calcium is that of acute hypercalcemia, which, in the intensive care unit, usually is caused by malignancy and dehydration. Hyponatremia, a frequently encountered electrolyte disturbance, is evaluated best and treated according to volume status.