A Study of Hormone Profiles in Critically Ill Patients: An Evidence for Hypothalamic Suppression

This study was undertaken to define hormonal (thyroid, gonadal and pituitary) changes in 25 critically ill Libyan male patients including acute myocardial infarction (AMI: 5 cases, age 45-62 years), congestive cardiac failure (CCF: 5 cases, age 44-56 years), respiratory failure (RF: 5 cases, age 34-48 years), acute renal failure (ARF: 5 cases, age 22-42 years), and diabetic ketoacidosis (DKA: 5 cases, age 35-60 years). Serum T3, T4, fT4, TSH, testosterone (Test), LH, FSH and prolactin (PRL) were estimated by RIA technique in patients during acute illness, clinical recovery and follow up as well as in Control Subjects (CS). During acute illness T3 levels in all the patients were significantly reduced compared to CS (p<0.05). T4 levels were also significantly reduced in RF (p<0.02) and DKA (p<0.05) but remained unaffected in AMI, CCF and ARF (p>0.05). Despite low T3 and low normal T4 levels during acute illness, TSH level was not elevated suggesting suppression of its secretion due to critical illness. During recovery phase, T3 and T4 levels were raised to normality (p<0.05) with marked elevation of TSH level (P<0.05) suggesting recovery of hypothalamopituitary thyroid axis from stress inhibition of critical illness. The rise in T3 and T4 levels was observed to be related to the rise in TSH level suggesting that TSH may have an essential role in restoring T3 and T4 levels to normal during recovery from critical illness. During follow up, T3, T4 and TSH levels were within normal ranges (p>0.05). The fT4 levels remained normal during various phases of illness. Serum TEST, LH and FSH levels were depressed significantly during the phase of acute illness (p<0.05) except that LH levels remained normal in CCF, ARF and DKA (p<0.05). During clinical recovery serum TEST, LH and FSH levels rose to normal suggesting existence of transient hypogonadotropic hypogonadism in critical illness. Serum PRL levels were very high during acute illness (p<0.02) which fell to normal levels during clinical recovery (p>0.05) except in case of RF suggesting suppression of tuberohypophyseal dopaminergic neuron system in critical illness. During follow up the hormone levels were observed to be within normal ranges (p>0.05). Therefore, the hormonal changes observed during the phase of acute illness in critically ill patients and suggesting hypothyroidism and hypogonadism were transitory in nature and taken as evidence for central suppression, most probably hypothalamic.