Systemic illness

Abstract

Systemic illnesses are associated with alterations in the hypothalamic-pituitary-peripheral hormone axes, which represent part of the adaptive response to stressful events and may be influenced by type and severity of illness and/or pharmacological therapy. The pituitary gland responds to an acute stressful event with two secretory patterns: adrenocorticotropin (ACTH), prolactin (PRL) and growth hormone (GH) levels increase, while luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyrotropin (TSH) levels may either decrease or remain unchanged, associated with a decreased activity of their target organ. In protracted critical illness, there is a uniformly reduced pulsatile secretion of ACTH, TSH, LH, PRL and GH, causing a reduction in serum levels of the respective target-hormones. These adaptations are initially protective; however, if inadequate or excessive they may be dangerous and may contribute to the high morbidity and mortality risk of these patients. There is no consensus regarding the type of approach, as well as the criteria to use to define pituitary axis function in critically ill patients. We here provide a critical approach to pituitary axis evaluation during systemic illness.

Measurement of cardiac output using the transpulmonary thermodilution method in the presence of high extravascular lung water in a pediatric animal model

“…In men, independently of age, hypogonadism was considered when plasma testosterone levels were below 3 ng/ml [17]. Hypogonadism was considered secondary (SH) when FSH and LH concentrations were below 5 mU/l and primary (PH) when FSH and LH levels were above 10 mIU/l [17].…”

Anterior Pituitary Failure

“…Changes in hypothalamic and pituitary function are evident in acute illness, and may be adaptive responses to critical illness. Diagnosing adrenal insufficiency in the ICU setting is challenging due to multiple factors including a lack of uniform criteria for the diagnosis, physiological factors affecting free and total serum cortisol levels, the lack of an appropriate test, and the lack of reliable methods to measure free cortisol levels in serum [173]. Basal levels of total serum cortisol may indicate adrenal insufficiency, but cutoff levels vary widely in the literature.…”

“…Patients with albumin levels less than 2.5 g/dl may be best identified as adrenally insufficient with a cutoff level of 10 mg/dl [174e176]. Measurements of serum-free cortisol, either directly or through the use of a calculated index, are appealing but not widely available or rapidly performed [173,177]. Dynamic testing carries undue risk to critically ill patients (ITT, metyrapone), are not validated in this setting (CRH stimulation, glucagon, lowdose ACTH stimulation), or do not reflect pituitary insufficiency (all ACTH stimulation tests).…”

Pituitary Insufficiency after Infectious Meningitis: A Prospective Study

“…Hyperprolactinemia was defined as a basal serum PRL above the reference level, taking into account gender and menstrual history. The presence of relative pituitary hormonal deficiency during the acute presentation was not considered as definite due to the known suppressive effect that acute illness may exert on pituitary function that does not necessarily imply structural damage (8).…”