الفهرس 
PHYSIOLOGY OF STEROIDSOnly 14 pages are availabe for public view
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Abstract
Corticosteroids are a group of natural and synthetic analogs of the hormones secreted by the pituitary gland, also known as the hypothalamic-anterior pituitary-adrenal (HPA) axis. These analogs include cortisol which is anti-inflammatory agent with a large number of other functions; aldosterone, which control salt and water balance primarily through action on the kidneys; and corticotrophins, which control secretion of hormones by the pituitary gland.
During stress, CRH released from hypothalamus resulting in release of ACTH from anterior pituitary gland which causes cortisol secretion from adrenal gland then cortisol binds to GC receptors leading to up-regulation of ant-inflammatory proteins expression and down regulation of pro-inflammatory proteins expression.
Corticosteroids are widely used in ICU because they have many effects on:
• Glucose, protein and lipid metabolism.
• immunity
• fluid haemostasis
• Central nervous system.
As steroids can improve oxygenation, lung function and reduce inflammation hypersensitivity, they are the most important treatment for status asthmaticus, COPD and ARDS.
Also, low dose of steroids with their anti-inflammatory effect has a significant role in treatment of septic shock. It is relatively safe, can reduce the time to reversal of shock and decrease the mortality rate. So, Serviving Sepsis Campaign recommends the addition of IV steroids to the patients with septic shock whom don’t respond to fluids or vasopressors resuscitations.
However, neurological diseases require steroidal therapy, because of its action to prevent or reduce the cerebral edema produced by infection or neoplasm. So, steroids are adjunctive treatment for bacterial meningitis as dexamethasone should be administered just before or with the first dose of antibiotic therapy when suspected.
Early steroid therapy (within the first 8 h) has a significant effect on treatment of spinal cord injury. It helps in improvement of the function and better outcome.
Corticosteroids have a broad spectrum effect in immune cells and they inhibit pro-inflammatory gene expression so, they are commonly used in treatment of auto-immune diseases and even with very high doses in acute allograft rejection.
Indeed, steroids are included in every regimen of several neoplasms as: acute lymphoblastic leukemia, Hodgkin and non-Hodgkin lymphoma, breast cancer and central nervous system tumors. They reduce or prevent peritumoral edema, inflammation and the pain from metastases.
There are many other uses of corticosteroids, as in perioperative period they used a replacement therapy in patient undergoes separation of pituitary adrenal axis with previous steroid intake. Perioperative steroid therapy should be considered in all patients who received steroids for at least one month at the previous 6-12 months.
Use of physiologic stress dose of hydrocortisone improves the outcome of high risk patients; reduce the incidence of AF after cardiac surgery and the symptoms of PTSD after recovery.
They also used in treatment of postoperative nausea and vomiting. It is found that 10 mg of dexamethasone is highly effective when given immediately before induction rather than at the end of anesthesia.
As well as, they decrease the production of inflammatory mediators which participate in pain perception. So, steroids have analgesic effect. All of these properties reduce the length of stay in hospital helping the early discharge and better patient satisfaction.
Several studies reported that critically ill patients with end-stage liver disease commonly have adrenal insufficiency. So, their treatment with corticosteroids may improve the patients’ outcome.
Although, these many uses of corticosteroids in ICU, corticosteroids appears to be associated with a great risk for complications which depend on the dose and the duration of the treatment.
These complications include:
1. Deficiency of the immunity, increase the risk of the infection (acquired hospital infection, pneumonia, urinary tract infection, bacteremia and fungal infection).
2. Impaired glucose tolerance and hyperglycemia or worsening of the diabetes.
3. Metabolic and electrolyte disturbance,
4. Neuromyopathydisorders.
5. Poor wound healing.
6. Suppression of HPA axis and withdrawal syndrome.
So, high doses of corticosteroids are not recommended because they increase the length of stay in hospital, the morbidity and the mortality rate.
It is clearly that corticosteroids are very important drugs commonly used in ICU due to their significant properties and effects, but they have some serious side effects which should be considered when used. So it is recommended to measure the risk/ benefit ratio if they are indicated in treatment of critically ill patients.