Adrenal Gland
                                =============
þ Pediatric Adrenal Insufficiency

 - Congenital adrenal hyperplasia (CAH) is an important cause of primary adrenal 
   insufficiency in the newborn period, whereas Addison’s disease is a more 
   common etiology in children and adolescents. Secondary adrenal insufficiency 
   is more common in older children and almost always involves exogenous steroid 
   use for a chronic disease with subsequent discontinuation.
 - The term congenital adrenal hyperplasia refers to a group of inherited 
   autosomal recessive disorders with defects in adrenal biosynthesis of the 
   glucocorticoid cortisol. The low cortisol production stimulates pituitary 
   production of ACTH which causes the characteristic hyperplasia of the adrenal 
   cortex. Depending on the affected enzyme, the synthesis of other steroids 
   such as mineralocorticoids (aldosterone) and androgens may also be affected, 
   and the clinical expression will vary depending on the accumulated 
   biosynthetic precursors. Deficiency of 21-hydroxylase accounts for up to 95% 
   of CAH cases, and the discussion herein is limited to this particular form of 
   CAH. This disorder occurs in 1 in 10,000 to 15,000 live births worldwide. Up 
   to 75% of affected newborns have the classic salt-losing virilizing variant, 
   which is associated with aldosterone deficiency and androgen overproduction 
   (17-hydroxyprogesterone); up to 25% have the non–saltlosing simple virilizing 
   type. The degree of virilization and other clinical signs are usually more 
   pronounced and seen earlier in life in the salt-losing variant.
 - Many states now screen newborns for CAH; however, these results may not be 
   available for several weeks, allowing for an acute adrenal crisis to occur 
   during this time. Males are particularly prone to missed diagnosis because 
   their genitalia may appear normal at birth. Females usually exhibit some 
   degree of ambiguous genitalia, such as clitoral enlargement or fusion of the 
   labial folds. Another physical examination sign is hyperpigmentation, which 
   may be present in the axilla and scrotal/labial areas and is due to the 
   accumulation of a corticotropin precursor that stimulates melanocytes. With 
   the classic salt-losing type, symptoms may begin 1 to 2 weeks after birth and 
   include weight loss, poor feeding, vomiting, polyuria, and dehydration. 
   Progression can occur rapidly, particularly in the setting of infection or 
   trauma, to altered mental status, hypotension, or death.
   [Kwon KT, Tsai VW. Metabolic emergencies. Emergency medicine clinics of 
   North America 2007;25:1041-60, vi.]
   
þ Treatment of adrenocortical insufficiency:
 - Use dexamethasone (e.g., Decadron) rather than cortisone (e.g.,
   Solu-Cortef), as won't interfere with stimulation test later.
 - Or, just draw a random cortisol level and give hydrocortisone (Solu-Cortef) 
   as it's actually better than dexamethasone. 
 - Dosing:
   Hydrocortisone:
    Infant: 25 mg
    Child: 50 mg
    Teen: 75 mg
    Adult: 100 mg
   Dexamethasone 0.1–0.2 mg/kg IV/IM
 - Potency of Steroids:
   Drug                 Glucocorticoid  Mineralocorticoid
   hydrocortisone:      1               1
   cortisone:           0.8             1
   dexamethasone:       40              none
   fludrocortisone:     15              400
    (Florinef)

þ Addison's Disease/adrenocortical insufficiency
 - Electrolytes:
  + Na+ usually low, sometimes normal
  + K+ usually a normal or a bit high
  + Glucose usually low
 - GI: anorexia, n/v/abd pain; sometimes pain is severe

þ Steroid Withdrawal
 - may take 6-12 months for adrenals to recover from high-dose steroids
   suppressing the adrenals
   [Tintinalli 3rd ed. p 761]

þ Addison's Disease associated with:
 - diabetes mellitus
 - Hashimoto's thyroiditis
 - pernicious anemia
 - or primary ovarian failure?