adrenal gland

Hypothalamus

Corticotrophin releasing hormone CRH
Anterior pituitary
Adrenalocorticotropic hormone ACTH
Adrenal gland

Adrenal gland consist of:

1. cortex: zona glomerulosa: secrete aldosterone (mineralocorticoid)
= fasciculate: secrete cortisol (glucocorticoid)
= reticularis: secrete androgen
2. medulla: secrete catecholamines (dopamine, epinephrine, norepinephr).

- most important actions of glucocort (steroid): ↑glucose production , inhibit fibroblasts (leading to atrophy & striae of the skin), ↓CNS edema
- Side Effects of steroid (CUSHINGOID MAP):
Cataract, Ulcer (GIT bleeding), Striae, Hypertension, Infec (& leucocytosis), Necrosis of bone (avascular), Growth stunting , Osteoporosis, ↑ICP, D.M, Myopathy, Adepose tissue hypertrophy (obesity), Pancreatitis.
- actions of mineralocorticoid: maintain intravascular volume by conserving Na+ & eliminating K+
- both epinephrine & norepinephrine ↑mean arterial B.P, but only epineph ↑cardiac output.

Adrenocortical insufficiency

Most important causes of Primary adrenal insufficiency are:
1) inherited etiologies: Salt-losing form of congenital adrenal hyperplasia is the most common cause in infancy.
2) acquired etiologies: most important causes are:
1. Addison disease
2. infec: Most frequent infection is meningococcemia.
3. drugs: Ketoconazole inhibit adrenal enzymes
Rifamp & anticonvulsants (ex. Phenytoin) ↓effectiveness & bioavailability of corticosteroid by inducing steroid- metabolizing enzymes in the liver.
Mitotane (used in treatment of adrenal carcinoma & refractory Cushing syndrome)
Most important causes of Secondary adrenal insufficiency are:
1. ACTH deficiency
2. abrupt cessation of corticosteroids ex. in pt w` leukemia


Addison disease
Definition: is an autoimm destruction of adrenal glands.
Clinical features:
- ↓cortisol hypoglycemia
- Cortisol deficiency stimulate hypothalamus & pituitary glands to ↑secretion of ACTH which have cross-reaction with melanocyte stimulating hormone hyperpigmentation which may be more prominent in skin creases, mucosa, & scars.
- Aldosteron deficiency ↓resorption of Na+ in distal nephron hyponatremia hypovolemia Hypotension.
- aldosteron deficiency↓K+ excretion in distal nephronhyperkalemia
- ↓catecholamine (ex. epinephrine) ↓inotropic & pressor effect which initially manifested as orthostatic Hypotension.
Rx:
- Rx must be immediate & vigorous.
- fluid resuscitation: i.v 5% glucose in 0.9% saline solution.
- Rx of severe hyperkalemia (if occur) : i.v Ca &/or sodium bicar, intrarectal K+ binding resin (kayexalate), or i.v glucose & insulin.
- Hydrocortisone sodium succinate 10 mg for infant 25 toddlers i.v at 6 hr intervals 50 older child. 100 adolescents
- chronic replacement therapy for their cortisol & aldosteron deficiency.
Hydrocortisone orally 10 mg/m2/day ÷3 or Prednisolone ÷2
During stress ex. infec or operation, the dose of H.C s.b ↑ 3 folds.
glucocorticoid overdose obesity, short stature, osteoporosis.
- if aldosterone defiency is present, fludrocortisones orally 0.3 mg/day ( which is mineralocorticoid)
Fludrocortisones overdose tachycardia, Hypertension, hypokalemia.

Congenital adrenal hyperplasia CAH

is a group of autosomal recessive inborn errors of metabolism in adrenal gland steroidogenic pathways that produce mineralocorticoids, glucocorticoids, & androgens.
Rx according to the type of CAH:
1. glucocorticoid replacement : H.C 20 mg/m2/day orally ÷3. Rx must be continued indefinitely (for life).
2. mineralocort. Replacement:
Fludrocortisones 0.3 mg/day ÷2 for infants & 0.1 mg/day ÷2 for child
3. surgical Mx of ambiguous genitalia between 4-12 m age
4. incomplete virilized genetic male may benefit from several injections of testosterone early in infancy to ↑size of the phallus & may require testosterone replacement at puberty.
Female require estrogen replacement at puberty
Adrenocortical hyperfunction
ex. CAH , tumor, Cushing synd


Cushing syndrom
Caused by abnormally high blood levels of cortisol or other glucocorticoids. the circadian rhythm of cortisol secretion is lost & the cortisol level at day and night a` comparable. But the most com cause of Cushing synd is exogenous corticotrophin.
Clinical features:
- moon face (the face is round, prominent cheeks, flushed appearance)
- generalized obesity.
- impaired growth with length falling below 3rd percentile
- Hypertension
- ↑susceptibility to infections
- purplish striae on the hip, abdomen and thighs
- delay pubertal development, amenorrhea.
- hyperglycemia may progress to frank diabetes.
- osteoporosis may pathologic fractures
- difference between obesity & Cushing synd clinically:
cushing
obesity

short

Accepted
hight
Egg on stick, buffalo hump
Generalized obesity
Shape of patient
delay
Advance
bone age
osteoporosis
increase
bone density


Rx: according to the cause:
- Transsphenoidal pit microsurgery is the Rx of choice.
Inhibitors of adrenal steroidogenesis (metyrapone, ketoconazole, aminoglutethimide) used pre operative to normalize circulating cortisol level.
- Cyproheptadine (centrally acting serotonin antagonist) block ACTH release, but rarely used in child.
- if the pituitary adenoma not respond to Rx or if there is ACTH secretion by ectopic metastatic tumor; adrenal gland. should be removed
Post op replacement therapy with corticosteroid is required.

Pheochromocytoma

- is a chatecholamine-secreting tumor, arises from chromaffin cells.

الدكتور

صلاح مهدي فرحان
اختصاصي طب الاطفال والخدج
مستشفى الحسين (ع) التخصصي للاطفال