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Adrenal gland new


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Adrenal gland new

  1. 1. ADRENAL GLAND • Corticosteroid hormones(cortisol an dihydroxycortisol) - to help control the body's use of fats, proteins, and carbohydrates. • Aldosterone - inhibits the level of sodium excreted into the urine, and maintains blood volume and blood pressure. • Androgenic steroids (androgen hormones) - hormones that have an effect on the development of male characteristics.
  2. 2. CONT……… • Epinephrine (adrenaline) - increases the heart rate and force of heart contractions. • Norepinephrine (noradrenaline) - this hormone has little effect on smooth muscle, metabolic processes, and cardiac output, but has strong vasoconstrictive effects .
  3. 3. CORTISOL • produced by the zona fasciculata of the adrenal cortex. • Its primary functions are to increase blood sugar through gluconeogenesis • A cortisol level lower than 6 micrograms per deciliter of blood may indicate Addison's disease or hypopituitarism. • Cortisol levels above 23 micrograms per deciliter can be a sign of adrenal tumor or Cushing's syndrome.
  4. 4. ALDOSTERONE Synthesized and released into bloodstream by zona glomerulosa of the adrenal gland Average daily production is 0.1 to 0.7 μml (50 to 250 μg) with normal salt intake. Inactivated in liver by conjugation with glucuronic acid or sulfuric acid Secretion is regulated by renin-angiotensin system (main regulator), serum potassium concentration and ACTH levels .Decrease in effective circulating blood volume increases aldosterone via renin-angiotensin axis Increase in serum potassium increases aldosterone levels ACTH plays a minor role in regulation of aldosterone synthesis Aldosterone secretion in healthy subjects is increased by low- salt diet (< 2 gm/day), stress, upright posture and diuretic therapy, and is decreased by high salt diet or lying supine (lying down with face up)
  5. 5. Major regulator of effective circulating blood volume ● Increases renal reabsorption of sodium and water to maintain blood pressure and tonicity ● Acts through mineralocorticoid receptors in renal cortical collecting ducts ● Also increases urinary excretion of potassium and hydrogen ions ● Recently discovered to have an effect on endothelium and coronary relaxatio
  6. 6. Plasma aldosterone - supine position and normal sodium diet: 209 ng/dl (55-250 pmol/L) ● Plasma aldosterone - upright position (standing/seated for at least 2 hr) and normal sodium diet: 2-5x supine value ● Urine aldosterone: 5-20 μmg/24 hr (14-56 nmol/24 hr) ● Conversion factor: multiply by 0.0277 to convert from ng/dl to nmol/L
  7. 7. High values: primary hyperaldosteronism, aldosterone secreting adrenal tumor, idiopathic adrenal hyperaldosteronism Low values: adrenal insufficiency, congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency
  8. 8. ANDROGENS Includes androstenedione and DHEAS (dehydroepiandrosterone) Normal plasma levels of: a)DHEAS is 4.5-18.8 mumol/l In men and 3.5 - 17.8 mumol/l in women b)Androstenedione is 2.1 -7.7 in men and 3.3 - 9.9 in women Elevated levels of this hormones lead to masculinization
  9. 9. Dopamines • Include norepinephrine (decapeptide) and epinephrine (octapeptide) • About half of plasma dopamines produced in the adrenal medulla • The plasma free dopamine level is about 35 pg/mL (0.23 nmol/L) • Increased level is due to factors such as hypoglycemia ,surgery,ketoacidosis ,exercise and myocardial infarction
  10. 10. • Relative adrenal insufficiency is present when adrenal response is inadequate for the stress situation-highest levels of baseline cortisol -but do not respond to the ACTH stimulation test absolute adrenal insufficiency is characterized by low levels of baseline cortisol and by non-response to the ACTH stimulation test.
  11. 11. Functional tests and their medical Importance 1.Random cortisol level Test • Cortisol’s normal diurnal variation is often lost in critically ill patients, so cortisol can be measured at any time during stress. • 2.The ACTH stimulation test • It is performed to evaluate adrenal gland response and reserve, i.e., it is important to detect relative adrenal insufficiency. During the standard ACTH stimulation test, cortisol is measured before and then 30 and 60 minutes after cosyntropin (Cortrosyn; ACTH 1-24) 250 mg is given intravenously or intramuscularly. The test can be performed at any time of day with similar maximum cortisol levels. • may not detect partial adrenal insufficiency in patients with hypothalamic or pituitary disorders,
  12. 12. • 3. Low-dose test • The dose of cosyntropin used in the standard ACTH stimulation test—250 μg—is a large overdose. For this reason and to improve the test’s sensitivity in detecting partial secondary or tertiary adrenal insufficiency, the low- dose ACTH stimulation test has been adopted, which uses cosyntropin 1 mg intravenously. The low-dose test is more sensitive in detecting partial adrenal insufficiency in critically ill patients. • The cortisol level at 30 minutes during the standard ACTH stimulation test is similar to the result during the low dose test. For this reason, the standard test is normally used, with a cortisol threshold of 20 mg/dL at 30 minutes.
  13. 13. 4. Delta 9” as a cutoff value • The “delta” value during the ACTH stimulation test is the difference between the baseline and the maximum cortisol value at either 30 or 60 minutes. • Delta 9 (9 mg/mL) is the cutoff for diagnosing relative or functional adrenal insufficiency in patients with septic shock in an intensive care unit. • The delta value is a measure of adrenal reserve
  14. 14. 5. Free cortisol test • About 70% of circulating cortisol is tightly bound to cortisol-binding globulin (CBG), and about 10% to 20% is loosely bound to albumin. • That only free cortisol is biologically active. Free cortisol levels in thus dependeds on the serum albumin level. • Patients with hypoalbuminemia (albumin levels ≤2.5 g/dL) have significantly lower basal and stimulated total cortisol levels during the ACTH stimulation test, and nearly 40% of them have a stimulated total cortisol level ≤18.5 μg/dL. • In critically ill patients with hypoalbuminemia , total serum cortisol may be a poor indicator of glucocorticoid activity
  15. 15. The metyrapone • The metyrapone test was developed to evaluate pituitary reserve • Metyrapone inhibits enzyme P450C11, which converts 11- deoxycortisol (compound S) into cortisol, consequently reducing serum levels of cortisol and increasing 11-deoxycortisol levels. • Reduction in serum cortisol stimulates release of ACTH by feedback, acting at a hypothalamic-pituitary level. • Adequate adrenal production occurs when compound S is higher than 7.0 μg/dL, independent of cortisol value. • Required waiting time for its execution is at least 8 hours between administration of metyrapone and serum dosages.