Endocrine series Part 1

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Endocrine series Part 1

  1. 1. ENDOCRINE SERIES AKSHAT JAIN MD FAAP MOUNT SINAI SCHOOL OF MEDICINE New York
  2. 2. Hypothalamus and Pituitary Axis
  3. 3. Hypothalamus and Pituitary <ul><li>The hypothalamus-pituitary unit is the most dominant portion of the entire endocrine system. </li></ul><ul><li>The output of the hypothalamus-pituitary unit regulates the function of the thyroid, adrenal and reproductive glands and also controls somatic growth, lactation, milk secretion and water metabolism. </li></ul>
  4. 4. Hypothalamus and pituitary gland
  5. 5. Posterior Pituitary: neurohypophysis <ul><li>Posterior pituitary : an outgrowth of the hypothalamus composed of neural tissue. </li></ul><ul><li>Hypothalamic neurons pass through the neural stalk and end in the posterior pituitary. </li></ul><ul><li>The upper portion of the neural stalk extends into the hypothalamus and is called the median eminence . </li></ul>
  6. 6. Hypothalamus and posterior pituitary Secrete oxytocin and vasopressin directly into capillaries in the posterior lobe
  7. 7. Anterior pituitary: adenohypophysis <ul><li>Anterior pituitary : connected to the hypothalamus by the superior hypophyseal artery. </li></ul><ul><li>The anterior pituitary produces six peptide hormones: </li></ul><ul><li>Prolactin, </li></ul><ul><li>(GH), </li></ul><ul><li>(TSH), </li></ul><ul><li>(ACTH), </li></ul><ul><li>(FSH), </li></ul><ul><li>(LH). </li></ul>
  8. 8. Hypothalamus and anterior pituitary
  9. 9. Regulation of Hypothalamus Reituclar activating substance Thalamus neocortex Limbic system Optical system Heat regulation (temperature) Energy regulation (hunger, BMI) Autonomic regulation (blood pressure etc) Water balance (blood volume, intake--thirst, output—urine volume) Metabolic rate, stress response, growth, reproduction, lactation) Sleep/wake pain Emotion, fright, rage, smell vision Anterior pituitary hormones posterior pituitary hormones
  10. 10. Hypothalamic releasing factors for anterior pituitary hormones <ul><li>Travel to adenohypophysis via hypophyseal-portal circulation </li></ul><ul><li>Travel to specific cells in anterior pituitary to stimulate synthesis and secretion of trophic hormones </li></ul>
  11. 11. Hypothalamic releasing hormones Hypothalamic releasing hormone Effect on pituitary Corticotropin releasing hormone (CRH) Stimulates ACTH secretion Thyrotropin releasing hormone (TRH) Stimulates TSH and Prolactin secretion Growth hormone releasing hormone (GHRH) Stimulates GH secretion Somatostatin Inhibits GH (and other hormone) secretion Gonadotropin releasing hormone (GnRH) a.k.a LHRH Stimulates LH and FSH secretion Prolactin releasing hormone (PRH) Stimulates PRL secretion Prolactin inhibiting hormone (dopamine) Inhibits PRL secretion
  12. 12. Characteristics of hypothalamic r.H.’s <ul><li>Secretion in pulses </li></ul><ul><li>Stimulate release of stored pituitary hormones </li></ul><ul><li>Stimulate synthesis of pituitary hormones </li></ul><ul><li>Stimulates hyperplasia and hypertrophy of target cells </li></ul><ul><li>Regulates its own receptor </li></ul>
  13. 13. Anterior pituitary cells and hormones Breasts PRL 10-15% Lactotroph All tissues, liver, gonads GH 40-50% Somatotroph Gonads LH, FSH 10-15% Gonadotroph Thyroid gland TSH 3-5% Thyrotroph Adrenal gland Adipocytes Melanocytes ACTH 15-20% Corticotroph Target Product Pituitary population Cell type
  14. 14. Anterior pituitary hormones
  15. 15. SHORT STATURE and GROWTH HORMONE
  16. 16. CASE VIGNETTE <ul><li>A 10 year old girl presents to your clinic for evaluation of short stature. Parents report that she has always been the shortest girl in her class, but they have become concerned because the patient's 8 year old sister is now the same height as she is. </li></ul><ul><li>The patient has not yet attained menarche and her mother reports no breast development . </li></ul><ul><li>She has been well with no chronic medical problems, no hospitalizations, and no surgeries. She lives with her mother, father, and sister and she is currently has good school performance. </li></ul>
  17. 17. <ul><li>A student in the fifth class. On further history, you find that your patient was 43 cm (17 inches) long at term (average is 49.5 cm, 19.5 inches). </li></ul><ul><li>Family HX - Her mother is 173 cm (5'8&quot;) and weighs 68 kg (150 pounds). She had menarche at age 12. The patient's father is 185 cm (6'1&quot;) and weighs 95 kg (210 pounds). He started shaving at age 15. There is no family history of any medical problems. </li></ul><ul><li>Exam: VS T 37.0, P 90, R 18, BP 100/60. </li></ul><ul><li>Height 120 cm (<5%), weight 23 kg (slightly <5%). </li></ul><ul><li>She is an alert, small appearing girl who is in no apparent distress. HEENT exam is normal. Neck is supple with webbed appearance . Heart regular rate, no murmurs. Lungs are clear. Abdomen is soft without masses. Tanner 1 breasts with wide-spaced nipples are evident. The carrying angle is increased . Tanner 1 pubic hair is noted. </li></ul><ul><li>Her growth chart is reviewed which demonstrates an average growth velocity of 3 cm per year. </li></ul>
  18. 18. <ul><li>She is sent for a bone age that is read by the pediatric radiologist as 8 years and 6 months. </li></ul><ul><li>CBC, ESR, TFT's, UA, and serum electrolytes are normal. </li></ul><ul><li>Chromosomes are obtained </li></ul>
  19. 21. ICP Model Infancy Childhood Puberty Nutrition Thyroxin GH Sex Steroids
  20. 22. <ul><li>Short stature is defined as standing height (or supine length) more than 2 SD below the mean (or below the 2.5 percentile) for gender.   </li></ul><ul><li>However, short stature optimally is defined relative to the genetic endowment of the individual and, particularly, the mid-parental height (MPH). A child’s predicted adult height should fall within 10 cm of his/her parents’ MPH. </li></ul>
  21. 23. CONCEPT OF MPH <ul><li>Boys: [father's height in cm + (mother's height in cm + 13 cm)]/2 </li></ul><ul><li>Girls: [(father's height in cm – 13 cm) + mother's height in cm]/2 </li></ul>
  22. 24. Concept of GROWTH VELOCITY Boys: 10 to 14 cm (4 to 6 in) Girls: 8 to 12 cm (3 to 5 in) Pubertal growth spurt 5 to 5.5 cm (2 to 2.2 in) Prepubertal nadir 6 to 7 cm (2 to 3 in) Fourth year 10 to 14 cm (4 to 6 in) Second year 23 to 27 cm (9 to 11 in) First year 60 to 100 cm (24 to 40 in) In utero Growth velocity per year Life stage
  23. 25. <ul><li>Girls usually continue to grow until a bone age (BA) of about 14 yrs and boys stop growing after a BA of 16. </li></ul>
  24. 26. Concept of GROWTH CHANNEL <ul><li>From 6-18 months, many children move up or down on their growth percentiles, but by 24 months , most children find “their” growth channel and stay on the same percentile. </li></ul>
  25. 27. Concept of Weight for Height <ul><li>It is also important to look at a child’s weight in relation to height. </li></ul><ul><li>Overweight children are usually tall because of an accelerated growth rate. </li></ul><ul><li>Child who is short and overweight should be evaluated - ANY GUESSES ? </li></ul>
  26. 28. Concept of Bone AGE <ul><li>Provides an estimate of a child's skeletal maturation by assessing the ossification of the epiphyseal centers. </li></ul><ul><li>Accurately predicts adult height , >6 YRS </li></ul><ul><li>Bone age is considered delayed if it is two standard deviations below the chronologic age. </li></ul><ul><li>Familial short stature, bone age is normal for chronologic age </li></ul><ul><li>Constitutional delay of growth and puberty, bone age corresponds with height age and is typically delayed by two standard deviations. </li></ul><ul><li>Pathologic short stature, bone age is severely delayed (usually more than two standard deviations), </li></ul>
  27. 29. Causes of short stature <ul><li>Familial short stature  (also referred to as genetic or idiopathic short stature (ISS) </li></ul><ul><li>Constitutional delay of growth and development (CDGD) </li></ul><ul><li>Pathological Short Stature – </li></ul><ul><li>a. HPA axis abnormality </li></ul><ul><li>b. Chronic debilitating conditions </li></ul>
  28. 30. Familial Short Stature
  29. 31. Familial short stature Most parents with short stature have short children. These children have a Normal growth velocity and their growth curves run parallel to the normal growth curves. A Short as adults, with a similar height to their parents.
  30. 35. Constitutional delay of growth and development:   <ul><li>These children also have a normal growth velocity but will have delayed puberty , and possibly a prolonged slowdown in growth that occurs just before puberty. </li></ul><ul><li>Their delayed BA means ?. </li></ul><ul><li>Shorter than their peers throughout childhood but subsequently catching up to a normal final adult height. </li></ul><ul><li>Testestosterone VS GH dilemma . </li></ul>
  31. 36. GROWTH HORMONE DEFICIENCY <ul><li>These include children with low serum IGF-1 and IGF-BP3, </li></ul><ul><li>midline defects, abnormalities of other pituitary or hypothalamic function, or </li></ul><ul><li>simply a clear deviation from their normal growth pattern. </li></ul><ul><li>GHD is diagnosed only by abnormal GH stimulation tests which are done in a same-day admission. Documented GHD must be treated with GH. </li></ul>
  32. 37. <ul><li>Another recent FDA approval for GH is small for gestational age (SGA). Most SGA babies “catch-up” by 6 months of age. However, about 10% of SGA infants will remain below the 3rd percentile. If they have not caught up by age 2-3 years they should be referred to a pediatric endocrinologist. </li></ul>
  33. 39. Abnormal Growth Findings Suggesting the Need for Referral Bone age: advanced or delayed by more than two standard deviations Multiple syndromic or dysmorphic features: abnormal facies, midline defects, body disproportions Genetic potential: projected height varies from midparental height by more than 5 cm (2 in) Growth velocity: decreased or accelerated growth velocity for age Height: growth less than the 3rd percentile or greater than the 95th percentile for height
  34. 40. SHOX

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