Endocrinology

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Endocrinology

• Edward Buckingham, M.D.
• Francis Quinn, M.D. F.A.C.S.

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Pituitary - Embryology and Anatomy

• posterior pituitary- neurohypophysis
• outpouching floor 3rd ventricle
• nervous connection to hypothalamus
• octapeptides-oxytocin, vasopressin (ADH)
• anterior pituitary-adenohypophysis
• Rathkes pouch
• no direct nerve supply
• chemical hypophyseal-portal system
• ACTH, TSH, GH, PRL, FSH, LH

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Pituitary - Embryology and Anatomy
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Pituitary - Sella tercica, sphenoid bone
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Pituitary - Relation to sphenoid sinus
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Pituitary - Soft tissue boundaries
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Pituitary - Vasculature
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Pituitary - Embryology and Anatomy
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Pituitary - Embryology and Anatomy
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Pituitary - antidiuretic hormone (ADH)
(vasopressin)

• CNS osmoreceptors supraoptic, periventricular
  nuclei hypothalamus
• plasma osmolality changes
• baroreceptors, aortic arch, carotid sinus, left
  atrium
• CN IX, X
• renal action
• ADH increases H2O permiability of DCT and CD

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Pituitary - ACTH

• proopiomelanocortin precursor
• melanotropins, lipotropins and B-endorphin
• circadian rhythm peaks am,
• stimulus, CRF- stress, hypoglycemia,
• CRF-feed back from glucocorticoids in circulation
• action- adrenal cortex secrete glucocorticoids,
  lesser aldosterone

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Pituitary - TSH

• glycoprotein hormone, thrytopic cells, level
  constant
• stimulus, TRH
• feedback free T3
• c-AMP mediated
• action-early increased formation of colloid,
  uptake of iodine, formation of TH
• action-late increased volume and number of cells

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Pituitary - GH

• via somatomedins promotes longitudinal growth
• anabolic protein metabolism, lipolytic,
  stimulates insulin release, decreases peripheral
  tissue utilization of glucose

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Pituitary - Prolactin

• acts on prepared mammary tissue to initiate and
  maintain lactation

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Pituitary - FSH, LH

• Kallmanns syndrome- maldevelopement olfactory
  lobes, related hypothalamic lesions, hyposmia,
  anosmia, isolated Gn-RH deficiency

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Pituitary - Diabetes Insipidus

• partial or complete absence of vasopressin
• tumor, inflammation, granuloma, trauma, vascular

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Pituitary - Diabetes Insipidus

• clinical features
• polyuria- 3-15 L/day 4-5 L common, SG lt 1.005,
  urine osmolality lt200 mOsm/kg, plasma osmolality
  gt 287 mOsm/kg
• polydipsia- compensatory mechanism, hypothalamic
  thirst center destruction disastrous
• associated features- visual field loss, optic
  atrophy, papilledema, other pituitary hormone
  abnormalities

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Pituitary - Diabetes Insipidus

• treatment
• acute- liberal fluid replacement, short-acting
  aqueous vasopressin
• chronic- dDAVP intranasally BID

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Pituitary - SIADH

• continued secretion of antidiuretic hormone
  despite hypotonicity
• secreted by pituitary or ectopic source

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Pituitary - SIADH

• clinical features
• fatigue, muscle weakness, dizziness, behavioral
  changes, drowsiness, Na lt 120 stupor,
  convulsions, coma
• urine osmolality not maximally dilute despite
  hypotonicity

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Pituitary - SIADH

• diagnostic criteria
• hyptonicity of plasma
• hyponatremia
• less than max dilute urine
• naturesis
• exclusion of other causes

• treatment
• water restriction 600-800 ml/day
• demeclocycline 900-1200 mg/day- blocks
  vasopressin at DCT
• hypertonic saline if sodium lt 115 mEq/L

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Pituitary - Tumor classes

• Class 1 - microadenomas lt 10mm diameter
• Class 2 - macroadenomas gt10 mm diameter
• Class 3 - part of sellar floor involved
• Class 4 - all of the floor destroyed

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Parathyroid- Embryology and Anatomy

• third and fourth branchial pouches
• third migrates with thymus
• aberrant in 15 to 20
• ICA to AP window ant or post to arch
• usually 4 glands may be 6 or more

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Parathyroid- Ectopic glands
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Parathyroid- Blood supply

• inferior/superior parathyroid arteries
• branches of inferior thyroid artery
• occas. superior from sup. thyroid artery

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Parathyroid- Calcium metabolism

• actions of PTH
• increases serum calcium level
• increases urine phosphate
• increases bone osteoclast and osteoblast activity
• increases bicarbonate excretion by kidney
• increase GI calcium and phosphate absorption
  through Vit D
• increases conversion of 25-OH Vit D to 1,25
  di-OHVit D

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Parathyroid- Calcium metabolism

• calcitonin
• parafollicular cells response to increased Ca
• inhibit bone resorption, increase phos excretion
  by kidney
• vitamin D
• absorbed through skin or GI tract
• liver 25 OH
• kidney 1,25 OH most active form
• increases calcium and phosphate absorption and
  retention

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Parathyroid - Hypercalcemia
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Parathyroid - Assoc. conditions
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Parathyroid- Hypercalcemia

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Parathyroid - laboratory evaluation
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Parathyroid - definitions

• primary hyperparathyroidism
• single adenoma 85, 12 hyperplastic glands, 3
  multiple adenomas
• secondary hyperparathyroidism
• hyperplastic glands
• malfunction of another organ system
• usually renal failure

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Parathyroid - definitions

• tertiary hyperparathyroidism
• similar to secondary
• PTH production now autonomous
• renal transplant

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Parathyroid - hyperparathyroidism

• Laboratory values
• low serum phosphorus (lt2.5 mg/dL)
• hyperchloremia (gt107 mEq/L)
• alkaline phosphatase elevated in 10
• indicates osteitis fibrosis cystica
• subperiosteal bone resorption

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Hyperparathyroidism - surgery

• asymptomatic hyperparathyroidism
• Kaplan
• compared metabolic benefits
• 6 pt asymptomatic with 7 symptomatic before and
  after surgery
• concluded asymptomatic received same benefits

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Hyperparathyroidism - surgery

• Other pros
• postmenapausal women
• Cogan psychologic function and EEG improved
• avoid hypercalcemia if sick or dehydrated
• cost effective
• surgery indicated
• hypertension, mildly reduced creatinine
  clearance, increased urine calcium, decreased
  bone density, clinical symptoms

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Thyroid - Embryology and Anatomy

• embryology
• pharyngeal floor, foramen cecum
• decent with parathyroids
• lateral to TE groove
• assoc. with RLN

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Thyroid - Embryology and Anatomy

• vasculature
• arterial
• sup. thryroid artery ECA
• inf. thyroid artery TCT
• venous
• superior and middle- IJV
• inferior BCV
• lymphatics
• pretracheal, paratracheal

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Thyroid - Physiology

• hormonogenesis
• trapping - iodine oxidized
• organification - tyrosyl incorporation
• MIT, DIT, T3, T4
• secretion
• 95.5 bound. 0.5 free biologically active
• TBG primarily, prealbumin, albumin
• T4 gt T3 liver and kidney

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Thyroid - Physiology

• hormonogenesis
• inhibited by
• renal, hepatic disease
• acute or chronic illness
• drugs- propylthiouracil, glucocorticoids,
  propranolol, iopanoic acid
• reverse T3
• regulation
• feedback of free T3 on TRH and TSH
• action
• metabolic rate, thermogenesis

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Thyroid - TFTs

• T4 radioimmunoassay
• measures bound and unbound hormone
• T3RU
• determines TBG capacity
• radiolabeled T3 given
• bound to TBG open sites
• resin given 25-35 normally binds to resin
• increased TBG decreased T3RU

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Thyroid - TFTs

• FTI
• product of T3RU and T4
• good initial determination of hyper or hypo
  thyroidism
• T3 radioimmunoassay
• reflects peripheral metabolism not thyroid
  function
• T3 thyrotoxicosis

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Thyroid - TFTs

• TSH
• hypothyroidism
• replacement therapy
• euthyroid goiters

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Thyroid imaging

• thyroid scans
• radioactive isotopes of iodine
• one month to clear contrast agents
• indications
• hot and cold nodules
• metastatic thyroid cancer
• ectopic tissue
• Hashimotos

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Thyroid imaging

• ultrasonography
• solid vs. cystic
• FNA
• suppression

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Thyroid - Hyperthyoidism
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Thyroid - Hypofunction
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Adrenal Gland

• cortex
• zona glomerulosa
• mineralocorticoids- aldosterone
• zona fasciculata
• glucocorticoids- cortisol
• zona reticularis
• androgens- estrogen, progesterone, testosterone
• medulla
• norepinephrine, epinephrine

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Adrenal Gland - Physiology

• zona glomerulosa
• renin JG cell
• respond to Na, and volume
• angiotensinogen gt angiotensin I
• angiotnsin I gt angiotensin II by ACE
• angiotensin II potent pressor gt aldosterone
• hyperkalemia promotes independently
• hypokalemia inhibits
• ACTH

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Adrenal Gland - Physiology

• zona fasciculata
• ACTH as discussed
• cortisol actions
• zona reticularis
• ACTH controls
• no feedback
• adrenarche

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Hyperadrenocorticism

• cushings sydndrome
• 3rd - 6th decade, 4 to1 females
• causes
• pharmocologic
• pituitary adenoma 75-90
• adrenal adenoma, carcinoma
• ectopic ACTH
• treatment based on cause

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Adrenocortical insufficiency

• primary causes, ie. Addisons disease
• autoimmune disease, tumors, infection,
  hemorrhage, metabolic failure,
• secondary causes
• hypopituitarism, suppression exogenous steroids

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Adrenocortical insufficiency

• symptoms, signs
• fatigability, weakness, anorexia, nausea, weight
  loss, hyperpigmentation, hypotension, women loss
  of axillary and pubic hair
• can lead to severe volume depletion and shock
• treatment
• glucocorticoid replacement, mineralocorticoid
  replacement

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Overproduction of aldosterone

• primary causes, ie. Conns syndrome
• adenoma, nodular hyperplasia zona glomerulosa
• secondary
• cirrhosis, ascites, nephrotic syndrome, diuretic
  use
• symptoms, signs
• headache, hypokalemia causing muscle weakness,
  nocturnal polyuria, hand cramping

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Overproduction of aldosterone

• treatment
• surgical for adenoma
• medical for hyperplasia with sprionolactone

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Pancreas

• alpha cells- glucagon
• beta cells- insulin
• stimulus
• glucose, amino acids, glucagon, GI hormones,
  vagal nerve
• inhibition
• B-adrenergic blockers, sympathomimetics,
  somatostatin

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Diabetes
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Surgical care

• 120-250 mg/dL
• 1-2 hr checks
• 3 g/kg/day prevent catabolism and lipolysis
• 5 dextrose at 100 ml/hr

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Ketoacidosis

• ketone bodies metabolic acidosis-lipolysis
• IV insulin 12-20 u bolus
• .05 to 0.1 u/kg/hr
• IVF - 0.9 NS
• glucose approx. 200 add dextrose
• potassium electrolytes as needed
• monitor anion gap for endpoint

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Hyperosmotic nonketotic coma

• similar to above
• disagreement isotonic/hypotonic saline
• severe dehydration
• watch electrolytes closely

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Case Presentation

• 45 year old with craniopharyngeoma now 24 hrs
  post-op from a transphenoidal approach to tumor
  excision
• Nurse notifies you patient urinated 3L over the
  last 8 hrs and 5L over the last 16 hrs

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Case Presentation

• PE
• The patient is slightly somnolent, but arousable,
  oriented to person and place, but not to time or
  situation, this is new over last 4-5 hrs
• No polydipsia
• Neuro-exam is otherwise normal
• Labs
• CBC, Chem 7, plasma osmolality pending,
  urinalysis SG - 1.003, urine osmolality 185
  mOsm/kg.

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Case Presentation

• CT Head
• post-operative changes, otherwise normal
• Labs
• WBC 10.5, HGB 14.5, HCT 45.2, Plt 567K,
• Na-162, K-5.4, Cl-110, CO2-18, BUN-45, Cr-.76,
  Glucose 120
• Osmolality - 300 mOsm/kg

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Case Presentation

• Diagnosis
• Diabetes insipidus with injury to hypothalamic
  thirst center
• Therapy
• Fluid boluses with isotonic saline
• aquous vasopressin