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Flashcards in Endocrine Deck (56)
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1

Preop assessment components?

  • Dx of proposed procedure
  • Medical Hx –Review of systems
  • Current medications- herbs, minerals, PRn meds
  • Allergies
  • Physical exam
  • Airway Exam
  • Lab findings
  • Surgical Hx – previous complications
  • ASA status
  • Consent

2

What is the thyroid gland? Role?

Gland:

  • Two lobes connected by an isthmus
  • 4 parathyroid glands located posteriorly
  • Superior larngeal nerve external branch and RLN (recurrent laryngeal nerve) transverses the boarder
  • Produces – T4 (thyroxine - prohormone) and T3 (triiodothyronine - active)

Role:

  • Cell differentiation
  • Organogenesis
  • Thermogenesis
  • Metabolic homeostasis

3

What is the HPA axis for thyroid hormone release?

  • Homeostasis disturbed, low T3/T4 detected at hypothalamus or low body temperature
  • hypothalamus releases TRH
  • Goes to anterior pituitary to release TSH
  • TSH goes to thyroid gland to release T3/T4
  • Normal homeostasis maintained with normal T3/T4 and normal body temp

4

Difference between T3/T4?

T3

  • Active
  • 30 mcg/day
  • 10% by gland (80% kidney/liver)- peripheral conversion in kidney and liver
  • 3-4x’s as potent
  • 1 day

T4

  • Inactive
  • 80 mcg/day- 2-3 x the amount of T3
  • Solely by gland
  • Potent
  • 7 days- keep in mind people can still have s/s hyperthyroidism up to one week after surgery

5

Causes of hyperthyroidism?

  • Primary
    • Graves disease (autoimmune disorder)- tricks receptor to thinking it's TSH
    • Toxic adenoma (gland overgrowth from lack of iodine)
    • Multinodular goiter (genetics/lack of iodine)- Similar to toxic adenoms but can have genetic component too
  • Secondary- something besides the thyroid causing excess T3/T4 to be made
    • TSH secreting pituitary adenoma
  • Tertiary
    • Amiodarone toxicity

6

S/S Hyperthyroidism?

  • Neuro
    • Anxiety & fatigue
  • Ophthalmology
    • Exophthalmos
  • CV
    • HTN, tachycardia, atrial fibrillation, & increased CO
  • GI
    • Diarrhea and weight loss
  • Renal
    • Hypercalciuria
  • MS
    • Muscle weakness
  • Goiter
    • Weight loss

7

What with Free T4, free T3 and TSH be on labs for graves disease, multinodular goiter, and toxic nodules?

  • Graves Free T4/T3 elevated, TSH down; TSH antibody present; RAIU diffuse uptake
  • Mulinodular T4/T3 elevated, TSH down; RAIU areas of increased and decreased uptake
  • Toxic nodule T4/T3 elevated; TSH down; RAIU focal uptake

8

Potential treatment hyperthyroidism?

  • Anti-thyroid drugs (Inhibits thyroid hormone synthesis)
    • Methimazole or Propylthiouracil (PTU) – takes 6 -8 weeks
  • Iodine inhibiting drugs (prevent hormone release)
    • Potassium iodine 
  • Steroids (prevents conversion of T4 to T3/decrease secretion)
    • Decadron 6 mg
    • Hydrocortisone 100 mg 
  • Beta blockers (block adrenergic stimulation)
    • Propranolol (prevents conversion of T4 to T3)
    • Esmolol- blocks sympathetic, rapid on/off

9

Anesthesia implications for hyperthyroidism

  • most important goal is to make the patient euthyroid before surgery-can take 6-8 weeks
  • Adequate depth of anesthesia to limit SNS activation
  • Avoid medications that stimulate SNS
    • Ketamine, pancuronium, ephedrine, or anticholinergics
  • HR goal: < 85 bpm
  • Excellent airway exam
    • X-ray or CT to evaluate airway compression
  • Regional is excellent alternative (avoid adding epinephrine to solution)- avoid epi more theoretical risk with systemic absorption 
  • Eye protection
  • Temperature monitoring – may need to cool

10

S/S and differntial for thyroid storm?

Thyroid Storm

  • Life-threatening emergency
  • Response to stress
  • Hyperpyrexia
  • Tachycardia
  • Myocardia ischemia
  • Alterations in consciousness- difficult to see periop

Differential

  • Light anesthesia
  • Pheochromocytoma
  • Neuroleptic malignant syndrome
  • Malignant hyperthermia 

11

Treatment thyroid storm

  • IV fluids
  • Propylthiouracil via NGT
  • Sodium iodide
  • Hydrocortisone
  • Propranolol/esmolol
  • Cooling blanket
  • Acetaminophen
  • Meperidine
  • Digoxin

12

Primary and secondary causes for hypothyroidism?

Primary

  • Hashimoto thyroiditis (autoimmune)
  • Surgical removal of thyroid
  • Severe iodine depletion
  • Neck radiation

Secondary

  • Pituitary disfunction
  • Hypothalamic dysfunction

13

s/s hypothyroidism?

  • Neuro
    • Fatigue, memory impairment, depression, or emotional liability
  • CV
    • Bradycardia, HTN w/ narrowed pulse pressure, or pericardial effusion
    • Low voltage EKG 
    • Prolonged PR, QRS & QT interval
  • Resp
    • Need thyroid hormone for surfactant production
    • Decreased response to hypoxia and hypercarbia
  • Optho
    • Blurred vision
  • Renal
    • SIADH – water retention
  • Musculoskeletal
    • Hyporeflexia
    • Large tongue
    • Cold intolerance
    • Goiter

14

Lab diagnosis of hypothyroidism?

  • Primary hypothyroidism- TSH elevated, T4 low
  • Subclinical TSH elevated; T4 normal
  • Secondary TSH normal or low; T4 low

15

Treatment for hypothyroidism?

 

  • Hormone replacement with Synthroid
  • Be careful with replacement – patient with CAD may not tolerate sudden increase in heart rate 

16

Anesthesia considerations with hypothyroidism?

  • Little reason to postpone elective surgery with mild/moderate hypothyroidism
  • Surgery should be postponed with severe hypothryoridism
  • Maintain medications up to morning of surgery
  • Cardiovascular changes are often the earliest changes
  • Get EKG
  • Cortisol deficiency is possible – atrophy of gland
    • May need replacement therapy- need cortisol for stress response 
  • Maybe sensitive to sedatives
  • Large tongue may lead to difficult airway
  • Goiter may compress airway

17

What is a myxedema coma? s/s?

  • Extreme hypothyroidism
  • Medical emergency
    • 25 -50% mortality
  • Coma
  • Hypoventilation
  • Hyponatremia (SIADH)
  • CHF- incrase fluid retention can cause CHF
  • Bradycardia
  • Maybe precipitated by surgery, trauma, or infection

18

Treatment myxedma coma?

  • Tracheal intubation and controlled ventilation
  • Levothyroxine 200 -300 mg IV- monitor HR, if CAD, don't want to increase their HR too high
  • Hydrocortisone 100 mg
  • Keep warm
  • Replace electrolytes as needed

19

What is the parathyroid? Functions?

  • 4 small endocrine glands located on the back of the thyroid gland
    • Chief cells
  • Produces parathyroid hormone
    • Principal regulator of calcium and phosphate homeostasis

Functions:

  • Increases osteoblast activity – increase calcium and phosphorous levels in circulation
  • Increases renal tubular reabsorption of calcium
  • Stimulates the synthesis of 1,25-dihydroxycholecalciferol (active Vit D)- causes intestine to absorb more Ca
  • Increased phosphate excretion- if phophate lowered then Ca can increase because Ca binds to phosphate

20

Role of calcium in body?

Regulating heart rate, muscle contraction, nerve impulse, strong bones & teeth, blood clotting, & regulating heart rate 

  • Total body calcium
    • 99% in skeleton
    • 1% in blood
      • 45% bound to proteins like albumin and globulins- as albumin go down, calcium goes down. need to use albumin corrected Ca level
      • 55% unbound ionized
        • 45% ionized –ACTIVE form
        • 10% complexed with bicarbonate, phosphate, or citrate

21

What is the homeostasis of blood calcium level?

  • Elevated calcium levels detected
  • thyroid releases calcitonin
  • calcitonin allows blood calcium levels to fall
  • if calcium falls too low, parathyroid detects
  • parathyroid releases PTH
  • PTH allows blood calcium levels to rise

22

Primary and secondary causes of hyperparathyroidism?

  • Primary
    • Parathyroid adenoma or hyperplasia
    • Multiple endocrine neoplasm
  • Secondary
    • Vitamin D deficiency
    • Kidney disease (decreased Vit D conversion)
    • Intestinal malabsorption syndrome

23

S/S Hyperparathyroidism?

  • Neuro
    • Mental status changes – delirium, psychosis, or coma
  • CV
    • Hypertension, ECG changes (prolonged PR, short QT & wide T waves), & arrhythmias
  • GI
    • N/V, constipation, & pancreatitis
  • Renal
    • Stones (r/t excess calcium), polyuria, polydipsia, impaired renal concentrating ability, & dehydration
  • Musculoskeletal
    • Muscle weakness and osteoporosis

24

Diagnosis hyperparathyroidism?

  • Total calcium: > 10.4 mg/dl
  • Ionized calcium: > 1.5 mmol./L; >6 mg/dL
  • Elevated PTH
  • Increased 1,25 Vit D
  • Decreased Phosphate

25

Hyperparathyroidism treatment?

  • Mild (10.4 – 11.5 mg/dl)
    • IV normal saline (dilution) & loop diuretics (reduce reabsorption)
  • Moderate (> 11.5 mg/dl)
    • Continue normal saline & loop diuretics
    • Bisphosphonates (inhibit osteoclasts)
    • Calcitonin ( inhibits osteoclasts)
    • Chloroquine (inhibits Vit D conversion)
    • Mithramycin (Inhibits osteoclasts)
      • Toxic side effects – thrombocytopenia, hepatic & renal toxicity, azotemia 
  • Severe
    • Dialysis

26

Anesthesia management for hyperparathyroidism?

  • Low threshold to get EKG
  • No evidence that a specific anesthetic drug or technique has advantages over another
  • Scheduled
    • No special monitors usually required
  • Emergency
    • A-line (frequent lab draws), central line, & Foley
  • Unpredictable response to neuromuscular blockade
    • May require decreased dosing & frequent monitoring
  • Careful positioning- osteoporosis

27

Primary and secondary causes hypoparathyroidism?

  • Primary
    • Parathyroid surgery (removal for hyperparathyroidism)
    • Accidental removal during thyroid surgery
  • Secondary
    • Suppression (severe hypomagnesemia, burns, or sepsis)
    • Vitamin D deficiency
    • Renal failure (hyperphosphatemia)
    • Idiopathic hypoparathyroidism (congenital)
    • Acquired hypoparathyroidism (autoimmune disease)
    • Genetic (DiGeorge Syndrome)
    • Heavy metal damage (copper)

28

S/S hypoparathyroidism?

  • Neuro
    • Anxiety, depression, or psychosis
  • CV
    • Hypotension, ECG changes (prolonged QT interval), CHF
  • Resp
    • Apnea or laryngeal spasms
  • Neuromuscular
    • Tetany
      • Chvostek’s
      • Trousseau’s
    • Paresthesia

29

Diagnosis hypoparathyroidism?

  • Total calcium: < 8.5 mg/dl
  • Ionized calcium : < 4.0
  • Increased phosphate
  • Decreased PTH
  • Decreased 1,25 Vitamin D

30

What is trousseau's sign?

  • Induction of carpopedal spasm by inflation of sphygomomanometer above SBP for 3 min
  • Response- carpopedal spasm characterized by:
    • adduction of thumb
    • flexion of metacarpopharlangeal joints
    • extension of the interphalangeal joints
    • flexion of wrist