Endocrine - Pituitary

Question 1

Endocrine Glands

Answer 1

Secrete hormones DIRECTLY into surrounding extracellular fluid

Question 2

Exocrine Glands

Answer 2

Products are discharged via ducts

Question 3

What mediates the endocrine system?

Answer 3

HORMONES

Question 4

What are hormones?

Answer 4

Chemical messengers that transport information from initial cells to target cells

Question 5

Hormone Secretion Regulation

Answer 5

• Neural control
• Biorhythms
• Feedback mechanisms

Question 6

Hormone Neural Control

Answer 6

Suppress or stimulate hormone secretion
Stimuli include pain, smell, touch, stress, sight, taste
Catecholamines, ADH, & cortisol are hormones under neural control

Question 7

Hormone Biorhythms

Answer 7

Genetically encoded or acquired biorhythms
Intrinsic hormonal oscillations - circadian, weekly, or seasonal
Potential to vary w/ life stages

Question 8

Hormone Feedback Mechanisms

Answer 8

Negative or positive

Question 9

Anterior Pituitary

Answer 9

Adenohypophysis
80% pituitary
Secretes 6 hormones 
- Growth hormone
- Adrenocorticotropic ACTH
- Thyroid-stimulating TSH
- Follicle-stimulating FSH
- Luteinizing hormone
- Prolactin

Question 10

TSH

Answer 10

Thyrotropin-releasing hormone TRH → TSH

Target site = thyroid glands

Question 11

ACTH

Answer 11

Corticotropin-releasing hormone CRH → ACTH
Target site = adrenal cortex zona fasiculata & reticularis
CORTISOL

Question 12

FSH/LH

Answer 12

Gonadotropin-releasing hormone → FSH/LH
Target site = gonads (testes/ovaries)
Estrogen, progesterone, testosterone

Question 13

Prolactin

Answer 13

Anterior pituitary hormone
Prolactin releasing & inhibitory hormone/factor
Lactotroph
Target site = breasts

Question 14

Growth Hormone

Answer 14

Anterior pituitary hormone
Growth hormone releasing & inhibitory hormone/factor
Somatotroph
Target site = all tissues

Question 15

Primary Pituitary Disorder

Answer 15

Defect to the peripheral endocrine gland (target organ)

Question 16

Secondary Pituitary Disorder

Answer 16

Pituitary defect
(ex: tumor)

Question 17

Tertiary Pituitary Disorder

Answer 17

Hypothalamus defect (not common)

Question 18

Panhypopituitarism

Answer 18

Generalized pituitary hypofunction

Question 19

Panhypopituitarism Causes

Answer 19

Non-functioning tumors compress & destroy normal pituitary tissue
Hypophysectomy
Postpartum shock
Irradiation
Trauma
Infiltrative disorders

Question 20

Anterior Pituitary Hyposecretion

Treatment

Answer 20

Surgical tumor removal

Hormone replacement therapy - thyroid hormone, glucocorticoids, vasopressin

Question 21

Anterior Pituitary Hypersecretion

Answer 21

Usually caused by benign adenomas
Prolactin → amenorrhea, infertility, ↓libido, impotence
ACTH → Cushing’s disease
Growth hormone → promotes growth all tissues capable to grow
Tumors that secrete thyrotropin or gonadotropin are rare

Question 22

Growth Hormone Normal Secretion

Answer 22

Secretion increases during stress, hypoglycemia, exercise, & deep sleep
Stimulate insulin-like growth factor type 1 (IGF-1) production that mediates GH effects
Skeletal muscle, heart, skin, & visceral organ undergo hypertrophy & hyperplasia d/t GH & IGF-1

Question 23

Growth Hormone Hypersecretion

Answer 23

Usually caused by GH secreting pituitary adenoma

Question 24

Gigantism

Answer 24

GH hypersecretion prior to puberty or before growth plates closure
8-9’ tall

Question 25

Acromegaly

Answer 25

GH hypersecretion in adults after growth plates closed (adolescence) Sustained GH hypersecretion → tissue growth

Question 26

Acromegaly S/S

Answer 26

``` Skeletal & soft tissue overgrowth Large mandible & tongue → potential difficult intubation Tissue hypertrophy around vocal cords Visceromegaly Osteoarthritis Glucose intolerance Skeletal muscle weakness Extrasellar tumor excision ```

Question 27

Acromegaly Comorbidities

Answer 27

HTN, cardiomyopathy, & ischemic heart disease Diabetes Osteoarthritis & skeletal muscle weakness/fatigue ↑lung volumes & sleep apnea Organ enlargement - liver, spleen, kidneys, heart

Question 28

Acromegaly Treatment

Answer 28

Restore normal GH levels Preferred initial treatment - microsurgical tumor removal w/ gland preservation Small tumors transsphenoid approach Large tumors intracranial approach Irradiation and/or suppressant drug therapy as adjunct to shrink tumor for non-surgical candidates

Question 29

Acromegaly Anesthetic Considerations

Answer 29

Difficult mask/airway Sleep apnea Postop respiratory obstruction or failure Systemic HTN, ischemic heart disease, arrhythmias Monitor blood glucose Stress-level glucocorticoid therapy & thyroid replacement

Question 30

Pituitary Surgery | Preop Evaluation

Answer 30

Check electrolytes, hormone levels, & glucose Imaging to assess tumor extent EKG to assess LV hypertrophy or arrhythmias Consider echo w/ cardiac dysfunction patients Optimize cardiac function prior to surgery Check collateral wrist circulation prior to A-line insertion (potential ulnar flow impede d/t carpal tunnel ligament hypertrophy)

Question 31

Transsphenoid Approach

Answer 31

``` Elevate HOB 15° A-line Lumbar drain VAE risk Submucosal epi injections to vasoconstrict → HTN Intraop hypotension d/t inadequate cortisol secretion Muscle relaxation & smooth extubation Neurological exam postop ```

Question 32

Transsphenoid Approach Complications

Answer 32

``` Cranial nerve damage Epistaxis Hyponatremia CSF leak Diabetes insipidus ```

Question 33

Posterior Pituitary

Answer 33

Neurohypophysis 20% pituitary Secretes ADH (vasopressin) & oxytocin (Pitocin)

Question 34

ADH

Answer 34

Antidiuretic hormone or vasopressin Controls renal water reabsorption Regulates serum osmolarity

Question 35

Oxytocin

Answer 35

Stimulates uterine contractions Breast myoepithelia cells - milk ejection during lactation Induces labor & decreases postpartum bleeding

Question 36

Vasopressin Receptors

Answer 36

V1 - mediates vasopressin (refractory hypotension) V2 - mediates water reabsorption in renal collecting ducts (DDAVP target site) V3 - located in CNS & stimulates corticotrophin secretion modulation

Question 37

Stimuli to release ADH:

Answer 37

``` ↑plasma Na+ ↑serum osmolality ↓blood volume Smoking (nicotine) Pain or stress Nausea Vasovagal reaction ANG II PPV ```

Question 38

Diabetes Insipidus

Answer 38

Cause: surgical trauma to posterior pituitary Reversible Insufficient ADH ↑UOP ↓urine osmolarity & specific gravity ↑serum electrolytes Hypernatremia

Question 39

DI Types

Answer 39

Neurogenic or central caused by inadequate ADH release | Nephrogenic - renal tubular resistance to ADH

Question 40

Neurogenic DI Causes

Answer 40

Head trauma Brain tumors Neurosurgery Infiltrating pituitary lesions

Question 41

Nephrogenic DI

Answer 41

Associated w/ - Hypo/hyperkalemia - Genetic mutations - Hypercalcemia - Medication induced nephrotoxicity

Question 42

ADH Deficiency S/S

Answer 42

Polyuria >2mL/kg/hr Dilute unconcentrated urine Dehydration Hypernatremia Na+ >145mEq/L ↑serum plasma osmolarity >290mOsm/L ↓urine osmolarity <300mOsm/L & specific gravity <1.01 Neurological hyperreflexia, weakness, lethargy, seizures, & coma

Question 43

Significant/Complete DI

Answer 43

Plasma osmolarity >290mOsm/L

Question 44

DI Treatment

Answer 44

``` Monitor UOP & electrolytes DDAVP or vasopressin Restrict Na+ intact Adequate fluid replacement UO 1:1 ```

Question 45

DDAVP

Answer 45

``` Desmopressin ↑factor VIII Selective V2 agonist Admin 30-90min before surgery DOA 8-12 hours Less V1 (vasopressor) activity Enhanced antidiuretic properties Nasal 5-40mcg/day SQ 0.5-2mcg/day BID ```

Question 46

Posterior Pituitary Preop Assess

Answer 46

Assess plasma electrolytes, renal function, & plasma osmolarity Dehydration → sensitive to general anesthesia hypotensive effects Replace intravascular volume w/ isotonic fluids over 24-48hrs

Question 47

ADH Deficiency Preop Treatment

Answer 47

Surgery stress increases ADH secretion Complete DI pre-treat w/ DDAVP 1-2mcg IV Q12H Vasopressin 5-10 units IM/SQ Q8-12H Caution w/ CAD patients → HTN d/t arterial vasoconstriction Measure UOP, plasma osmolarity, & serum Na+ Admin isotonic fluids

Question 48

SIADH

Answer 48

Syndrome inappropriate antidiuretic hormone ↑ADH ↑renal H2O reabsorption despite hyponatremia & plasma hypotonicity Intracellular & extracellular fluid expansion Hemodilution & weight gain UOP hypertonic/concentrated related to plasma

Question 49

SIADH Causes

Answer 49

``` Hypothyroidism Pulmonary infection Small cell lung carcinoma Head trauma Intracranial tumors Pituitary surgery Medications ```

Question 50

SIADH S/S

Answer 50

``` Water intoxication ↓serum osmolarity <270mOsm/L Dilutional hyponatremia <130mOsm/L ↓UOP Hypertonic/concentrated urine Neurological cerebral edema → lethargy, headache, nausea, confusion, seizures, & coma ```

Question 51

SIADH Treatment

Answer 51

Mild - fluid restriction 800-1,000mL/day NS Consider hypertonic saline (symptomatic patients or serum Na+ <115-120mEq/L) w/ or w/o loop diuretic Monitor serum Na+ Q2H

Question 52

Sodium Replacement

Answer 52

SLOWLY 1-2mEq/L/hr or 6-12mEq/L/day Prevent acute loss brain H2O Central pontine demyelination syndrome → permanent neurological damage

Question 53

SIADH Anesthetic Considerations

Answer 53

Isotonic solution w/ fluid restriction CVP to help monitor fluid status & guide replacement therapy Closely monitor UOP, urine osmolarity, plasma osmolarity, & serum Na+ concentration Prevent nausea → triggers ADH release