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Cap.12 Endocrino Flashcards

1
Q

What embryologic structures does the thyroid originate from?

A

The medial thyroid comes from the first and second pharyngeal pouches
Lateral portions of the thyroid and parafollicular C cells arise from the fourth and fifth pharyngeal pouches

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2
Q

What is the arterial supply of the thyroid?

A

Superior thyroid artery (from external carotid artery) Inferior thyroid artery (from thyrocervical trunk)

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3
Q

What is the venous drainage of the thyroid?

A

Superior and middle thyroid veins (drain into internal jugular vein) Inferior thyroid veins (drain into innominate and brachiocephalic veins)

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4
Q

The recurrent laryngeal nerve innervates all of the muscles of the larynx except this muscle?

A

Cricothyroid muscle, which is innervated by the external branch of the superior laryngeal nerve

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5
Q

What structures do the recurrent laryngeal nerves wrap around?

A

Subclavian artery on the right

Arch of the aorta on the left

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6
Q

Injury to which nerve results in loss of projection and voice fatigability?

A

Superior laryngeal nerve

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7
Q

What is the mechanism of action of propylthiouracil (PTU) and methimazole?

A

Both drugs block peroxidase oxidation of iodide to iodine, thereby inhibiting incorporation of iodine into T4 and T3
PTU also inhibits peripheral conversion of T4 to T3

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8
Q

Which drug crosses the placenta: PTU or methimazole?

A

Methimazole

PTU is the safer choice in pregnancy

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9
Q

When steroids are given in severe or acute hyperthyroid conditions? How do they work?

A

Steroids inhibit peripheral conversion of T4 to T3 and lower serum TSH by suppressing the pituitary-thyroid axis

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10
Q

What is the Wolff-Chaikoff effect?

A

Large doses of iodine given after an antithyroid medication can inhibit thyroid hormone release by disrupting the coupling of iodide
This is a transient effect

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11
Q

What is the most common cause of hyperthyroidism?

A

Graves disease, also known as diffuse toxic goiter, is the cause of 60% to 80% of hyperthyroidism

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12
Q

What is the etiology of Graves disease?

A

Autoantibodies to TSH receptors (also called thyroid-stimulating antibodies or TSAb)
bind and stimulate thyroid hormone production
This leads to thyrotoxicosis, diffuse goiter, pretibial myxedema, ophthalmopathy

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13
Q

What is the treatment for Graves disease?

A
  • Antithyroid medication
  • Thyroid ablation
  • With/without thyroidectomy
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14
Q

A 55-year-old woman presents with a 3-year history of fatigue and mild, diffuse, nontender thyroid enlargement and 15-lb weight loss. What is the most likely diagnosis?

A

Hashimoto thyroiditis

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15
Q

What is the most common cause of hypothyroidism in adults?

A

Hashimoto thyroiditis

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16
Q

What is the first-line treatment for Hashimoto thyroiditis?

A

Thyroid hormone replacement

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17
Q

What will pathology show in a patient with Hashimoto thyroiditis?

A

Lymphocytic infiltrate

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18
Q

A 35-year-old female presents with sudden onset of severe pain and associated swelling and tenderness of her thyroid with fever, chills, and dysphagia following an acute upper respiratory infection. What is the most likely diagnosis?

A

Acute suppurative thyroiditis

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19
Q

What is the treatment for acute suppurative thyroiditis?

A

Antibiotics

Occasionally, abscess drainage

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20
Q

A 35-year-old female presents with moderate swelling and tenderness of her thyroid with repeated exacerbations and remissions over several months following an acute upper respiratory infection. What is the most likely diagnosis?

A

Subacute (de Quervain) thyroiditis

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21
Q

What is the treatment for subacute (de Quervain) thyroiditis?

A

NSAIDs, steroids

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22
Q

A 40-year-old female presents with hypothyroidism and symptoms of tracheal and esophageal compression and is found to have dense fibrosis throughout her thyroid gland. What is the most likely diagnosis?

A

Riedel fibrous struma
Painless, progressive goiter
Usually euthyroid may become hypothyroid

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23
Q

What is the treatment for Riedel fibrous struma?

A

Thyroid hormone replacement and steroids

Surgery may be necessary to relieve obstructive symptoms

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24
Q

What is the treatment of thyroid storm?

A
  • PTU or methimazole q4 to 6 hours and inorganic iodide to block synthesis and release of thyroid hormones
  • Dexamethasone to inhibit peripheral conversion of T4 to T3
  • Propanolol
  • Fever reduction
  • General resuscitation
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25
Q

What is the most common cause of thyroid enlargement?

A

Multinodular goiter

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26
Q

What are indications for surgery with a multinodular goiter?

A
  • Inability to rule out cancer
  • Compressive symptoms
  • Cosmetic deformity
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27
Q

What is the diagnostic test of choice for the evaluation of a thyroid nodule?

A

FNA
It has a sensitivity of 86% and specificity of 91%
Initial cytology is nondiagnostic in 20% to 25% of cases
However, a diagnosis of malignancy in FNA is highly accurate, approaching 100%

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28
Q

What is usually the first manifestation of multiple endocrine neoplasia (MEN) 2a and 2b?

A

Medullary thyroid carcinoma (MTC)

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29
Q

What are the cytologic features of MTC?

A

Amyloid among neoplastic cells
Immunohistochemistry positive for calcitonin
Positive staining for carcinoembryonic antigen (CEA) or calcitonin gene-related peptide Heterogeneity with polygonal or spindle-shaped cells

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30
Q

What percentage of MTC is sporadic?

A

75% to 80%
Unable to differentiate familial versus sporadic at presentation—all should be tested for rearranged during transfection (RET) mutation, pheochromocytoma, and
hyperparathyroidism

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31
Q

What operation should be done for MTC?

A

Total thyroidectomy

High incidence of multicentric disease

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32
Q

By what age should MEN 2a and MEN 2b patients undergo total thyroidectomy?

A

MEN 2a—age 6

MEN 2b—age 1 to 2

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33
Q

How can you follow patients after thyroidectomy for MTC?

A

Calcitonin levels

History and physical examination

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34
Q

What are the cytologic features indicative of anaplastic thyroid carcinoma?

A

Grossly firm and white

Marked heterogeneity with spindle, polygonal, or multinucleated cells

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35
Q

What is the prognosis for anaplastic thyroid carcinoma?

A

Poor—only few survive more than 6 months

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36
Q

Who typically gets anaplastic thyroid carcinoma?

A

Elderly patients with a long-standing goiter

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37
Q

What is the treatment for a small anaplastic thyroid carcinoma?

A

Total thyroidectomy with or without external beam radiation

Has small improvement in survival, especially for younger patients

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38
Q

What is the treatment for anaplastic thyroid carcinoma with compressive symptoms?

A

Debulking surgery with tracheostomy

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39
Q

Which patient has a higher likelihood of malignancy: the patient with a solid thyroid lesion versus cystic thyroid lesion?

A

Solid thyroid lesion

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40
Q

Which patient has a higher likelihood of malignancy: the patient with a solitary thyroid lesion versus multiple thyroid lesions?

A

Solitary thyroid lesion

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41
Q

Which patient has a higher likelihood of malignancy: the patient with a hot thyroid lesion versus cold thyroid lesion?

A

Cold thyroid lesion

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42
Q

Which type is the most common thyroid cancer and has the best prognosis?

A

Papillary thyroid cancer, about 70% to 80% of all thyroid cancers

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43
Q

Which subtypes carry a worse prognosis?

A
  • Insular
  • Columnar
  • Tall cell
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44
Q

What are the histologic findings for papillary thyroid carcinoma?

A

Psammoma bodies

Orphan Annie nuclei

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45
Q

What is the treatment for papillary thyroid carcinoma?

A

High-risk, large (>2 cm), or bilateral tumors—total thyroidectomy
Low-risk, small (<1 cm), or unilateral tumors—thyroid lobectomy and isthmusectomy

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46
Q

What laboratory test is followed after surgery to monitor recurrence?

A

Thyroglobulin

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47
Q

True or False: Positive cervical nodes affect the prognosis of papillary thyroid carcinoma?

A

False; positive cervical nodes do not affect the prognosis of papillary thyroid carcinoma as long as
disease is resectable.

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48
Q

What are the histologic findings needed to define malignancy in follicular cancer?

A

Blood vessel, capsular invasion

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49
Q

What is the most common site of distant metastasis for follicular thyroid carcinoma?

A
  • Bone
  • Next most common is lung
  • Spread is hematogenous
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50
Q

Which has a worse prognosis: Hurthle cell carcinoma or Follicular carcinoma?

A

Hurthle cell carcinoma

Higher recurrence rate usually to regional lymph nodes

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51
Q

Name the 3 classifications systems specific to papillary thyroid cancer:

A
  • AGES (age, grade of tumor, extent of tumor, size)
  • AMES (age, metastasis, extent of tumor, size)
  • MACIS (metastasis, age, completeness of resection, local invasion, size)
  • High-risk patients by AGES or AMES criteria: >40 years old, male, capsular invasion or extrathyroidal extension, regional or distant metastases, size >4 cm, or poorly differentiated carcinoma
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52
Q

What is the (tumor, node, metastasis) (TNM) stage for a 57-year-old patient who underwent a total thyroidectomy for a 2.5-cm mass that was determined to be papillary thyroid carcinoma? All lymph nodes were free of disease and there was no extrathyroidal disease.

A

This patient has T2N0M0 disease

Because the patient is older than 45 years, this is stage II papillary thyroid cancer

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53
Q

What are the indications for I-131 therapy?

A
  • All stage III or IV disease
  • All stage II disease younger than 45 years old
  • Most patients 45 years or older with stage II disease
  • Stage I disease who have aggressive histologies, nodal metastases, multifocal disease, and extrathyroid or vascular invasion
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54
Q

What structure are the superior parathyroid glands embryologically derived from?

A

Fourth branchial pouch

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55
Q

What structure are the inferior parathyroid glands embryologically derived from?

A

Third branchial pouch

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56
Q

What structure is the thymus embryologically derived from?

A

Third branchial pouch

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57
Q

What is the arterial blood supply to the superior parathyroid glands?

A

Inferior thyroid artery (occasionally by branches of the superior thyroid artery)

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58
Q

What is the arterial blood supply to the inferior parathyroid glands?

A

Inferior thyroid artery

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59
Q

What is the spatial relationship of the inferior parathyroid gland to the recurrent laryngeal nerve and inferior thyroid artery?

A

Inferior parathyroid glands are medial to the recurrent laryngeal nerves and located below the inferior thyroid artery

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60
Q

What is the spatial relationship of the superior parathyroid gland to the recurrent laryngeal nerve and inferior thyroid artery?

A

Superior parathyroid glands are lateral to the recurrent laryngeal nerves and located above the inferior thyroid artery

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61
Q

Describe the mechanisms by which PTH increases serum calcium concentration:

A

Bone—enhances resorption of bone matrix by osteoclasts
Kidney—increases tubular reabsorption of filtered calcium and decreases tubular reabsorption of filtered phosphate
Intestine—stimulates renal vitamin D complex synthesis, which increases intestinal absorption of calcium (indirect effect)

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62
Q

What laboratory test is the most sensitive and specific way to diagnose hyperparathyroidism?

A

Intact parathyroid hormone level (elevated in >95% of patients with primary hyperparathyroidism)

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63
Q

What is the half-life of parathyroid hormone?

A

2 to 4 minutes

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64
Q

What is the desired decline in the intraoperative parathyroid hormone assay that confirms that the suspected abnormal parathyroid tissue was resected?

A

50% decrease from baseline PTH or a drop of the PTH to the normal range

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65
Q

Describe the process of vitamin D formation and activation:

A

7-dehydrocholesterol undergoes ultraviolet activation to form vitamin D3 (cholecalciferol) → hydroxylated in the liver to form 25-hydroxycholecalciferol → undergoes a second hydroxylation in the kidneys to its most active form 1,25-dihydroxycholecalciferol

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66
Q

What cells secrete the hormone calcitonin?

A

Parafollicular (C cells) of the thyroid

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67
Q

Which type(s) of hyperparathyroidism (primary, secondary, or tertiary) is associated with high serum PTH levels and high-normal to elevated serum calcium levels?

A

Primary and tertiary hyperparathyroidism

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68
Q

Which type of hyperparathyroidism is associated with high serum PTH levels and low-normal to low serum calcium levels?

A

Secondary hyperparathyroidism

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69
Q

Which type of hyperparathyroidism is considered a compensatory response of the parathyroid glands to hypocalcemia?

A

Secondary hyperparathyroidism

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70
Q

Which type of hyperparathyroidism occurs when long-standing stimulation of the parathyroid glands by hypocalcemia results in autonomous hyperfunctioning of the parathyroid glands?

A

Tertiary hyperparathyroidism

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71
Q

What acid-base disturbance can be seen with primary hyperparathyroidism?

A

Hyperchloremic metabolic acidosis

72
Q

What chloride:phosphate ratio is highly suggestive of primary hyperparathyroidism?

A

Chloride:phosphate ratio >33 is highly suggestive of primary hyperparathyroidism

73
Q

What is the most common cause of primary hyperparathyroidism? Second most common? Third most common?

A
  • Single adenoma (80%)
  • Diffuse hyperplasia (15%)
  • Multiple adenomas (4%)
74
Q

What oncogene increases the risk for a parathyroid adenoma?

A

PRAD-1

75
Q

What are the classic gross findings diagnostic of a parathyroid adenoma?

A

Single enlarged gland with 3 normal or small remaining glands associated with the histologic finding of hyperplastic tissue

76
Q

Indications for initial parathyroidectomy for a patient with primary hyperparathyroidism: Symptomatic:

A

Typical bone, renal, gastrointestinal, neuromuscular symptoms

77
Q

Indications for initial parathyroidectomy for a patient with primary hyperparathyroidism: Asymptomatic:

A

-History of an episode of life-threatening hypercalcemia –Presence of kidney stones detected by abdominal imaging Medical surveillance not desirable/possible
Serum calcium level >1 mg/dL above upper limit of normal Age <50 years
Osteoporosis (bone density T-score 30%
Elevated 24-hour urinary calcium excretion (>400 mg/d)

78
Q

Indications for initial parathyroidectomy for a patient with primary hyperparathyroidism: Asymptomatic:

A
  • History of an episode of life-threatening hypercalcemia
  • Presence of kidney stones detected by abdominal imaging
  • Medical surveillance not desirable/possible
  • Serum calcium level >1 mg/dL above upper limit of normal -Age <50 years
  • Osteoporosis (bone density T-score 30%
  • Elevated 24-hour urinary calcium excretion (>400 mg/d)
79
Q

What is the difference between persistent and recurrent hyperparathyroidism?

A

Persistent refers to hypercalcemia that remains within 6 months of initial surgery Recurrent refers to hypercalcemia that returns after 6 months of initial surgery

80
Q

What is the most common cause of persistent hyperparathyroidism?

A

Missed adenoma

81
Q

What are the causes for recurrent hyperparathyroidism?

A

New adenoma formation or recurrent parathyroid cancer

82
Q

Indications for reoperative parathyroidectomy for persistent or recurrent disease:

A
  • Ongoing nephrolithiasis
  • Worsening renal function
  • Worsening bone disease as evidenced by bone mineral density scores Associated neuromuscular symptoms
  • Associated psychiatric symptoms
  • Worrisome progressive hypercalcemia
83
Q

Indications for parathyroidectomy in patients with secondary hyperparathyroidism:

A
  • Development of open ulcerative skin lesions from calcinosis or calciphylaxis
  • Persistent bone pain or pathologic fractures (renal osteodystrophy)
  • Ectopic calcifications
  • Intractable pruritus
  • Worsening disease with failure of medical management
84
Q

General intraoperative algorithm for searching a “missing” parathyroid gland:

A

Open and inspect the thyroid capsule, palpate gland Consider intraoperative US
Dissect superior thymic/paratracheal tissue and complete a cervical thymectomy for missing inferior parathyroid glands
Mobilize the pharynx and esophagus to look in the parapharyngeal/retropharyngeal/esophageal spaces for missing superior glands
Open the carotid sheath and expose the common carotid and inspect for potential parathyroid glands
Ligate the ipsilateral inferior thyroid artery and/or perform a thyroid lobectomy (record the location of all confirmed glands identified)
End the procedure and follow patient for any evidence of persistent hypercalcemia
Can reimage patient for evidence of ectopic parathyroid adenoma

85
Q

What is the most common location for a “missing” parathyroid gland at reoperation?

A

Normal anatomic position

86
Q

Generally what is the recommended period of time that cryopreserved parathyroid tissue should not be transplanted?

A

24 months after freezing

87
Q

How is parathyroid tissue autotransplanted?

A

The resected parathyroid tissue is minced into 1-mm fragments. A pocket is then made in the desired muscle. Ten to 20 1-mm fragments of minced parathyroid tissue are inserted into the muscle pocket, which is closed and tagged with hemoclips/suture (for future identification)

88
Q

Why is the forearm used preferentially over the sternocleidomastoid for autotransplantation of parathyroid tissue?

A

Easier to re-explore if patient develops persistent or recurrent disease from autotransplanted tissue
Easier to identify PTH gradients with peripheral blood draws in forearm versus neck (can place BP cuff)

89
Q

Why do some patients experience postoperative hypocalcemia?

A

Bone hunger, hypomagnesemia, failure of parathyroid remnant or graft

90
Q

What imaging study is used for preoperative localization for reoperative parathyroid surgery and for minimally invasive parathyroidectomy?

A

Technetium-sestamibi scan

91
Q

In general, what is the most common cause of hypoparathyroidism?

A

Surgical trauma to parathyroid glands during thyroid or parathyroid exploration

92
Q

What operation is performed for parathyroid carcinoma?

A

En bloc tumor resection that includes ipsilateral thyroid lobectomy, and resection of adjacent soft tissues

93
Q

True or False: A frozen section biopsy for suspected parathyroid cancer should be performed before surgical excision?

A

False; capsular rupture may occur with the potential of spreading tumor cells in the neck.

94
Q

What is the most common location for parathyroid cancer to metastasis?

A

Lung

95
Q

What is the most common cause of hyperparathyroidism in MEN 1?

A

Parathyroid hyperplasia (90%)

96
Q

Which of the following needs to be corrected first in MEN 1—hyperparathyroidism, gastrinoma, or prolactinoma?

A

Hyperparathyroidism; need to correct calcium first

97
Q

Which of the following needs to be corrected first in MEN 2—hyperparathyroidism, pheochromocytoma, or MTC?

A

Pheochromocytoma

98
Q

What hormones are released from the posterior pituitary?

A

ADH and oxytocin

99
Q

What hormones are released from the anterior pituitary?

A

ACTH, FSH, LH, GH, TSH, and prolactin

100
Q

What gonadotropic hormone promotes spermatogenesis or ovarian follicle maturation?

A

FSH

101
Q

What gonadotropic hormone promotes testicular testosterone production?

A

LH

102
Q

What drug may be given as primary therapy in patients who are not operative candidates with excessive production of GH by a pituitary adenoma?

A

Octreotide (decreases serum levels of GH and the downstream growth factor somatomedin C)

103
Q

What is the size cutoff to determine whether a pituitary lesion is a microadenoma versus macroadenoma?

A

Microadenoma <1 cm

Macroadenoma >1 cm

104
Q

What imaging study is the gold standard for evaluating the pituitary?

A

MRI with gadolinium

105
Q

What is the most common pituitary adenoma?

A

Prolactinoma

106
Q

What is the treatment for prolactinoma?

A

Bromocriptine

Transsphenoidal resection for failure of medical management

107
Q

Meningococcal sepsis/infection results in adrenal gland hemorrhage leading to adrenal insufficiency:

A

Waterhouse-Friderichsen syndrome

108
Q

Results from arachnoid herniation secondary to a congenital defect in the diaphragma sellae:

A

Empty sella syndrome (primary)

109
Q

A 35-year-old female with 1-week postpartum history of placental hemorrhage who presents with trouble lactating and amenorrhea:

A

Sheehan syndrome

110
Q

Hyperpigmentation and pituitary enlargement (resulting in amenorrhea and visual problems) after bilateral adrenalectomy:

A

Nelson syndrome

111
Q

Calcified cyst that is remnant of Rathke pouch and can present with endocrine abnormalities, headache, hydrocephalus, and visual disturbances:

A

Craniopharyngioma

112
Q

What are signs/symptoms of Cushing syndrome?

A

Acne, buffalo hump, depression, diabetes, easy bruising, hirsutism, hypertension, moon facies, myopathy, purple striae, truncal obesity, weakness

113
Q

What enzyme is present almost exclusively in the adrenal medulla and organ of Zuckerkandl? What does it do?

A

Phenylethanolamine-N-methyltransferase (PNMT) Converts norepinephrine to epinephrine via methylation

114
Q

What enzyme is involved in the rate-limiting step of catecholamine synthesis?

A

Tyrosine hydroxylase (hydroxylates tyrosine to dihydroxyphenylalanine [DOPA])

115
Q

What are the intermediate substrates involved in the synthesis of epinephrine from tyrosine?

A

Tyrosine→DOPA→Dopamine→Norepinephrine→Epinephrine

116
Q

Which artery does the superior adrenal artery originate from?

A

Inferior phrenic artery

117
Q

Which artery does the middle adrenal artery originate from?

A

Aorta

118
Q

Which artery does the inferior adrenal artery originate from?

A

Renal artery

119
Q

The left adrenal vein empties into which vein?

A

Left renal vein

120
Q

The right adrenal vein empties into which vein?

A

Inferior vena cava

121
Q

What does the zona glomerulosa of the adrenal cortex produce?

A

Aldosterone

122
Q

What does the zona fasciculata of the adrenal cortex produce?

A

Glucocorticoids

123
Q

What does the zona reticularis of the adrenal cortex produce?

A

Androgens/estrogens

124
Q

What is the most common deficiency seen with congenital adrenal hyperplasia?

A

21-hydroxylase deficiency (90%)

125
Q

What are the indications for surgical resection of an adrenal mass?

A

More than 4 to 6 cm, enlarging (0.5 cm over 6 months), functioning, ominous characteristics (nonhomogenous) on imaging

126
Q

What laboratory tests should be ordered in the workup of an adrenal mass?

A

Urine metanephrines/vanillylmandelic acid (VMA)/catecholamines, urine hydroxycorticosteroids, serum potassium
If decreased serum potassium or HTN, then obtain plasma renin and aldosterone

127
Q

Primary hyperaldosteronism accounts for what percentage of all cases of HTN?

A

1%

128
Q

Classic Conn syndrome is characterized by:

A

HTN, hypokalemia, polyuria

129
Q

What test can differentiate primary hyperaldosteronism from secondary hyperaldosteronism?

A

Plasma renin level (suppressed with primary and not suppressed with secondary)

130
Q

What is the #1 cause of primary hyperaldosteronism?

A

Adrenal adenoma

131
Q

What is the aldosterone:renin ratio that is suggestive of an aldosteronoma?

A

20 is diagnostic for primary hyperaldosteronism

132
Q

What is the aldosterone suppression test?

A

Give a saline infusion; if the urinary aldosterone level is elevated (>12 μg/d), the diagnosis of primary hyperaldosteronism is confirmed

133
Q

What is the best imaging modality to distinguish aldosteronoma from bilateral hyperplasia?

A

CT scan of the abdomen with thin cuts (3–5 mm) through the adrenal glands

134
Q

What acid-base disturbance will be seen with primary hyperaldosteronism?

A

Hypochloremic metabolic alkalosis

135
Q

What test can be performed to lateralize an aldosterone producing hyperfunctioning adrenal gland in the setting of adrenal hypertrophy, bilateral nodules, or absence of lesions?

A

Selective venous catheterization for aldosterone sampling

136
Q

What is the adrenal vein aldosterone-to-cortisol ratio required to lateralize an aldosteronoma/unilateral adrenal hyperplasia?

A

At least 5 times higher on the affected side; if ratios from both sides are similar, then suspect bilateral hyperplasia

137
Q

If the captopril test is performed in a patient with an aldosterone-secreting tumor, what will happen to serum aldosterone levels?

A

No change.

If the patient has bilateral adrenal hyperplasia, a captopril test will cause decreased aldosterone levels

138
Q

What competitive inhibitor of aldosterone is usually given to control HTN and normalize potassium levels in a patient with an aldosteronoma/unilateral hyperplasia before surgery?

A

Spironolactone

139
Q

What is the best treatment approach for an aldosteronoma or unilateral hyperplasia?

A

Laparoscopic adrenalectomy

140
Q

What is the treatment for hyperaldosteronism from adrenal hyperplasia?

A

Medical therapy with calcium channel blockers, potassium, and spironolactone. If refractory hypokalemia, then bilateral adrenalectomy, steroids, and fludrocortisone

141
Q

What is the most sensitive and specific test for making the diagnosis of Cushing syndrome?

A

24-hour urinary free cortisol

142
Q

What is the most common site of ectopic ACTH-producing tumor? Second most common site?

A 
#1 Small cell lung carcinoma 
#2 Carcinoid
143
Q

What ACTH level signifies an ACTH-independent cause of endogenous glucocorticoid hypersecretion?

A

<5 pg/mL (low)

144
Q

What ACTH level signifies an ACTH-dependent cause of endogenous glucocorticoid hypersecretion?

A

15 pg/mL (high)

145
Q

How is the low-dose overnight dexamethasone suppression test performed?

A

Administer dexamethasone 1 mg PO at 11 PM; check plasma cortisol at 8 AM the next day. Cortisol level will be markedly suppressed (<1.8 μg/dL) in normal individuals. If cortisol level is not suppressed, the patient has Cushing syndrome.

146
Q

How is the high-dose overnight dexamethasone suppression test performed?

A

Obtain baseline plasma cortisol; administer dexamethasone 8 mg PO at 11 PM; check 8 AM plasma cortisol. Suppression occurs if there is >50% reduction in plasma cortisol, which indicates Cushing syndrome from a pituitary source (if not suppressed, then from an adrenal or ectopic cause).

147
Q

What happens to the ACTH level during a high-dose dexamethasone suppression test with a responsible pituitary tumor?

A

ACTH level is suppressed

148
Q

What happens to the ACTH level during a high-dose dexamethasone suppression test with a responsible ectopic source?

A

ACTH level is not suppressed

149
Q

How is the corticotropin-releasing hormone (CRH) stimulation test performed?

A

Check baseline serum ACTH and cortisol. Give 1 mcg/kg CRH IV. Draw serum ACTH and cortisol 15 minutes after administering CRH.

150
Q

How does the CRH stimulation test distinguish between pituitary versus adrenal tumor versus ectopic ACTH causes of endogenous glucocorticoid hypersecretion?

A

ACTH increases at a minimum of 35% above baseline with pituitary lesions only (others do not)

151
Q

What laboratory tests establish the diagnosis of a virilizing tumor?

A

Increased levels of serum dehydroepiandrostenedione (DHEA-S), serum testosterone, and 24-hour urine 7-hydroxysteroids and 17-ketosteroids

152
Q

How does a dexamethasone suppression test differentiate between an adrenal versus ovarian cause for a virilizing tumor?

A

24-hour ketosteroids and serum androgens will be suppressed with ovarian tumors but not adrenal tumors

153
Q

What happens to gadolinium on MRI for a malignant adrenal tumor? For an adrenal adenoma?

A

Gadolinium persists in a malignant tumor; gadolinium washes out rapidly from an adenoma

154
Q

What is the #1 cause of adrenal insufficiency?

A

Withdrawal of exogenous steroids

155
Q

What electrolyte abnormalities are seen in adrenal insufficiency?

A

Hyponatremia, hyperkalemia

156
Q

What test can be performed to diagnose adrenal insufficiency?

A

ACTH stimulation test

157
Q

What is one of the first signs for the loss of hypothalamic regulation of cortisol secretion?

A

Loss of diurnal variation of cortisol levels

158
Q

What is the safest operation for patients with suspected adrenocortical carcinoma?

A

Open adrenalectomy

159
Q

What medication is commonly used for adjuvant therapy with residual, recurrent, or metastatic adrenocortical carcinoma?

A

Mitotane, a synthetic derivative of the insecticide dichlorodiphenyltrichloroethane (DDT) that directly suppresses the adrenal cortex and modifies the peripheral metabolism of steroids

160
Q

What follow-up is needed for a patient with adrenal tumor <4 cm or 4 to 6 cm treated nonoperatively?

A

Repeat abdominal imaging Q6 months to a year and annual screening for cortisol and catecholamines for 5 years

161
Q

What is the treatment for a patient with adrenal mass >6 cm?

A

Adrenalectomy; most likely malignant

162
Q

What disease process needs to be ruled out before performing a fine-needle aspiration of a solitary adrenal mass?

A

Pheochromocytoma; inadvertent biopsy can be potentially lethal

163
Q

What laboratory test is the most sensitive for the detection of pheochromocytoma?

A

Plasma metanephrines (96%)

164
Q

What is the rule of 10’s for pheochromocytoma?

A

10% bilateral, 10% malignant, 10% extra-adrenal, 10% hereditary, 10% in children

165
Q

What ectopic sites can a pheochromocytoma be found?

A

Organ of Zuckerkandl, thorax/mediastinum, bladder, scrotum

166
Q

What familial syndromes are associated with pheochromocytoma?

A

MEN type 2, Sturge-Weber syndrome, tuberous sclerosis, von Hippel-Lindau disease, neurofibromatosis type I

167
Q

What is usually seen with a hypertensive “spell,” the hallmark clinical presentation of pheochromocytoma?

A

Diaphoresis, headache, palpitations, and paroxysmal HTN

168
Q

True or False: Paragangliomas and pheochromocytomas located in the organ of Zuckerkandl can use PNMT to metabolize norepinephrine to epinephrine?

A

True; paragangliomas and pheochromocytomas in the organ of Zuckerkandl contain PNMT.

169
Q

What medications should be given preoperatively for pheochromocytoma?

A

Phenoxybenzamine 10 mg BID and increase by 20 mg/d until BP and symptoms controlled; add β- blocker 3 days prior to surgery (inderal 10 mg TID); IVF hydration starting 2 days prior to surgery (typically patients are volume contracted)

170
Q

What rapid-acting agents should be available in the operating room when operating on a pheochromocytoma?

A

Neosynephrine, nitroprusside, lidocaine, esmolol, phentolamine

171
Q

What follow-up is recommended after adrenalectomy for pheochromocytoma?

A

Yearly 24-hour urinary metanephrines/catecholamines

172
Q

What is the localizing test of choice for adrenal pheochromocytoma?

A

CT scan of the abdomen with thin cuts (3–5 mm) through the adrenal glands

173
Q

What is the approximate percentage of MEN 2 patients with pheochromocytoma?

A

40%

174
Q

What is the surgical treatment for pheochromocytoma in MEN 2?

A

Bilateral adrenalectomy; trend now is to remove the affected side and observe the contralateral side until there is radiographic/biochemical evidence of disease

175
Q

What is the most common cancer to metastasize to the adrenal gland?

A

Breast cancer

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