Chapter 15 Flashcards
1
Q
Describe pituitary adenomas
A
BENIGN tumors of the anterior pituitary cells that may be functional or nonfunctional (often present with mass effect- i.e. bitemproal heminaopia, hypopituitarism, and HA)
2
Q
How does a prolactinoma present?
A
Presents as galactorrhea and amenorrhea (females) or as decreased libidio and HA (males) (most common type of pitutiary adenoma)
Tx: Dopamine agonists to shrink the tumor before surgery
3
Q
What is a common cause of death in pts with acromegaly due to excessive GH production?
A
cardiac failure
4
Q
What are the things to note about GH adenomas?
A
secondary diabetes mellitus is often present (GH induces liver gluconeogenesis)
Diagnosed by elevated GH and insulin growth-factor 1 (IGF-1) levels along with lack of GH suppression by oral glucose
5
Q
How are GH adenomas tx?
A
Octreotide (somatostatin analog that suppresses GH release),, GH receptor antagonists, or surgery
6
Q
What is hypopituitarism?
A
Insufficient production of hormones by the anterior gland (symptoms arise when 75+% of the parenchyma is lost)
7
Q
What are the most common causes of hypopituitarism?
A
Pituitary adenomas (adults) or craniopharyngiomas (children) due to mass effect or pituitary apoplexy (bleeding into an adenoma)
Sheehan syndrome- pregnancy related infarction of the gland (gland doubles in size during pregnancy, but blood supple does not increase much and blood loss during parturition can precipitate infarction)
Empty Sella Syndrome
8
Q
How does Sheehan syndrome present?
A
poor lactation, loss of pubic hair, and fatigue
9
Q
What is Empty Sella Syndrome?
A
Congenital defect of the sella (herniation of the arachnoid and CSF into the sella compresses the destroys the pituitary gland). Gland is “absent” on imaging
10
Q
What are the products of the posterior pituitary?
A
ADH and oxytocin (made in the hypothalamus and then transported to the posterior pituitary for release)
11
Q
What does oxytocin do?
A
Mediates uterine contraction during labor and release of breast milk (let-down) in lactating women
12
Q
What is central DI?
A
ADH deficiency due to hypothalamic or posterior pituitary pathology (e.g. tumor, trauma, infection, or inflammation)
13
Q
How does central DI present?
A
Polyuria and polydipsia
hypernatremia and high serum osmolarity
Low urine osmolarity and S.G.
14
Q
How is central DI diagnosed?
A
Water deprivation test that fails to increase urine osmolality (tx with desmopressin- ADH analog)
15
Q
What is nephrogenic DI?
A
Imapired renal response to ADH due to inherited mutations or drugs (e.g. lithium and demeclocycline)
Note that desmopressin will NOT be effective for tx in nephrogenic DI
16
Q
What is SIADH?
A
Excessive ADH secretion most often due to ectopic production (e.g. small cell carcinoma of the lung), or CNS trauma, pulmonary infection, and drugs like cyclophosphamide
17
Q
How does SIADH present?
A
Hyponatremia and low serum osmolality
Mental status chanes and seizures (hyponatremia leads to neuronal swelling and cerebral edema)
18
Q
How is SIADH tx?
A
water restriction and demeclocycline
19
Q
What is a thyroglossal duct cyst?
A
cystic dilation of the thryoglossal duct remnant (thyroid develops at the base of the tongue and then travels along the thyroglossal duct to the anterior neck where it normally involute)
20
Q
What is a lingual thyroid?
A
Persistence of thyroid tissue at the base of the tongue presenting as a base of tongue mass
21
Q
Describe hyperthyroidism
A
Increased levels of circulating thyroid hormone increasing the BMR (due to increased synthesis of NaK ATPase) and the sympathetics nervous system activity (due to increased expression of B1-adrenergic receptors)
22
Q
What are the clinical features of hyperthyroidism?
A
Weight loss despite increased appetite
Heat intolerance and sweating
Tachycardia with increased CO
Arrhythmia (e.g. a fib), esp. in the elderly
Tremor, anxiety, insomnia, and heightened emotions
Staring gaze with lid lag
Diarrhea with malabsorption
Oligomenorrhea
Bone resorption with hypercalcemia (risk for osteoporosis)
Decreased muscle mass with weakness
HYPOcholesterolemia
Hyperglycemia due to gluconeogenesis and glycogenolysis
23
Q
What is Grave’s Disease?
A
Autoantibody (IgG) that stimulates TSH receptor (Type II rxn) leading to increased synthesis and release of thyroid hormone (most common cause od hyperthyroidism and classically occurs in women of childbearing age)
24
Q
What are the clinical features of Grave’s Disease?
A
Hyperthyroidism
Diffuse goiter (constant TSH stimulation leads to thyroid hyperplasia and hypertrophy)
Exophthalmos and pretibial myxedema (fibroblasts behind the orbit and overlying the shin express the TSH receptor and TSH activation results in glycoaminoglycen (chondritin sulfate and hyaluronic acid) buildup, inflammation, fibrosis, and edema leading to these symptoms)
25
Describe the histo of Grave's disease
Irregular follicles with **scalloped colloid** and chronic inflammation are seen
26
What are the lab findings of Graves?
27
How is Graves tx?
B-blockers, thioamide, and radioiodine ablation
28
What is a potentially fatal complication of Grave's disease?
Thyroid storm, due to elevated catecholamines and massive hormone excess, usually in response to stress (e.g. surgery, childbirth, etc.)
29
How does a thyroid storm present?
as arrhythmias, _hyperthermia_, and vomiting with **hypovolemic shock**
30
How is a thyroid storm tx?
Propylthiouracil (PTU), BBs, and steroids
PTU inhibits peroxidase-mediated oxidation, organification and coupling steps of thyroid hormone synthesis, as well as peripheral conversion of T4 to T3
31
What causes multinodular goiter?
Enlarged thryoud glands with multiple nodules due to relative iodine defciency (usually nontoxic, aka euthyroid)
32
What is cretinism?
Hypothyroidism in neonates and infants marked by mental retardation, **short stature with skeletal abnormalities, coarse facial features, enlarged tongue, and umbilical hernia**
33
What are the most common causes of cretinism?
maternal hypothyroidism during early pregnancy, thyroid agenesis, dyshormonogenetic goiter, and iodine deficiency
34
What is dyshormonogenetic goiter?
Due to a congenital defect in thyroid hormone production (most commonly involves thryoid peroxidase)
35
What is myxedema?
**Hypo**thyroidism in older children and adults
36
How does myxedema present?
Clinical features based on decreased BMR and decreased sympathetic NS activity and include:
Myxedema (accumulation of GAGs in skin and soft tissue, resulting in deepending of the voice and large tongue)
Weight gain despite normal appetite
Slowing of mental activity
Muscle weakness
Cold intolerance with decreased sweating
HYPERcholesterolemia
Constipation
Oligomenorrhea
Bradycardia, leading to SOB and fatigue
37
What are the most common causes of myxedema?
iodine deficiency and Hashimoto thyroiditis
drugs (e.g. lithium) and surgical removal or radioablation of the thyroid
38
What are the main types of thyroiditis?
Hashimoto
Subacute Granulomatous (De Quervain)
Riedel Fibrosing
39
What is Hashimoto thyroiditis?
**Autoimmune destruction** of the thyroid gland associated with HLA-DR5 (most common cause of hypothyroidism in regions where iodine levels are adequate)
40
How does Hashimoto present?
May initially present as hyperthyroidism (due to follicle damage), but progresses to hypothyroidism (decreased T4 and increased TSH).
41
What ABs are seen in Hashimoto?
Antithyroglobulin and antithyroid peroxidase Abs
42
What are the classic biopsy findings of Hashimoto?
Chronic inflammation with germinal centers and **Hurthle cells** (eosinophilic metaplasia of cells that line follicles)
43
Hashimoto carries an increased risk for what?
**B cell (marginal zone) lymphoma** (presents as an enlarging thyrod gland late in the disease course)
44
What is De Quervain thyroiditis?
Grnaulomatous thyroiditis that follows a viral infection and presents as a TENDER thyroid with trainsient hyperthyroidism (self-limited but may progress to hypothyroidism)
45
What is Riedel Thyroiditis?
Chronic inflammation with extensive fibrosis of the thyroid gland that presents as hypothyroidism with a **hard, immobile nontender** thyroid gland
46
How does thyroid neoplasia present?
Usually as a distinct, SOLITARY nodule (thyroid nodules more likely to be benign than malignant)
Better diagnosed with I131 radioactive uptake studies
47
Hot nodules are seen in what diseases?
Grave's disease or nodular goiter
48
Cold nodules are seen in what diseases?
Adenoma and carcinoma
49
What is a follicular adenoma?
BENIGN proliferation of thyroid follicles surrounded by a fibrous capsule
Usually nonfunctional (less commonly functional)
50
What are the main types of thyroid carcinoma?
Papillary
Follicular
Medullary
Anaplastic
51
What is the most common type of thyroid carcinoma?
Papillary
52
What causes Papillary thyroid carcinoma?
exposure to ionizing radiation in childhood is a major risk factor
53
Describe the histo of Papillary thyroid carcinoma
Comprised of papillae lined by cells with clear "**orphan Annie eye**" nuclei and nuclear grooves
**_Psamomma bodies_**
54
What is the prognosis for papillary thyroid carcinoma?
Often spreads to cervical lymph nodes, but excellent prognsosis (10 yr survival 95+%)
55
Describe Follicular thyroid carcinomas **(spread via heme, not lymph-remember)**
Malignant proliferation of follicles surrounded by a fibrous capsule with invasion through the capsule (invasion helps distinguish between this and follicular adenoma; must exam entire capsule)
Distinction CANNOT be made via FNA
56
Describe medullary thyroid carcinomas
Malignant prolifreation of parafollicular C cells
57
What are C cells?
Neuroendocrine cells that secrete calcitonin (which loweres serum calcium by increasing renal excretion but is inactive at normal physiology levels)
High production with tumor may lead to hypocalcemia
58
Calcitonin produced by medullary thyroid carcinomas often deposit where?
Within the tumor as AMYLOID (biopsy revelas sheets of malignant cells in an amyloid stroma)
59
What are some syndromic forms of medullary thyroid carcinoma?
MEN 2A and 2B
60
What is the triad of MEN 2A?
medullary carcinoma
pheochromocytoma
parathyroid adenomas
61
What is the triad of MEN 2B?
medullary carcinoma
pheochromocytoma
ganglioneuromas of the oral mucosa
62
What is a common presentation of anaplastic carcinoma?
Often involvement of lact structures, leading to dysphagia or respiratory compromise
63
What is the main role of the PTH?
Chief cells regulate serum free (ionized) calcium via PTH secretion which,
Increases bone osteoclast activity, releasing calcium and phosphate
Increases small bowel absorption of calcium and phosphate (indirectly by activating vitD)
Increases renal calcium reabsorption (distal tubule) and decreases phosphate reabsorptions (proximal tubule)
64
What causes primary hyperPTHism?
Excess PTH due to a disorder of the PTH gland itself (most commonly due to parathyroid adenoma (80+%), sporadic parathyroid hyperplasia, and parathyroid carcinoma)
65
What is a parathyroid adenoma?
A BENIGN neoplasm, usually involving a single gland and most commonly resulting in asymptomatic hypercalcemia, but may present with consequences of increased PTH and hypercalcemia such as:
**Nephrolithiasis** (calcium oxalate stones)
**Nephrocalcinosis** (metastatic calcification of renal tubules), potentially leading to renal failure and polyuria
CNS disturbances (e.g. depression and seizures)
Constipation, peptic ulcer, and acute pancreatitis
**Osteitis fibrosa cystica**
66
What is **Osteitis fibrosa cystica**?
Resorption of bone leading to fibrosis and cystic spaces
67
What is this?
Nephrocalcinosis
68
What are the lab findings of primary hyperPTHism?
elevated serum PTH and serum calcium
decreased serum phosphate
increased urinary cAMP
elevated serum alk phosphatase
69
Describe 2ndary hyperparathyoridism?
Excess production of PTH due to a disease process extrinsic to the parathyroid gland (most commonly due to renal failure)
70
How does renal failure cause 2ndary hyperPTHism?
Renal insufficiency leads to decreased phosphate excretion
Elevated serum phosphate binds free calcium
Decreased free calcium stimulates all four PTH glands
Elevated PTH leads to bone resorption (contributing to renal osteodystrophy)
71
What are the lab findings of 2ndary hyperPTHism?
elevated PTH
decreased serum calcium
increased serum phosphate
elevated alk phos
72
What are the major causes of hypoPTHism?
Low PTH due to autoimmune damage to the PTHs, surgical excision, and DiGeorge Syndrome
73
How does hypoPTHism present?
Presents with symptoms related to low serum calcium including
numbness and tingling (particularly circumoral)
Muscle spasms (tetany)- may be elicited with filling of a blood pressure cuff (Torusseau sign) or tapping on the facial nerve (Chvostek sign)
74
What are the lab findings of hypoPTHism?
low PTH and serum calcium
75
What is pseudohypoPTHism?
Decreased response to PTH (labs show hypocalcemia with elevated PTH) presenting with short stature and short 4th and 5th digits (AD)
76
Insulin is secreted by ___ cells, which lie in the CENTER of islets of langerhans
Beta
77
T or F. Insulin promotes lipogenesis, protein synthesis, and glycogen synthesis
T. Glucose is taken up via GLUT4 receptors
78
Glucagon is secreted by what cells?
Alpha cells
79
What causes Type I DM?
Insulin deficiency due to **autoimmune destruction of beta cells by T lymphocytes** leading to a metabolic disorder marked by hyperglycemia
80
What are the classic findings of Type I DM?
Islet inflammation
Association with HLA-DR3 and HLA-DR4
AutoAbs aginst insulin (may be seen years before symptom onset)
81
How does type I DM present?
Manifests in childhood with clinical features of insulin deficiency, including:
Hyperglycemia
Weight loss, low muscle mass, and polyphagia (unopposed glucagon leads to gluconeogenesis, glycogenolysis, lipolysis)
Polyuria, polydipsia, and glycosuria
82
Type I DM carries the highest risk for what?
Diabetic ketoacidosis
83
Describe Diabetic ketoacidosis
Marked by excessive serum ketones that result in symptoms of **hyperglycemia (300+ mg/dL), anion gap metabolic acidosis, and hyperkalemia**
84
How does Diabetic ketoacidosis present?
Kussmaul respirations, dehydration, N/V, mental status change, and fruity smelling breath (due to acetone)
85
Diabetic ketoacidosis often is precipitates by what?
**Stress (e.g. infection)**- epinephrine stimulates glucagon secretion increasing lipolysis (along with gluconeogenesis and glycogenolysis). Lipolysis leads to increased FFAs, which are converted by the liver to ketone bodies
86
How is Diabetic ketoacidosis tx?
fluids (corrects dehydration from polyuria)
insulin
replacement of electrolytes (e.g. potassium)
87
What is Type II DM?
End-organ resistance to insulin leading to a mtabolic disorder marked by chronic hyperglycemia (strong genetic predisposition)
88
What is a classic biopsy finding of Type II DM?
Amyloid deposition in islets
89
How is Type II DM diagnosed?
Random glucose over 200 mg/dL
Fasting glucose over 126 mg/dL
Glucose tolerance test with serum glucose level over 200 mg/dL two hrs after glucose loading
90
Type II DM carries a high risk for what complication?
Hyperosmolar non-ketotic coma
91
What are some microscopic consequences of DM?
Noneymatic glucosylation of vascular BM (leads to atherosclerosis of medium and large vessels and its resultant complications including CV disease (leading cause of death), peripheral vascular neuropathy)
92
Non-enzymatic glycosylation of small vessels leads to what?
Hyaline arteriolsclerosis, esp in the kidneys Onion skinning) with preferential involvement of efferent arterioles leading to glomerular hyperfiltration with microalbuminuria that eventually progresses to nephrotic syndrome (**Kimmelsteil-Wilson nodules**)
93
Diabetes also leads to osmotic damage, with sequelae including:
Glucose entering Schwann cells, pericytes of retinal blood vessels, and the lens where Aldose reductase converts glucose to sorbitol, resulting in osmotic damage
## Footnote
**Leads to peripheral neuropathy, impotence, blindness, and cataracts**
94
What is the triad of MEN1?
Parathyroid hyperplasia
pituitary adenoma
pancreatic endocrine neoplasms
95
Describe the various pancreatic endocrine neoplasms
Insulinomas (present as episodic hypoglcemia with mental status chnages that are relived by glucose and diagnosed by decreased serum glucose levels (less than 50 mg/dL), elevated insulin, and elevated C-peptide)
Gastrinomas presenting as tx-resistant peptic ulcers (Zollinger-Ellison syndrome)
Somatostatinomas
VIPomas
96
How do Somatostatinomas present?
achlorhydria (due to inhibition of gastrin) and cholelithiasis with steatorrhea due to inhbition of cholecystokinin)
97
How might VIPomas present?
excessive vasoactive intestinal peptide leading to **watery diarrhea, hypokalemia, and achlorhydria**
98
What are the layers of the adrenal cortex?
Glomerulosa (mineralcorticoids like aldosterone)
Fasciculata (glucocorticoids like cortisol)
Reticularis (androgens like DHEA)
99
Cortical hormones are derived from \_\_\_\_\_
cholesterol
100
Describe the production of aldosterone
Cholesterol to pregnenolone via desmolase
pregnenolone to progesterone via 3B-HSD
progesterone to 11-Deoxycorticosterone via 21-OHase
11-Deoxycorticosterone to corticosterone via 11-OHase
corticosterone to aldosterone via aldo-synthase
101
Describe the production of cortisol
pregnenolone to 17-OH pregnenolone via 17-OHase
17-OH pregnenolone to 17-OH progesterone via 3B-HSD (or progesterone to 17-OH progesterone via 17-OHase)
17-OH progesterone to 11-deoxycortisol via 21-OHase
11-deoxycortisol to cortisol via 11-OHase
102
Describe hyperaldosteronism
Excessive aldosterone production classically presenting as HTN, hypokalemia, and metabolic acidosis because aldosterone inreased absorption of sodium (leading to HTN- no edema) and secretion of potassium and H+ ions in the distal tubule and CT
103
Primary hyperaldosteronism is usually due to what?
bilateral adrenal hyperplasia, **adrenal adenoma** (Conn Syndrome), and adrenal carcinoma (rare)
104
How is primary hyperaldosteronism tx?
Mineralcorticoid receptor antagonist (e.g. spironolactona or eplerenone) and adenomas are usually surgically resected
105
Secondary hyperaldosteronism is usally due to what?
Activation of the renin-angiotensin system (e.g. renovascular HTN or CHF)- will see high aldosterone AND renin (renin low in primary)
106
What causes familial hyperaldosteronism?
Overexpression of aldosterone synthase in the fasciculata (presents in children as HTN, hypokalemia, high aldosterone, and low renin)
107
How is familial hyperaldosteronism tx?
dexamethasone (confirmed with genetic testing)
108
What is Liddle Syndrome?
Mimics hyperaldosteronism due to decreased degradation of sodium channels (AD) in collecting tubules classically presenting as HTN, hypokalemia, and metabolic acidosis in a young pt.
Low aldosterone and renin
109
How is Liddle Syndrome tx?
K+-sparing diuretics (e.g. amiodarone or traimterene), which block tubular sodium channels **(spironolactoone is not effective)**
110
How does Cushing syndrome present?
Muscle weakness with thin extremities- cortisol breaks down muscle to produce AAs for gluconeogenesis)
Moon facies, buffalo hump, and truncal obesity- high insulin due to high glucose increases central fat storage
Abdominal striae- due to impaired collagen synthesis resulting in thinning of skin
HTN often with hypokalemia and metabolic alkalosis
Osteoporosis
Immune suppression
111
Why does Cushing cause HTN often with hypokalemia and metabolic alkalosis?
high cortisol increases sensitivity of peripheral vessels to catecholamines and **at very high-levels cortisol cross-reats with mineralcorticoid receptors**
112
How is Cushing syndrome diagnosed?
Based on 24 hr urine cortisol levels (increased), late night salivary cortsiol level (increased), and low-dose dexamthasone suppression test- low-dose dexamethasone suppresses cortisol in normal pts but fails to suppress cortiol in allcause of Cushing syndrome
113
How can you distinguish ACTH-dependent causes of Cushing syndrome from ACTH-independent causes?
Plasma ACTH
If ACTH-depdenent, next step is high-dose dexamethasone test
If ACTH-independent, next step is CT to look for an adrenal lesion
114
How does a high-dose dexamethasone test work?
Suppresses ACTH production by a pituitary adenoma (serum cortisol is lowered) but does not suppress ectopic ACTH production (serum cortisol remains high)
115
What are the four most common causes of Cushing Syndrome?
Exogenous glucocorticoids
ACTH-secreting pituitary adenoma (aka Cushing disease)
Ectopic ACTH secretion
Primary adrenal adenoma (10%), hyperplasia, or carcinoma
116
Describe Exogenous glucocorticoids as the cause of CD
cortisol: High
ACTH: low
Imaging: Bilateral adrenal atrophy
117
Describe ACTH-secreting pituitary adenomas as the cause of CD
Cortisol: High
Low dose dexamethasone: No suppression
ACTH: High
High dose dexamethasone: Suppression
Imaging: Bilateral adrenal hyperplasia
118
Describe Ectopic ACTH production as the cause of CD
Cortisol: High
Low dose dexamethasone: No suppression
ACTH: Very high (hyperpigmentation may be present)
High dose dexamethasone: No suppression
Imaging: Bilateral adrenal hyperplasia; possibly lung cancer
119
Describe Primary tumors as the cause of CD
Cortisol: High
Low dose dexamethasone: No suppression
ACTH: Low
Imaging: Adenoma/carcinoma with contralateral atrophy or bilateral nodular hyperplasia
120
What causes congenital aderenal hyperplasia?
Enzymatic defects (AR) in cortisol production with:
High ACTH due to decreased negative feedback (leas to bilateral adrenal hyperplasia)
Mineralcorticoids and androgens may be increased or decreased depending on enzyme defect
121
What is the most common cause of congenital adrenal hyperplasia?
21-hydroxylase deficiency (90%)
122
How does 21-hydroxylase deficiency present?
Aldosterone and cortisol low; steroidogenesis shifted toward androgens
Classic form presents in neonates as hyponatremia, hyperkalemia, and hypovolemia with life-threatening hypotension (due to salt-wasting) and clitoral enlargement
Nonclassic form presents later in life with androgen excess leading to precocious puberty (males) or hirsutism with menstrual irregularities (females)
123
What are some other common causes of congeital adrenal hyperplasia?
17-hydroxylase deficiency
11-hydroxylase deficiency
124
How does 11-hydroxylase deficiency present?
similar to 21-hydroxylase deficiency, but weak mineralocrticoids are increased leading to HTN with mild hypokalemia (renin and aldosterone are low)
125
How does 17-hydroxylase deficiency present?
Decreased cortisol and androgrens with increased mineralcorticoids leading to HTN and mild hypokalemia (renin and aldosterone are low), decreased androgens leads to primary amenorrhea and lack of pubci hair in feamels and pseudohermaphroditism in males
126
Screening for CAH involves serum 17-hydroyprogesterone levels. Explain
High in 21- and 11-hydroxylase deficiency
Low in 17-hydroylase deficiency
127
Chronic adrenal insufficiency is known as \_\_\_\_\_\_\_
Addison disease (due to progression destruction to the adrenal glands)
128
What are the most common causes of Addison disease?
Autoimmune destruction, TB, and metastatic carcinoma (e.g. lung)
129
How does Addison disease present?
Hypotension, hyponatremia, and hypovolemia, hyperkalemia, metabolic acidosis, weakness, hyperpigmentation, vomiting, and diarrhea
130
What is the adrenal medullar composed of?
Neural crest-derived chromaffin cells that produce epi and nor
131
What is a tumor of chromaffin cells?
Pheochromocytoma
132
Describe Pheochromocytomas
Episodic HTn, HA, paplitationa, tachycardia, and sweating
133
How are Pheochromocytomas diagnosed?
increased serum metanephrines and icnreased 24-hr urine vanillylmandelic acid and metanephrines
134
How are Pheochromocytomas tx?
Surgical resection (catecholamines may leak into the bloostream during resection, and phenoxybenzamine (irreversible a-blocker) is giving perioperatively to prevent a hypertensive crisis)
135
What is the rule of 10s of Pheochromocytomas?
10% are:
familial, malignant, bilateral, and located outside of the adrenal medulla (e.g. the bladder wall or organ of Zuckerkandl at the IMA root)
136
Pheochromocytomas are associated with what syndromes?
MEN 2A and 2B, von Hippel Lindau disease, and NF-1
