Chapter 15 Endocrine Flashcards
1
Q
What is the endocrine system, how does it function, and what controls it?
A
Group of glands that maintain body homeostasis. Functions by release of hormones that travel via blood to distant organs. “feedback” mechanisms control hormone release
2
Q
Where does the pituitary gland sit?
A
sella turcica
3
Q
What is a pituitary adenoma?
A
Benign tumor of anterior pituitary cells
4
Q
What are the two general categories of pituitary adenomas?
A
Functional and non-functional
5
Q
What to nonfunctional pituitary adenomas present with?
A
mass effect. Bitemporal hemianopsia occurs due to compression of the optic chiasm. Hypopituitarism occurs due to compression of normal pituitary tissue. Headache
6
Q
How do functional pituitary adenomas present?
A
present with features based on type of hormone produced
7
Q
How does a prolactinoma present?
A
as galactorrhea and amenorrhea (females) or as decreased libido and headache (males)
8
Q
What is the most common type of pituitary adenoma?
A
prolactinoma
9
Q
What is the treatment for a prolactinoma?
A
Dopamine agonists (e.g. bromocriptine or cabergoline) to suppress prolactin production (shrinks tumor) or surgery for larger lesions
10
Q
What does a GH cell adenoma cause in children?
A
Gigantism in children- increased linear bone growth (epiphyses are not fused)
11
Q
What does a GH cell adenoma cause in adults?
A
Acromegaly. Enlarged bones of the hands, feet, and jaw. Growth of visceral organs leading to dysfunction (e.g. cardiac failure). Enlarged tongue.
12
Q
What disease is often secondary to a GH cell adenoma?
A
Diabetes Mellitus (GH induces liver gluconeogenesis)
13
Q
How is a GH cell adenoma diagnosed?
A
by elevated GH and insulin growth factor 1 (IGF-1) levels along with lack of GH suppression by oral glucose (should suppress GH)
14
Q
What effect does GH have on blood glucose levels?
A
It inhibits glucose uptake into cells
15
Q
What does treatment of a GH cell adenoma involve?
A
Octreotide (somatostatin analog that suppresses GH release), GH receptor antagonists, or surgery
16
Q
What do ACTH cell adenomas secrete and what do they lead to?
A
secrete ACTH leading to Cushing syndrome
17
Q
How common are TSH cell, LH producing, and FSH producing adenomas?
A
They occur but are rare.
18
Q
What is hypopituitarism and at what point do clinical symptoms become apparent?
A
Insufficient production of hormones by the anterior pituitary gland: symptoms arise when >75% of the pituitary parenchyma is lost
19
Q
Name three causes of hypopituitarism?
A
1 Pituitary adenomas(adults) or craniopharyngioma(children)
2 Sheehan syndrome
3 Empty sella syndrome
20
Q
How do pituitary adenomas and craniopharyngiomas cause hypopituitarism?
A
Mass effect or pituitary apoplexy (bleeding into an adenoma)
21
Q
What is Sheehan syndrome? How does it arise and present?
A
Pregnancy related infarction of the pituitary gland. gland doubles in size during pregnancy, but blood supply does not increase significantly; blood loss during parturition precipitates infarction. Presents as poor lactation, loss of pubic hair (dependent on androgens thus LH), and fatigue.
22
Q
What is empty sella syndrome?
A
Congenital defect of the sella. Herniation of the arachnoid and CSF into the sella compresses and destroys the pituitary gland. Pituitary gland is “absent” (empty sella) on imaging.
23
Q
What two hormones are released from the posterior pituitary and where are they produced?
A
ADH and oxytocin are made in the hypothalamus and then transported via axons to the posterior pituitary for release.
24
Q
What does oxytocin do?
A
Mediates uterine contraction during labor and release of breast milk (let-down) in lactating mothers
25
What is the defect in central diabetes insipidus?
ADH deficiency
26
What are some causes of central diabetes insipidus?
hypothalamic or posterior pituitary pathology (e.g. tumor, trauma, infection, or inflammation)
27
What are the clinical features of central diabetes insipidus based on and what are they?
Based on loss of free water.
1 polyuria and polydipsia with risk of life threatening dehydration
2 Hypernatremia and high serum osmolarity
3 low urine osmolarity and specific gravity
28
What is a clinical test for central diabetes insipidus?
Water deprivation test fails to increase urine osmolarity
29
What does treatment of central diabetes insipidus involve?
Desmopressin (ADH analog)
30
What is nephorgenic diabetes insipidus and what is it due to?
Impaired renal response to ADH. Due to inherited mutations or drugs (e.g. lithium and demeclocycline)
31
What are the clinical features of nephrogenic diabetes insipidus?
Clinical feature are similar to central diabetes insipidus, but there is no response to desmopressin
32
What is syndrome of inappropriate ADH (SIADH) secretion and what is it usually due to (be specific)?
Excessive ADH secretion. Most often due to ectopic production (e.g. small cell carcinoma of the lung); other causes include CNS trauma, pulmonary infection, and drugs (e.g. cyclophosphamide)
33
What are the clinical features of SIADH based on and what are they?
based on retention of free water.
1 Hyponatremia and low serum osmolality.
2 Mental status changes and seizures - hyponatremia leads to neuronal swelling and cerebral edema
34
What is the treatment for SIADH?
free water restriction or democlocycline (blocks effect of ADH)
35
What is a thyroglossal duct cyst?
cystic dilation of thyroglossal duct remnant
36
Describe the basic embryology of the thyroid gland?
Thyroid develops at the base of the tongue and then travels along the thyroglossal duct to the anterior neck. Thyroglossal duct normally involutes: a persistent duct, however, may undergo cystic dilation.
37
How does a thyroglossal duct cyst present?
anterior neck mass
38
What is a lingual thyroid, how does it present?
Persistence of thyroid at the base of the tongue. Presents as a tongue mass.
39
What is elevated in hyperthyroidism and what 2 major systemic effects does this have and what are each due to?
Increased level of circulating thyroid hormone. Increases basal metabolic rate (due to increases synthesis of Na/K ATPase). Increased sympathetic nervous system activity (due to increases expression of Beta 1 adrenergic receptors)
40
List 12 clinical features of hyperthyroidism? hahaha good luck
1 Weight loss despite increased appetite
2 Heat intolerance and sweating
3 Tachycardia with increased CO
4 Arrhythmia (e.g. atrial fibrillation), especially in the elderly
5 Tremor, anxiety, insomnia, and heightened emotions
6 Staring gaze with lid lag
7 Diarrhea with malabsorption
8 Oligomenorrhea
9 Bone resorption with hypercalcemia (risk for osteoporosis)
10 Decreased muscle mass with weakness
11 Hypocholesteremia
12 Hyperglycemia (due to gluconeogenesis and glycogenolysis)
41
What is graves disease and what is it caused by? Who does it classically occur in?
Autoantibody IgG that stimulates TSH receptor (type II hypersensitivity). Leads to increased synthesis and release of thyroid hormone. Classically occurs in women of childbearing age (20-40)
42
What is the most common cause of hyperthyroidism?
Graves Disease
43
What are 3 clinical features of Graves disease?
1 Hyperthyroidism
2 Diffuse Goiter
3 Exopthalmos and pretibial myxedema (dough like consistancy)
44
What causes goiter formation in Graves disease?
constant TSH stimulation leads to thyroid hyperplasia and hypertrophy
45
What causes exopthalmos and pretibial myxedema in Graves disease?
Fibroblasts behind the orbit and overlying the shin express the TSH receptor. TSH activation results in glycosaminoglycan (Chondroitin sulfate and hyaluronic acid) buildup, inflammation , fibrosis, and edema leading to exopthalmos and pretibial myxedema.
46
What is seen on histology in Graves disease?
irregular follicles with scalloped colloid and chronic inflammation
47
What are the laboratory findings in Graves Disease?
1 Increase total and free T4; decreased TSH (Free T3 down-regulates TRH receptors in the anterior pituitary to decrease TSH release)
2 Hypocholesterolemia
3 Increases serum glucose
48
What does treatment of graces disease involve?
Beta blockers, thioamide, and radioiodine ablation.
49
What is a potentially fatal complication of hyperthyroidism?
Thyroid storm
50
What is thyroid storm due to?
Elevated catecholamines and massive hormone excess, usually in response to stress (e.g. surgery or childbirth)
51
How does thyroid storm present?
Presents as arrhythmia, hyperthermia, and vomiting with hypovolemic shock
52
What is the treatment for thyroid storm?
propylthiouracil (PTU), beta blockers and steroids.
53
What does PTU do?
Inhibits peroxidase mediated oxidation, organification, and coupling steps of thyroid synthesis, as well as peripheral conversion of T4 to T3
54
What is a multinodular goiter? what is it due to?
Enlarged thyroid gland with multiple nodules. due to relative iodine deficiency
55
Is a multinodular goiter usually toxic or non-toxic?
Usually non-toxic (euthyroid)
56
How can a multinodular goiter become toxic?
Rarely, regions become TSH-independent leading to T4 release and hyperthyroidism ('toxic goiter')
57
What is Cretinism?
hypothyroidism in neonates and infants
58
What is cretinism characterized by?
Mental retardation, short stature with skeletal abnormalities, coarse facial features, enlarged tongue, and umbilical hernia. TH is required for normal brain and skeletal development
59
What are some causes of Cretinism? 4
maternal hypothyroidism during early pregnancy, thyroid agenesis, dyshormonogenetic goiter, and iodine deficiency.
60
What is dyshormonogenetic goiter due to?
A congenital defect in thyroid hormone production; most commonly involves thyroid peroxidase
61
What is Myxedema? (the disease)
Hypothyroidism in older children or adults.
62
What are the clinical features of myxedema based on?
decreased basal metabolic rate and decreased sympathetic nervous system activity
63
What are 9 symptoms of myxedema?
```
1 Myxedema
2 Weight gain despite normal appetite
3 slowing of mental activity
4 muscle weakness
5 cold intolerance with decreased sweating
6 bradycardia with decreased cardiac output, leading to shortness of breath and fatigue
7 oligomenorrhea
8 hypercholesteremia
9 Constipation
```
64
What is myxedema (the symptom)?
Accumulation of glycosaminoglycans in the skin and soft tissue; results in a DEEPENING VOICE and LARGE TONGUE
65
What is Hashimoto Thyroiditis? What is it associated with
Autoimmune destruction of the thyroid gland; associated with HLA-DR5
66
What is the most common cause of hypothyrodism in regions where iodine levels are adequate?
Hashimoto Thyroiditis
67
What are 3 clinical features of Hashimoto Thydoiditis?
1 Initially may present as hyperthyroidism (due to follicle damage and leakage of TH into blood)
2 Progresses to hypothyroidism; with decreased T4 and increased TSH
3 Antithyroglobulin and antithyroid peroxidase antibodies are often present (sign of thyroid damage); this do not mediate the disease but are simply markers
68
What can be seen on histology in Hashimoto Thyroiditis?
Chronic inflammation with germinal centers and Hurthle cells (eosinophillic metaplasia of cells that line follicles )
69
What cancer are patients with Hashimoto Thyroiditis at higher risk for? how would this progression present?
Increased risk for B-cell (marginal zone) lymphoma; presents as an enlarging thyroid gland late in disease course
70
What is Subacute Granulomatous (De Quervain) Thyroiditis?
Granulomatous thyroiditis that follows a viral infection
71
How does Subacute Granulomatous (De Quervain) Thyroiditis present?
as a tender thyroid in a young woman with transient hyperthyroidism
72
Describe the progression of Subacute Granulomatous (De Quervain) Thyroiditis?
Self-limited; rarely (15%) may progress to hypothyroidism but never to hyperthyroidism
73
What is Riedel Fibrosing Thyroiditis?
Chronic inflammation with extensive fibrosis of the thyroid gland
74
How does Riedel Fibrosing Thyroiditis present?
As hypothyroidism with a "hard as wood", nontender thyroid gland. Fibrosis may extend to involve local structures (e.g. airway)
75
What does Riedel Fibrosing thyroiditis resemble clinically? how are they differentiated?
mimics anaplastic carcinoma, but patients are younger (40s as compared to 80s) and malignant cells are absent
76
How does thyroid neoplasia typically present, are they more likely to me benign or malignant?
Presents as a distinct, solitary nodule. More likely to be benign
77
What is a useful diagnostic study to further characterize thyroid nodules?
131 Iodine radioactive uptake studies
78
What does increased or decreased uptake of 131 Iodine indicate? (thyroid study)
Increased uptake (hot nodule) is seen in graves disease or nodular goiter. Decreased uptake (cold nodule) is seen in adenoma and carcinoma; often warrants biopsy
79
How is a biopsy of the thyroid performed?
Fine Needle Aspirate; very bloody organ and you dont want to disseminate.
80
What is follicular adenoma?
Benign proliferation of follicles surrounded by a fibrous capsule
81
Are Follicular adenomas functional or nonfunctional?
Usually nonfunctional; less commonly, may secrete thyroid hormone
82
What is the most common type of thyroid carcinoma?
papillary carcinoma (80%)
83
What is a major risk factor for papillary carcinoma of the thyroid?
Exposure to ionizing radiation in childhood is a major risk factor
84
What is papillary carcinoma of the thyroid composed of?
Comprised of papillae lined by cells with clear, 'Orphan Annie eye' nuclei and nuclear grooves; papillae are often associated with psammoma bodies
85
Where does papillary carcinoma of the thyroid often spread to and what is the general prognosis?
cervical lymph nodes, but prognosis is excellent
86
What designates an 'Orphan Annie eye' nuclei?
White clearing within the nucleus
87
What is follicular carcinoma of the thyroid?
Malignant proliferation of follicles surrounded by a fibrous capsule with invasion through the capsule
88
What helps differentiate follicular carcinoma from follicular adenoma?
Invasion through the capsule in carcinoma
89
Can FNA differentiate between follicular adenoma and carcinoma of the thyroid? why?
No it cannot. FNA only examines the cells and not the capsule, the entire capsule must be examined.
90
How do metastases of follicular carcinoma of the thyroid spread?
hematogeneously
91
What is medullary carcinoma of the thyroid?
Malignant proliferation of parafollicular C cells; comprises 5% of thyroid carcinomas
92
What are C cells of the thyroid?
C cell are neuroendocrine cells that secrete calcitonin
93
Where does calcitonin do?
Lowers serum calcium by increasing renal calcium excretion but is inactive at normal physiologic levels
94
What can high levels of calcitonin produced by a tumor cause?
hypocalcemia
95
What does calcitonin often deposit?
in the tumor as amyloid
96
What does biopsy of medullary carcinoma of the thyroid reveal?
Sheets of malignant cells in an amyloid stroma
97
What are familial cases of medullary carcinoma of the thyroid often due to?
multiple endocrine neoplasia (MEN) 2A and 2B, which are associated with mutations in the RET oncogene
98
Describe what MEN 2A and 2B results in?
MEN 2 results in medullary carcinoma, pheochromocytoma, and parathyroid adenomas (2A) or ganglioneuromas of the oral mucosa (2B)
99
What does detection of a RET mutation warrant?
Prophylactic thyroidectomy
100
What is anaplastic carcinoma of the thyroid? who is it usually seen in?
Undifferentiated malignant tumor of the thyroid; usually seen in elderly
101
What are the clinical features and prognosis of Anaplastic carcinoma of the thyroid?
Often invades local structures, leading to dysphagia or respiratory compromise. Poor prognosis
102
What is the function of the Chief cells of the parathyroid glands?
Chief cells regulate serum free (ionized) calcium via parathyroid hormone (PTH)
103
What are 3 functions of PTH?
1 Increases bone osteoclast activity, releasing calcium and phosphate
2 Increases small bowel absorption of calcium and phosphate (indirectly by activating vitamin D)
3 Increases renal calcium reabsorption (distal tubule) and decreased phosphate reabsorption (proximal tubule)
104
Which bone cell has the PTH receptor?
OSTEOBLAST
105
What provides negative feedback to decrease PTH secretion?
Serum ionized calcium
106
What is primary hyperparathyroidism?
Excess PTH due to a disorder of the parathyroid gland itself
107
What is the most common cause of primary hyperparathyroidism and what are two other causes?
Most common is parathyroid adenoma (>80%), sporadic parathyroid hyperplasia and parathyroid carcinoma are less common causes
108
What is parathyroid adenoma, is it unilateral or bilateral?
Benign neoplasm, usually involving one gland
109
What are the symptoms of parathyroid adenoma?
Most often results in asymptomatic hypercalcemia; however, may present with consequences of increased PTH and hypercalcemia
110
What are 5 consequences of increased PTH and hypercalcemia?
1 Nephorlithiasis (calcium oxalate stones)
2 Nephocalcinosis - metastatic calcification of renal tubules, potentially leading to renal insufficiency and polyuria
3 CNS disturbances (e.g. depression and seizures)
4 Constipation, peptic ulcer disease, and acute pancreatitis (PTH causes release of pancreatic enzymes)
5 Osteitis fibrosa cystica - resorption of bone leading to fibrosis and cystic spaces
111
What do the following lab values show in Primary Hyperparathyroidism?
PTH, calcium, phosphate, urinary cAMP, alkaline phosphatase
increased PTH, calcium, urinary cAMP, and alkaline phosphatase.
decreased phosphate
112
What does treatment of primary hyperparathyroidism involve?
surgical removal of the affected gland.
113
What type of G protein is the PTH receptor coupled to and what is the secondary messenger?
Gs; cAMP
114
What is secondary hyperparathyroidism?
Excess production of PTH due to a disease process extrinsic to the parathyroid gland.
115
What is the most common cause of secondary hyperparathyroidism?
Chronic renal failure
116
Describe how chronic renal failure leads to secondary hyperparathyroidism?
1 Renal insufficiency leads to decreased phosphate excretion.
2 Increased serum phosphate binds free calcium
3 decreased free calcium stimulates all four parathyroid glands
4 increased PRH leads to bone resorption (contributing to renal osteodystrophy)
117
What do the following lab values show in secondary hyperparathyroidism? PTH, calcium, phosphate, alkaline phosphatase?
Increased PTH, Phosphate, alkaline Phosphatase
| decreased Calcium
118
What is the defining feature of hypoparathyroidism?
Low PTH
119
What are 3 causes of hypoparathyroidism?
autoimmune damage to the parathyroids, surgical excision, and DiGeorge Syndrome (failure to develop 3rd and 4th pharyngeal pouch which includes parathyroid)
120
What are symptoms of hypoparathyroidism related to?
low calcium
121
What are 2 symptoms of hypoparathyroidism?
1 Numbness and tingling (particularly circumoral [around lips])
2 Muscle spasms (tetany) - may be elicited with filling of a blood pressure cuff (trousseau sign) or tapping on the facial nerve (Chvostek sign)
122
What doe the following lab values show in hypoparathyroidism? PTH and calcium?
decreased PTH and calcium
123
What is pseudohypoparathyroidism due to? what does the PTH level shoe
End organ resistance to PTH due to defects in Gs proteins. PTH is increased
124
What is the AD form of pseudohypoparathyroidism associated with?
Short stature and short 4th and 5th digits
125
Describe the structural organization of the endocrine pancreas?
It is composed of clusters of cells termed islets of Langerhans. A single islet consists of multiple cell types, each producing one type of hormone.
126
What pancreas cell secretes insulin and where is it located within the islet?
Insulin is secreted by beta cells, which lie in the center of the islets.
127
What is insulin and what does it do in the body.
Major anabolic hormone; upregulates insulin dependent glucose transporter protein (GLUT4) on skeletal muscle and adipose tissue (glucose uptake by GLUT4 decreases serum glucose)
128
What does increased glucose uptake by tissues lead to?
increased glycogen synthesis, protein synthesis, and lipognesis.
129
What cell secretes glucagon and what is glucagon's function?
Glucagon is secreted by alpha cells; it opposes insulin in order to increase blood glucose levels (e.g. in states of fasting) via glycogenolysis and lipolysis
130
What is Type 1 DM?
Insulin deficiency leading to a metabolic disorder characterized by hyperglycemia.
131
What is Type 1 DM due to?
Due to autoimmune destruction of beta cells by T lymphocytes
132
What is autoimmune destruction of beta cells characterized by in DM1?
inflammation of islets
133
What genetic markers is DM1 associated with?
HLA-DR3 and HLA-DR4
134
What other types of autoantibodies may be present in DM1?
Autoantibodies agains insulin are often present (sign of damage) and may be seen years before clinical disease develops
135
When does DM1 manifest and what are the clinical features associated with?
Manifests in childhood with clinical features of insulin deficiency
136
What are 3 major features of DM1
1 High serum glucose
2 Weight loss, low muscle mass, and polyphagia -
3 Polyuria, polydipsia, and glycosuria
137
What causes weight loss, low muscle mass and polyphagia in DM1?
unopposed glucagon leads to gluconeogenesis, glycogenolysis and lipolysis, which further exacerbates hyperglycemia
138
What causes high serum glucose in DM1?
- lack of insulin leads to decreased glucose uptake by fat and skeletal muscle
139
What causes polyuria, polydipsia, and glycosuria in DM1?
Hyperglycemia exceeds renal ability to resorb glucose; excess filtered glucose leads to osmotic diuresis
140
What does treatment of DM1 involve?
Lifelong insulin
141
What is diabetic ketoacidosis characterized by?
excessive serum ketones
142
What is often a triggering factor for diabetic ketoacidosis and how does it happen
Often arises with stress (e.g. infection); epinepherine stimulates glucagon secretion increasing lipolysis (along with gluconeogenesis and glycogenolysis)
143
How does increases lipolysis lead to diabetic ketoacidosis?
Increases lipolysis leads to increases free fatty acids. Liver converts free fatty acids to ketone bodies
144
What are the two main ketone bodies present in diabetic ketoacidosis?
Beta-hydroxybutyric acid and acetoacetic acid
145
What are 3 things that diabetic ketoacidosis results in?
```
1 Hyperglycemis (>300mg/dL)
2 Anion gap metabolic acidosis
3 Hyperkalemia
```
146
How does diabetic ketoacidosis present (6)?
```
1 Kussmaul Respirations
2 Dehydration
3 Nausea
4 Vomiting
5 Mental status changes
6 fruity smelling breath (due to acetone)
```
147
What does treatment of diabetic ketoacidosis include?
fluids (corrects dehydration from polyuria), insulin, and replacement of electrolytes (e.g. potassium)
148
Name two mechanisms which lead to hyperkalemia in diabetic ketoacidosis? What happens to total K+?
1 insulin drives K+ into cells, no insulin results in increased extracellular K+
2 Acidosis- buffering mechanism is H+/K+ exchange, H+ goes into cell and K+ comes out
However the K+ is lost in the urine and total body K+ will be LOW
149
What is DM 2?
End-organ insulin resistance leading to a metabolic disorder characterized by hyperglycemia
150
What is more common, type 1 or type 2 DM?
type 2 (90%)
151
How does obesity contribute to type 2 DM?
Obesity leads to decreased numbers of insulin receptors
152
Which has a stronger genetic predisposition, type 1 or type 2 DM?
type 2
153
Describe the insulin levels during the progression of type 2 DM?
Insulin levels are increased early in the disease, but later, insulin deficiency develops due to beta cell exhaustion
154
What is seen on histology in late type 2 DM?
reveals amyloid deposition in the islets
155
What are the clinical features of type 2 DM? (3)
polyuria, polydipsia, and hyperglycemia, but disease is often clinically silent
156
How is the diagnosis of type 2 DM made?
By measuring glucose levels (normal is 70-120)
Random glucose > 200 mg/dL
Fasting glucose > 126 mg/dL
Glucose tolerance test with a serum glucose level > 200 mg/dL two hours after glucose loading
157
What does treatment of type 2 DM involve?
weight loss (diet and exercise) initially; may require drug therapy to counter insulin resistance (e.g. sulfonylureas or metformin) or exogenous insulin after exhaustion of beta cells.
158
What life threatening situation are type 2 diabetics at risk for and what happens in this situation?
Hyperosmolar non-ketotic coma. High glucose (> 500 mg/dL) leads to life threatening diuresis with hypotension and coma
159
Are type 2 diabetics at risk for keto acidosis?
no because low levels of circulating insulin are sufficient enough to counter the effects of glucagon
160
What leads to vascular damage in diabetes? (general process)
Non-enzymatic glycosylation of vascular basement membranes
161
What does NEG of large and medium sized vessels in diabetes lead to?
leads to atherosclerosis and its resultant complications
162
What is the leading cause of death among diabetic patients?
Cardiovascular disease
163
What is the leading cause of non-traumatic amputations in diabetics?
Peripheral vascular disease
164
What does NEG of small vessels in diabetes lead to?
hyaline arteriolosclerosis
165
What does NEG of renal arterioles lead to?
Involvement of renal arterioles leads to glomeruloscelrosis, resulting in small, scarred kidneys with a granular surface.
166
Which renal arteriole is preferentially affected by NEG and what does this result in?
Preferential involvement of efferent arterioles leads to glomerular hyperfiltration injury with microalbuminuria that eventually progresses to nephrotic syndrome; characterized by Kimmelstiel-Wilson nodules in glomeruli
167
What does NEG of hemoglobin cause?
produces glycated hemoglobin (HbA1c), a marker of glycemia control
168
Describe the progression of osmotic damage in diabetes?
1 Glucose freely enters into schwann cells, pericytes of retinal blood vessels, and the lens.
2 Aldose reductase converts glucose to sorbitol, resulting in osmotic damage. (pericytes die, weakened wall, aneurysm, rupture)
3 Leads to peripheral neuropathy, impotence, blindness, and cataracts. Diabetes is the leading cause of blindness in the developed world
169
What are pancreatic endocrine neoplasms and what percent of pancreatic neoplasms do the represent?
tumor of islet cells: account for <5% of pancreatic neoplams
170
What are pancreatic endocrine neoplasms often associated with?
Often a component of MEN 1 along with parathyroid hyperplasia and pituitary adenoma
171
how doe insulinomas present?
Present as episodic hypoglycemia with mental status changes that are relieved by administration of glucose
172
What lab values are used to diagnose an insulinoma?
decreased serum glucose (usually < 50 mg/dL), increased insulin, and increased C peptide
173
What do gastinomas cause?
parietal cells to produce excess acid
174
how doe gastrinomas present?
as treatment resistant peptic ulcers (Zollinger-Ellison syndrome); ulcers may be multiple and can extend into the jejunum
175
How do somatostatinomas present?
presents with achlorhydia (due to inhibition of gastrin) and cholelithiasis with steatorrhea (due to inhibition of cholecystokinin
176
What do VIPomas do and what do they lead to?
They secrete excessive vasoactive intestinal peptide leading to watery diarrhea, hypokalemia, and achlorhydia
177
What are the 3 layers of the adrenal cortex and what hormones do they secrete?
Glomerulosa produces mineralocorticoids (aldosterone)
Fasciculata produces glucocorticoids (Cortisol)
Reticularis produces androgens (DHEA)
178
What are adrenal cortical hormones derived from?
cholesterol
179
How does hyperaldosteronism classically present?
HTN, hypokalemia, and metabolic alkalosis
180
What effects does aldosterone have on the kidney tubules and what does this lead to?
Aldosterone increases absorption of sodium and secretion of potassium and hydrogen ions in the distal tubule and collecting duct. Increased sodium expands plasma volume leading to hypertension. Edema is often absent, however, due to aldosterone escape (escape from the sodium retaining effects of excess aldosterone by volume and/or pressure natriuresis)
181
What is the most common cause of primary hyperaldosteronism and what are two other less common causes?
most common is bilateral adrenal hyperplasia. adrenal adenoma (conn syndrome) and adrenal carcinoma (rare) are less common
182
Describe the levels of aldosterone and renin in primary hyperaldosteronism?
High aldosterone and low renin
183
What is the first line treatment for primary hyperaldosteronism?
mineralcorticoid receptor antagonists (e.g. spironolactone or eplerenone); adenomas are usually surgically resected
184
What is secondary hyperaldosternonism seen with? (give example in older men and women)
seen with activation of the renin-angiotensin system (e.g. renovascular HTN or CHF) Fibromuscular dysplasia in young women or atherosclerosis in older men
185
What is familial hyperaldosteronism due to? how common is it?
Due to glucocorticoid remediable aldosteronism. this is rare
186
Describe the pathogenesis of familial hyperaldosteronism?
aberrant expression (AD) of aldosterone synthase in the fasciculata
187
How does familial hyperaldosteronism present?
HTN, hypokalemia(+/-), and high aldosterone, and low renin
188
What is the treatment of familial hyperaldosteronism? how is the diagnoses confirmed?
Responds to decamethasone, confirmed with genetic testing
189
What syndrome can mimic hyperaldosteronism?
Liddle syndrome
190
What happens in liddle syndrome?
decreased degredation of sodium channels (AD) in collecting tubules
191
How does liddle syndrome classically present?
HTN, hypokalemia, and metabolic alkalosis in a young patient
192
Describe the aldosterone and renin levels in Liddle syndrome?
Low aldosterone and low renin
193
What is treatment of Liddle syndrome?
potassium sparing diuretics (e.g. amiloride or triamterene), which block tubular sodium channels; spironolactone is not effective
194
What are 6 features of hypercortisolism (Cushing syndrome)?
1 muscle weakness with thin extremities - cortisol breaks down muscle to produce amino acids for gluconeogenesis
2 Moon facies, buffalo hump, and truncal obesity - high insulin (due to high glucose ) increases storage of fat centrally
3 abdominal striae - due to impaired collagen synthesis resulting in thinning of skin
4 HTN often with hypokalemia and metabolic acidosis. (see additonal Q)
5 osteoporosis
6 immune suppression
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How does high cortisol cause hypertension?
1 increases the sensitivity of peripheral vessels to catecholamines by increasing alpha 1 receptors
2 At very high levels, cortisol cross-reacts with mineral corticoid receptors (aldosterone is not increased)
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How does high cortisol cause immune suppression? (3)
1 inhibits PLA2 which inhibits the production of arachidonic acid and its biproducts
2 Inhibits IL-2 which is an important T cell growth factor
3 Inhibits the release of histamine from mast cells which inhibits vasodilation and vascular permeability
197
What two forms of Cushing syndrome are important to distinguish when making a choice for treatment and what is the treatment of each?
ACTH independent - next step is CT to look for an adrenal lesion
ACTH dependent, next step is high dose dexamethasone test
Plasma ACTH determines between the two
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What does the dexamethasone test help differentiate in cushing syndrome?
High dose dexamethasone suppresses ACTH production by a pituitary adenoma (serum cortisol is lowered) but does not suppress ectopic ACTH production (serum cortisol remains high)
199
Name four causes of cushing syndrome? What is the cortisol level in each?
1 Exogenous corticosteroids
2 Primary adrenal adenoma, hyperplasia, or carcinoma
3 ACTH secreting pituitary adenoma
4 Paraneoplastic ACTH secretion
ALL have high cortisol
200
What is congenital adrenal hyperplasia characterized by and what is its inheritance pattern? Describe the pathogenesis?
Characterized by enzymatic defects (AR) in cortisol production. High ACTH (due to decreased negative feedback leads to bilateral adrenal hyperplasia. Mineralcorticoids and androgens may be increased or decreased depending on the enzyme defect
201
What is the most common cause of congenital adrenal hyperplasia?
21-hydroxylase deficiency (90%)
202
What does 21-hydroxylase deficiency lead to/ how does it present (classic and nonclassic)
ALdosterone and cortisol are decreased; steroidogenesis is shunted towards androgens. Classic form presents in neonates as hyponatremia, hyperkalemia, and hypovolemia with life threatening hypotension (due to salt wasting); females have clitoral enlargement (genital ambiguity). Nonclassic form presents later in life with androgen excess leading to precocious puberty (males) or hirsutism with menstual irregularities (females)
203
Describe the changes caused by 11 hydroxylase deficiency? symptoms, renin aldosterone levels?
11-hydroxylase deficiency is biochemically similar to 21 hydroxylase deficiency, but weak mineralcorticoids (DOC) are increased. Leads to hypertention (sodium retention) with mild hypokalemia. Renin and aldosterone are low
204
If you are given a classic history of 21 hydroxylase deficiency but without salt wasting, hyperkalemia and hypovolemia, what is the dx?
11 hydroxylase deficiency
205
What does 17 hydroxylase deficiency lead to?
leads to decreased cortisol and androgens. Weak mineralcorticoids (DOC) are increased leading to HTN and mild hypokalemia; renin and aldosterone are low. Decreased androgens (adrenal and gonads) lead to primary amenorrhea and lack of pubic hair in females or pseudohermaphroditism in males
206
What does screening for CAH involve? What doe the results indicate?
Screening involves serum 17-hydroxyprogesterone levels. Increased levels are seen in 21 and 11 hydroxylase deficiency. Decreased levels are seen in 17 hydroxylase deficiency.
207
What is the treatment for CAH?
glucocorticoids; mineralocorticoids (21 hydroxylase deficiency) or sex steroids (17 hydroxylase deficiency) may also be needed
208
What does acute adrenal insufficiency most commonly arise secondarily to and how does it present?
Secondary to abrupt withdrawal of glucocorticoids. Presents as weakness and hypotension (shock)
209
What is Waterhous-Friderichsen syndrome and what is it characterized by?
Classic cause of acute adrenal insufficiency. Characterized by hemorrhagic necrosis of the adrenal glands, classically due to DIC in young children with N. meningitidis infection. lack of cortisol exacerbates hypotension, often leading to death.
210
What is chronic adrenal insufficiency called, and what is it due to?
Addison disease, due to progressive destruction of the adrenal glands
211
Name 3 common causes of chronic adrenal insufficiency?
Autoimmune destruction (most common cause in the West), TB (most common cause in the developing world), and metastatic carcinoma (e.g. from the LUNG)
212
What are the clinical features of chronic adrenal insufficiency?
Hypotension, hyponatremia, hypovolemia, hyperkalemia, metabolic acidosis, weakness, hyperpigmentation (very high ACTH stimulates melanocytes POMC derivative) vomiting, and diarrhea.
213
What helps distinguish primary from secondary adrenal insufficiency?
Hyperpigmentation and hyperkalemia
214
What cells make up the adrenal medulla?
composed of neural crest derived chromaffin cells
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What is the main function of the adrenal medulla?
main physiologic source of catecholamines (epi and norepi)
216
What is pheochromocytoma?
Tumor of chromaffin cells
217
What are the clinical features of a pheochromocytoma and what are they?
Clinical features are due to increased serum catecholamines and include; episodic HTN, HA, palpitations, tachycardia, and sweating
218
How is a pheochromocytoma diagnosed?
By increased serum metanephrines and increased 24-hr urine metanephrines and vanillymandelic acid.
219
What is the treatment of a pheochromocytoma? describe what is done before treament?
Surgical excision. Chatecholamines may leak into the bloodstream upon manipulation of the tumor. Phenozybenzamine (irreversible alpha blocker) is administered perioperatively to prevent a hypertensive crisis
220
What is the rule of 10's with pheochromocytomas?
10% bilateral, 10% familial, 10% malignant, 10% located outside the adrenal medulla (e.g. bladder [episodic HTN during urination] or organ of Zuckerlandl at the IMA root)
221
What are pheochromocytomas associated with?
Associated with MEN 2A and 2B, von-hippel lindau disease, and NF type 1
222
What are the three main risks of von hippel lindau disease?
1 hemangioblastoma of cerebellum
2 RCC
3 pheochromocytoma
223
What color is a pheochromocytoma?
Brown tumor; same color as adrenal medulla
224
Describe the size of the adrenal glands in cushing sydrome due to exogenous glucocorticoids?
both small
225
Describe the size of the adrenal glands in cushing sydrome due to ACTH secreting pituitary adenoma?
Both big
226
Describe the size of the adrenal glands in cushing sydrome due to ectopic ACTH secretion?
Both big
227
Describe the size of the adrenal glands in cushing sydrome due to primary adrenal adenoma, hyperplasia, carcinoma?
One big one small
228
Describe the level of ACTH in cushing syndrome due to exogneous glucocorticoids?
Low
229
Describe the level of ACTH in cushing syndrome due to ACTH secreting pituitary adenoma?
High; androgen excess may be present
230
Describe the level of ACTH in cushing syndrome due to ectopic ACTH secretion?
Very high; androgen excess and hyperpigmentation may be present
231
Describe the level of ACTH in cushing syndrome due to Primary adrenal adenoma, hyperplasia, or carcinoma?
Low
232
Do any of the cuases of cushing syndrome respond to low dose dexamethasone?
no, non show suppression
233
How does cushing sydrome due to ACTH secreting pituitary adenoma and extopic ACTH secretion respond to high dose dexamethason?
ACTH secreting pituitary adenoma shows suppression.
| Ectopic ACTH secretion with show no suppresion.
234
Describe the imaging findings in cushing syndrome due to exogenous glucocorticoids?
Bilateral adrenal atrophy. Cortisol shuts down ACTH
235
Describe the imaging findings in cushing syndrome due to ACTH secreting pituitary adenoma?
Bilateral adrenal hyperplasia; pituitary adenoma
236
Describe the imaging findings in cushing syndrome due to ectopic ACTH secretion?
Bilateral adrenal hyperplasia; ectopic source of ACTH (e.g. small cell carcinoma or carcinoid)
237
Describe the imaging findings in cushing syndrome due to primary adrenal adenoma, hyperplasia, or carcinoma?
Adenoma/ carcinoma with contralateral atrophy or bilateral nodular hyperplasia.
