Chapter 19 Flashcards
1
Q
What are some diseases of the Posterior pituitary?
A
Abnormal secretion of antidiuretic hormone (ADH or Vasopressin)
Insufficient hormonal carrier proteins in plasma
2
Q
Reduced secreteion of ADH from posterior pituitary causes?
A
Water excretion and ECF hyperosmolarity
3
Q
Excess secretion of ADH from posterior pituitary causes?
A
Water reabsorption and hypoosmolarity
4
Q
What does ADH act on?
A
Kidneys
5
Q
What is syndrome of inappropriate antidiuretic hormone (SIADH)?
A
Occurs when high ADH levels are present in absence of normal physiological stimuli for its release
6
Q
What are some common causes of SIADH?
A
Ectopic secretion of ADH by tumours
Surgery
Medications
7
Q
WHat tumours cause ectopic secretion of ADH leading to SIADH?
A
Cancers of the stomach, duodenum and pancreas
Lymphomas, sarcomas (begins in bone)
CNS disorders: Encephalitis, meningitis
8
Q
What surgery causes SIADH?
A
ANy surgery can rsult in increased ADH secrertion for up to 5-7 days
9
Q
Why does surgery cause increased ADH?
A
It is likely related to fluid and volume changes following surgery
Following pituitary surgery, ADH is released in an unregulated manner
10
Q
What medications cause SIADH?
A
Hypoglycemic medications (for diabetes mellitus)
Opioids
Antidepressants
Anti-inflammatory
11
Q
What is the key feature of SIADH?
A
Increased kidney water reabsorption to peritubular capillaries
12
Q
What is the mechanism of SIADH?
A
Increased ADH secretion causes increased water channel proteins inserted into the tubular luminal membrane
13
Q
What is the result of SIADH?
A
Increased water reabsorption into ECF —-> Hypoosmolarity in ECF
14
Q
What is normal osmolarity?
A
Match between [Na+] and [H2O]
15
Q
What is hyperosmolarity?
A
More [Na+] than [H2O]
16
Q
What is hypoosmolarity?
A
Less [Na+] than [H2O]
17
Q
What do symptoms of SIADH result from?
A
Hyponatremia (Low blood [Na+])
18
Q
What causes Hyponatremia (SIADH)?
A
-Low [Na+] bc of increased H2O reabsorption from kidney without matching levels of Na+ reabsorption
19
Q
What do the effects of SIADH depend on?
A
Severity and rapidity of onset
-Serum sodium levels decrease rapidly from 140-130 mmol/L
20
Q
SIADH effects: 130-120 mmol/L?
A
Vomiting
Abdominal cramps
Weight gain
21
Q
SIADH effects: below 110 mmol/L?
A
Confusion
lethargy
muscle twitches
convulsions
22
Q
How do symptoms of SIADH normally resolve?
A
With the correction of hyponatremia
23
Q
What is diabetes insipidus/
A
Insufficiency of ADH activity leading to polyuria and polydipsia
24
Q
Polyuria
A
Frequent urination
25
Polydipsia
Frequent drinking
26
What are the two forms of diabetes insipidus?
Neurogenic or Central
Nephrogenic
27
What causes neurogenic or central diabetes insipidus?
Insufficient secretion of ADH from the posterior pituitary
Lesions of the hypothalamus
PP interference with transport/release of ADH
Brain tumours, aneurysms
28
Diabetes Insipidus is a well-recognized complication of what?
Traumatic Brain Injury
29
What are the two types of Nephrogenic DI?
Acquired
Genetic
30
What is Acquired DI?
Related to medication disorders that damage renal tubules
31
What disorders are included in acquired DI?
Pyelonephritis (UTI)
Polycystic kidney disease
32
Polycystic kidney disease
A genetic disorder that causes many fluid-filled cysts to grow in your kidneys
33
What is Genetic DI?
Mutation of gene coding for aquaporin-2 (water channel)
34
What is a rare form of DI?
DI associated with pregnancy
35
How can pregnancy cause diabetes insipidus?
Increase in level of vasopressin-degrading enzyme; Vasopressinase
-Mild, doesn't need treatment
36
What leads to Diabetes Insipidus?
Total inability to alter the concentration of urine caused by insufficient ADH
37
What does insufficient ADH lead to?
Large volumes of dilute urine and increased plasma osmolarity
38
Serum levels associated with DI?
Serum hypernatremia and hyperosmolarity
39
What are the clinical signs of diabetes insipidus?
Polyuria
Nocturia (waking to urinate)
Polydipsia
40
What is the normal urinary output?
1-2 L/day
41
What is someone with DI's urinary output?
As high as 8-12 L/day and can be higher than daily fluid intake
42
What are the manifestations of longstanding DI?
Enlarged bladder capacity and hydronephrosis (swelling on one or both kidneys)
43
What is the onset of neurogenic DI?
Sudden
44
What is the onset of Nephrogenic DI?
Gradual
45
How is diabetes insipidus diagnosed?
Dilute urine
Hyperosmolarity, hypernatremia
Continued diuresis despite high serum osmolarity
46
Diabetes insipidus treatment?
ADH replacement
Oral or IV fluid replacement
Medications that increase the action of available ADH include carbamazepine (Tegretol)
New treatments: Reversing aquaporin-2 dysfunction
47
What are thyroid function disorders generally due to?
Primary dysfunction of the thyroid gland
48
Secondary dysfunction (thyroid disorders) occur because of?
Pituitary or hypothalamic alterations
49
What is Subclinical thyroid disease?
Thyroid disease with no symptoms but abnormal laboratory values
50
What thyroid disorder terms are often used interchangeably but have a subtle difference?
Thyrotoxicosis and Hyperthyroidism
51
Thyrotoxicosis
A condition resulting from any cause of increased hormone levels
52
Hyperthyroidism
Excess secretion of thyroid hormone from thyroid gland
53
What are common diseases that cause primary hyperthyroidism?
Graves disease
Toxic multinodular goiter
54
What are features of thyrotoxicosis caused by?
Metabolic effects of increased serum thyroid hormones
55
How does thyrotoxicosis/hyperthyroidism manifest?
Increased metabolic rate
Increased heat intolerance
Increased tissue sensitivity to SNS stimulation
56
Signs/symptoms of Hypothyroidism?
Periorbital edema (swelling around eyes)
Smaller thyroid
Bradycardia
Constipation
Edema of extremities
57
Signs/syptoms of Hyperthyroidism?
Expothalmos (buldging, protruding eyes)
Enlarged thyroid
tachycardia
diarrhea
Pretibial edema (anterior skin lesions of tibial region)
58
What is the underlying cause of 80% of hyperthyroidism?
Grave's disease
59
Grave's disease is more common in which gender?
Females
60
What is the exact cause of Grave's disease?
The exact cause is unknown
-Likely genetic with environmental aspects
61
What kind of disease is Grave's disease?
Autoimmune
62
What is the autoimmune result of Grave's disease?
Autoantibodies stimulate receptors on the thyroid gland
63
What are the antibodies associated with grave's disease?
Thyroid-stimulating immunoglobulins (TSIs)
64
What do TSIs do?
Override normal regulatory mechanisms
65
What does TSI stimulation cause?
Hyperplasia of gland and increased secretion of TH (especially T3)
66
What 2 manifestions of Grave's disease do TSIs contribute to?
1. Abnormalities from hyperactivity of Sympathetic Nervous System
2. Changes to orbital contents with enlargement of orbital muscles
67
What is the result of Grave's disease/
Exophthalmos
Diplopia (double vision)
Decrease visual acuity
Pretibial myxedema
68
Pretibial myxedema
Subcutaneous swelling of anterior portion of legs
69
What causes pretibial myxedema swelling?
Recruited t cells that stimulate excessive amounts of hyaluronic acid production
70
Hyaluronic acid
Natural substance found in fluids in eyes and joints
71
What is normal nodular thyroid disease?
Thyroid enlarges in response to increased demand for TH, when the condition subsides, the thyroid returns to normal size
72
What is Abnormal nodular thyroid disease?
Irreversible change sin some follicular cells causing the production of excess TH
73
What is a toxic multi-nodular goitre?
Several nodules increase in size and increase TH output causing thyroid gland to get bigger
74
What is Thyrotoxic crisus (thyroid storm)?
Rare/dangerously worsening state of excessive release of TH
75
When can death occur bc of Thyrotoxic crisis?
Within 24 hours without treatment
76
What individuals experience Thyrotoxic crisis?
Those with Grave's disease and subject to infection, pulmonary or CV disorder
77
What can a thyrotoxic crisis occur because of?
Thyroid surgery
78
What is Hypothyroidism?
Results from deficient TH production by the thyroid gland
79
What are the two kinds of Hypothyroidism?
Primary
Central (secondary)
80
What kind of hypothyroidism accounts for most cases?
Primary
81
What is secondary/central hypothyroidism related to?
Pituitary or hypothalamic failure
82
What is Autoimmune thyroiditis?
aka Hashimoto's disease
Chronic lymphocytic thyroiditis
83
What is the most common cause of primary hypothyroidism in Canada?
Autoimmune thyroiditis (Hashimoto's)
84
What does Hashimoto's disease do?
Causes gradual inflammatory destruction of thyroid tissue
85
What causes Autoimmune thyroiditis (Hashimoto's)?
infiltration of autoreactive T cells, NK cells, and induction of apoptosis
86
Who is affected by Congenital hypothyroidism?
Infants with thyroid tissue absent or with hereditary defects in TH synthesis
87
What is TH essential for?
Embryonic growth, particularly brain tissue
88
What is the fetus dependent upon for the first 20 weeks of gestation?
Maternal T4
89
What can a lack of maternal T4 cause?
Cognitive defects
90
What are the symptoms of congenital hypothyroidism?
High birth weight
Hypothermia
neonatal jaundice
91
What kind of examination can provide T4 and TSH levels?
Umbilical cord blood exam
92
Normal growth and intellectual function can occur with the treatment of what? (Congenital hypothyroidism)
Levothyroxine
93
When must treatment of levothyroxine be used?
Before child is 4 months old
94
Without screening, hypothyroidism may be difficult to determine before what age?
4 months
95
What are the symptoms of congenital hypothyroidism before 4 months?
difficulty eating
horse cry
protruding tongue
excessive sleeping
96
What is the most common pediatric disease?
Type 1 Diabetes mellitus
97
What percent of Canadians have Type 1 diabetes?
10%
98
What is Type 1 diabetes linked to?
Strong genetic link
Environmental factors (medications, viruses)
99
What is type 1 diabetes mellitus?
Slow progressing autoimmune T-cell-mediated disease that destroys pancreatic cells
100
How do gene-environment interactions contribute to Type 1 Diabetes Mellitus?
They lead to the formation of autoantigens expressed on pancreatic beta cells.
101
What happens to autoantigens in Type 1 Diabetes Mellitus?
Autoantigens detach and circulate in the bloodstream and lymphatics.
102
What cells activate in Type 1 diabetes mellitus because of autoantigens?
Macrophages
T-cytotoxic cells
103
What results from activating T-cytotoxic cells and macrophages in Type 1 Diabetes Mellitus?
The production of autoantibodies occurs.
104
What is the final outcome of the autoimmune response in Type 1 Diabetes Mellitus?
The destruction of pancreatic beta cells, leading to reduced insulin secretion.
105
How many beta cells must be destroyed for insulin to decline enough, causing hyperglycemia to develop in Type 1 Diabetes Mellitus?
80-90% of beta cells must be destroyed
106
How does type 1 diabetes manifest?
Insulin deficiency + hyperglycemia
-Glucose builds up in blood and urine
-Glucose concentration in urine exceeds renal threshhold
107
What occurs when glucose build up in blood during Type 1 diabetes?
diuresis (excessive urination)
Dramatic increase in thirst
108
What condition can develop because of Type 1 diabetes lack of insulin?
Diabetic ketoacidosis
-Can be life-threatening
109
What causes diabetic ketoacidosis?
Proteins and fat become utilized leading to high levels of circulating ketones due to lack of insulin
110
What kind of diabetes accounts for 90% of all diabetes in Canada?
Type 2 Diabetes Mellitus
111
What are risk factors associated with Type 2 diabetes?
Age
Obesity
Hypertension
Physical activity
Family history
112
What is Type 2 diabetes occurrence linked to?
More than 60 genes which code for beta cell mass and functionality
113
What two mechanisms are a result of Type 2 diabetes?
Insulin resistance
decreased insulin secretion by beta cells
114
What is Type 2 diabetes?
A sub-optimal response of insulin-sensitive tissue (especially liver, muscle, and adipose tissue), leading to a condition of insulin resistance due to cell dysfunction of insulin receptors.
115
What is one mechanism involved in the development of insulin resistance in Type 2 Diabetes Mellitus related to obesity?
Obesity results in increased serum levels of leptin and decreased levels of adiponectin, which are associated with inflammation and insulin sensitivity.
116
How do elevated levels of serum free fatty acids contribute to insulin resistance in Type 2 Diabetes Mellitus?
They cause intracellular deposits of triglycerides, which decrease tissue response to insulin, leading to insulin resistance.
117
What is obesity linked to in Type 2 Diabetes Mellitus?
Obesity is linked to hyperinsulinemia and decreased insulin receptor density.
118
What is the result of the mechanisms involved in insulin resistance in Type 2 Diabetes Mellitus?
Hyperinsulinemia
119
What is the effect of hyperinsulinemia on beta cells in Type 2 Diabetes Mellitus?
Beta-cell "exhaustion," which involves a decrease in beta-cell mass and dysfunction of normal beta-cell function.
120
What is Cushing's syndrome?
Chronic exposure to excess cortisol
121
What is cushing's disease of result of?
Excess secretion of ACTH by anterior pituitary or an ectopic-secreting nonpituitatry tumour
122
What two observations apply with hypercortisolism?
1. Normal diurnal secretion patterns of
ACTH and cortisol are lost
2. There is no increased ACTH and cortisol
secretion in response to stress
123
WHat is the result of the two observations that apply to hypercortisolism?
Excess ACTH secretion but a loss of negative-feedback controls on ACTH secretion
Hypercortisolism symptoms develop
124
How does Cushing's syndrome manifest?
Weight gain
-Face, trunk, buffalo hump
125
What causes the weight gain associated with Cushing's?
Cortisol increases cravings to increase fats and carbs available for fuel
126
What does cortisol increase the release of?
Glucose
127
What intolerance can develop during Cushing's?
Glucose intolrance because of cortisol-induced insulin resistance
128
What bone condition is a result of Cushing's?
Osteoporosis
-Bone components reabsorbed
129
How does Cushing's cause muscle wasting?
Cortisol is use to break down proteins for a.a release
130
How are the vertebrae affected by cushings?
Veretebral compression fractures
Kyphosis (outward curve of spine 'humpback')
Reduced height
131
How is the skin affected by Cushing's?
Weakened integumentary tissue
-stretched skin
132
What is supressed because of Cushing's?
Immune system
