Thyroid path & Chemical pathology Flashcards
1
Q
What is Thyrotoxicosis ?
A
Thyrotoxicosis is the hypermetabolic state caused by increased levels of circulating thyroid hormones most commonly due to hyperthyroidism.
2
Q
True or False? Grave’s disease is as a result of Hypothyroidism.
A
FALSE!! It is as a result of Hyperthyroidism
3
Q
What are diseases that are as a result of Hypothyroidism?
A
- Hashimoto’s thyroiditis
- Iatrogenic : surgery , radiation, drugs
- Dyshormonogenetic goitre( congenital biosynthetic defect)
4
Q
What are the most common causes of Hyperthyroidism as a result of over functioning of the Thyroid gland?
A
- Graves disease( diffuse toxic hyperplasia)
- Hyper-functioning (“toxic”) multinodular goiter.
- Hyperfunctional (“toxic”) adenoma of the thyroid
5
Q
What is the main circulating antibody produced in Grave’s disease?
A
IgG
G for Graves duuhhh
6
Q
True or False? Grave’s disease is considered a Type I hypersensitivity reaction.
A
FALSE!! It is a Type II sensitivity reaction.
7
Q
What is the main gene associated with Grave’s disease?
A
HLA- DR3 and HLA-B8.
8
Q
What are the autoantibodies that are produced in Grave’s disease?
A
- Thyroid-stimulating immunoglobulin.
- Thyroid-Growth stimulating immunoglobulin.
- TSH- binding inhibitor immunoglobulin
9
Q
Fill in the blanks. “ Multinodular goitre (MNG) is due to _____. “
A
Impaired synthesis of thyroid hormone.
10
Q
Multinodulular goitre can arise as a result of a deficiency of what nutrient?
A
Dietary iodine
11
Q
Which autoantibody in Grave’s disease is an IgG anti-body that binds to the TSH receptor and mimics the action of TSH?
A
Thyroid-stimulating immunoglobulin (TSI).
12
Q
Which autoantibody in Grave’s disease antibodies have been implicated in the proliferation of thyroid follicular epithelium?
A
Thyroid Growth stimulating immunoglobulin .
13
Q
Which autoantibody in Grave’s disease is anti-TSH receptor antibodies prevent TSH from binding to its receptor on thyroid epithelial cells and in so doing may inhibit thyroid cell function ?
A
TSH-binding inhibitor immunoglobulins.
14
Q
What happens to the TSH levels if there is an impairment of Thyroid hormone such as in Goitre?
A
Increase in serum TSH
15
Q
True or False? In goitre, The degree of thyroid enlargement is proportional to the level and duration of thyroid hormone deficiency.
A
TRUE!!
16
Q
What are the different types of Multinodular goitre?
A
Sporadic or Endemic
17
Q
When does Endemic goitre occur?
A
Endemic is used when goiters are present in more than 10% of the population in a given region.
18
Q
What are the clinical features of Multinodular goitre’s?
A
Multiple nodules
Cysts
Haemorrhage
Fibrosis
Dystrophic calcification
Airway obstruction, dysphagia
Superior Vena Cava syndrome
Plummer syndrome
19
Q
True or False? Thyroid adenomas are malignant.
A
FALSE!! They are benign
20
Q
Which types of nodules are likely to be neoplastic?
A
- Solitary nodules
- Nodules in very young and very old persons.
- Nodules in males
- Nodules in males»>nodules in females.
*Nodules that take up radioactive iodine in imaging studies (hot nodules) are more likely to be benign.
21
Q
True or False? Cold nodules are likely to be benign while 10% of hot nodules are likely to become malignant.
A
FALSE!! 10% of cold nodules eventually prove to be malignant while Hot nodules are benign.
22
Q
What are examples of Hot nodules?
A
Toxic adenoma- Produces T3 & T4 independent of TSH.
23
Q
Which thyroid carcinoma is NOT derived from Thyroid follicular epithelium?
A
Medullary carcinoma
24
Q
What are the types of Thyroid carcinoma?
A
- Papillary carcinoma (accounting for more than 85% of cases)
- Follicular carcinoma (5% to 15% of cases)
- Anaplastic (undifferentiated) carcinoma (<5% of cases)
- Medullary carcinoma (5% of cases)
25
Which gene mutation is associated with Follicular carcinoma of the Thyroid gland?
RAS or PI3K/AKT signaling pathway
26
Fill in the blanks. " Follicular carcinoma of Thyroid gland is diagnosed only by _______."
* Invasion through capsule
* Vascular invasion
27
What gene mutations are associated with Papillary carcinoma?
Activation of the MAP kinase pathway is a feature of most papillary carcinomas.
*RET on chromosome 10q ---> leading to fusion gene called ret/PTC.
28
Which type of Thyroid carcinoma presents with an Optically Clea nuclei ( Orphan Annie eye)?
Papillary carcinoma
29
What are the histological findings in Papillary carcinoma of the Thyroid gland?
* Papillae ( duh)
* Can be composed of follicles
* Overlapping nuclei with grooves
* Optically clear nuclei ( Orphan Annie eye)
* Nuclei pseudo-inclusions
* Psammoma bodies in stoma of papillae
30
Where do Medullary carcinoma arise from?
Parafollicular C cells
31
Fill in the blanks. " 80% of Medullay carcinoma can be _____ while 20% can be _____."
80%- Sporadic ( 5th & 6th decade)
20%- Familial ( Young adults & kids )
32
What gene mutation is associated with Medullary carcinoma of the Thyroid gland?
RET
33
In what type of diseases can Familial Medullary carcinoma occur in also?
Multiple endocrine neoplasia type 2 (MEN-2) or Familial medullary thyroid carcinoma (FMTC)
34
Which gene mutation is associated with Anaplastic carcinoma?
TP53
35
Which carcinoma of the Thyroid gland can arise by progression of a well-differentiated papillary or follicular carcinoma?
Anaplastic carcinoma
36
The spread of Papillary carcinoma of the Thyroid gland occurs through what lymph nodes?
They spread mainly via lymphatics to cervical lymph nodes
37
Which type of Thyroid carcinoma is associate with Hürthle cells?
Follicular carcinoma
38
What substance is secreted by Medullary thyroid carcinomas?
Calcitonin ( because its occurs from the Parafollicular , C cells)
* can be used for diagnosis
39
Which carcinoma of the Thyroid gland can present with Amyloid deposits?
Medullary carcinoma
40
What are symptoms of Cretinism seen in Hypothyroidism?
* Impaired development of the skeletal system and central nervous system.
* Severe mental retardation.
* Short stature
* Coarse facial feature
* A protruding tongue,
* Umbilical hernia.
41
What are the symptoms of Myxedema seen in Hypothyroidism?
* Increased generalized fatigue
* Increased apathy,
* Increased mental slug- gishness, which may mimic depression
* Constipation
* Decreased sweating
*Non- pitting edema,
* Broadening and coarsening of facial features
* Enlargement of the tongue
* Deepening of the voice.
42
True or False? Serum T4 is decreased in Hypothyroidism.
TRUE!!
43
What are examples of Autoimmune Thyroiditis?
Hashimoto's disease
Lymphocytic thyroiditis
Subacute Thyroiditis
44
Which substance is an intracellular second messenger for secretion of some hormones and neurotransmitters?
Calcium
45
What are the three forms that Calcium are present in the blood plasma?
* Ionized Ca2+
* Protein Bound
* Complexed ( citrates, phosphates)
46
What is the physiologically active form of Calcium in the body?
Ionized Ca2+
47
Calcium is 80% bounded to what Protein in the blood plasma?
Albumin
48
What is the total calcium reference range?
2.25 – 2.75 mmol/L.
49
What is the ionized calcium reference range?
1.1 – 1.4 mmol/L.
50
What are the names of the Calcium regulating hormones?
* Parathyroid hormone (PTH)
* Calcitriol (1:25-dihydroxycholecalciferol)
* Calcitonin (minor role).
51
Fill in the blanks ." Calcium regulating hormones also ____."
Control the inorganic phosphate concentration of the ECF.
52
Which structure produces Parathyroid hormone?
Chief cells
53
True or False? Parathyroid hormone is a steroid.
FALSE!! It is a polypeptide comprising 84 amino acids.
54
What is the half life of Parathyroid hormone in the blood?
3-4 mins
55
Where does the biological activity reside in PTH?
N-terminal 1-34 amino acid sequence.
56
What is the principal acute regulator of Plasma Calcium?
Parathyroid hormone
57
True or False? Plasma PTH is lowest at about 1/2 am and highest at about 9 am.
FALSE!! It is lowest at 9 am and highest in the early morning 1 or 2 am.
58
What is the mechanism of action for parathyroid hormone in regards to calcium levels?
The active hormone is secreted in response to a fall in plasma [Ca2+], and its actions are directed to increase plasma [Ca2+].
59
What is the name of the receptor that Parathyroid hormone acts on ?
The parathyroid hormone 1 receptor & parathyroid hormone 2 receptors
60
Where are parathyroid hormone 1 receptors located?
High levels in bone & kidney
61
Where are parathyroid hormone 2 receptors located?
High levels in the central nervous system, pancreas, testis, and placenta
62
Fill in the blanks. "Binding of PTH to its receptor activates 2 signaling pathways:______ & _______"
* Increased cyclic AMP
* Increased phospholipase C
63
True or False? An increase in plasma [Ca2+] suppresses PTH secretion.
TRUE!!
64
What happens when PTH acts on the kidneys?
There is a net effect of lowering glomerular filtration rate (GFR), increasing the reabsorption of calcium and magnesium, and decreasing the reabsorption of phosphate and bicarbonate (increase excretion).
65
What substance is produced when PTH acts on the kidneys?
It stimulates the production of biological active form of Vitamin D- 1,25(OH) 2D.
66
How does PTH act on the bones?
It increases the degradation of bones ( which INCREASES the release of calcium)
67
True or False? PTH will stimulate Osteoclasts but NOT Osteoblast activity.
FALSE!! It will stimulate both Osteoclast & Osteoblast activity.
68
How does PTH stimulate Osteoclasts?
PTH stimulates bone stem cells to develop into osteoclasts
69
When PTH stimulates Osteoblast activity what other substance is increased?
ALP & a calcium-binding protein osteocalcin
70
Fill in the blanks. " Most vitamin D3 (Cholecalciferol) is synthesized by the action of ________ on 7-hydrocholesterol precursor in the skin."
Ultraviolet light rays
71
What is the name of the enzyme that catalyzes the hydroxylation of cholecalciferol with the formation of 25-hydroxycholecalciferol (25-HCC, calcidiol)?
25-Hydoxylase
72
True or False? Vitamin D is actually a hormone than a vitamin.
TRUE!!
73
Which form of Vitamin D is measured in the blood?
Calcidiol ( 25- OH or Hydroxy vitamin D)
74
What is the plasma half life of Calcidiol?
15-25 days
75
Where does Calcidiol undergo hydroxylation to form Calcitriol (1:25-DHCC) - active vit D?
In the kidney
76
What is the name of the enzyme which aids in the formation of Calcitriol from Calcidiol ?
1-α hydroxylase
77
What is the active form of Vitamin D3?
Calcitriol (1,25 dihydroxy Vitamin D)
78
What is the inactive form of Vitamin D3?
Calcitroic acid (24,25 - dihydroxy vitamin D)
79
Where is 1α-hydroxylase enzyme located ?
In the proximal convoluted tubules of the nephrons.
80
The enzyme 1α-hydroxylase is inhibited by what substances?
1:25-DHCC (Calcitriol) and by hyperphosphataemia (high phosphate)
81
The enzyme 1α-hydroxylase is stimulated by what substances?
PTH and hypophosphataemia (low phosphate)
82
What is the name of the enzyme that converts Calcidiol ( 25, hydroxycholecalciferol or 25 HCC) to Calcitroic acid ( 24,25 dihydroxycholecalciferol) ?
24-hydroxylase
83
What are the main actions of Calcitriol?
* Promotes intestinal reabsorption of calcium .
* Promotes bone mobilization.
84
What is the name of the calcium- binding protein that promotes the absorption of calcium and phosphate from the gut lumen to the plasma compartment?
Calbindin-D
85
Calcitonin is produced by what cells?
Parafollicular or C cells
86
What is the main target cell for Calcitonin?
Osteoclasts
87
True or False? Calcitonin Increases osteoclast activity but DECREASES osteoblast activity.
FALSE!! Calcitonin Inhibits Osteoclasts activity but Increases Osteoblastic activity .
88
During what conditions are Calcitonin levels increased?
Pregnancy & Lactation
89
What are the actions of Calcitonin?
* It lowers Calcium
* It inhibits Calcium absorption by intestines
* Inhibits Calcium reabsorption in the kidney.
* Inhibits Osteoclasts
* Promotes deposition of Calcium into bones
90
What are the common cause of Hypercalcemia?
* Malignant disease, e.g. some lung cancers
* Hyperparathyroidism
* Vitamin D toxicity (excessive intake
91
What are the uncommon causes of Hypercalcemia?
* Renal failure
* Sarcoidosis
* Multiple myeloma
92
What is the most common single presenting complaint from a patient with Primary Hyperparathyroidism?
Renal stones
93
What is Primary Hyperparathyroidsim characterised by?
Hypercalcemia
Hypercalcuria
Hypophosphatemia
Hyperphosphaturia.
94
What is Primary Hyperparathyroidism?
There is the autonomous production of PTH which occurs from a single, parathyroid adenoma (tumour), diffuse hyperplasia (all four glands) or, rarely, parathyroid carcinoma may be responsible.
95
What are the causes of Secondary Hyperparathyroidism ?
* Kidney failure during dialysis
* Celiac disease
*Crohn's disease
*Severe vit D deficiency
*Stomach or Intestinal Obesity surgery.
96
In what type of patients is secondary hyperparathyroidism seen?
* It occurs in patients with chronic renal failure or in disorders where there is malabsorption of fat soluble vitamin D.
* Osteromalcacia &rickets
97
What happens to the Calcitriol production when the phosphate levels are increased?
An increase in phosphate level suppresses Calcitriol production .
98
What are the factors implicated in Hypercalcemia of malignancy?
* Tumour necrosis factor,
* Interleukin -1
* Prostaglandins.
99
True or False? The very high plasma total calcium usually observed in patients with multiple myeloma reflects increased binding of calcium by paraprotein.
TRUE!!
100
Fill in the blanks. " In Hypercalcemia of malignancy , The malignant plasma cells secrete immunoglobulin of a single class only called a ________."
Paraprotein or monoclonal
101
What is Milk alkali syndrome?
Decrease renal excretion of calcium. Ingestion of alkali decreases renal excretion of calcium
102
Which drug can cause Hypercalcemia?
Thiazides diuretics
103
True or False? Vitamin D deficiency can cause Hypocalcemia.
TRUE!!
104
Which drug can induce enzymes that catabolise vitamin D?
Phenytoin
105
What are the causes of Hypoparathyroidism?
Thyroid surgery
Parathyroid surgery
Autoimmune
Infiltrative
Familial
Idiopathic
106
What is Pseudohypoparathyroidism?
Pseudohypoparathyroidism is a genetic disorder associated primarily with resistance to the parathyroid hormone (body fail to respond to PTH).
107
What are the clinical findings in Pseudohypothyroidism ?
Low serum calcium
High Phosphate
High PTH
108
What happens in Type I pseudohypoparathyroidism ?
Activation of adenyl cyclase is defective and cyclic AMP is not formed in response to the binding of PTH to its receptor.
109
What happens in Type II Pseudohypoparathyroidism?
Cyclic AMP is formed, but the response to it is blocked (defective G proteins).
110
How can one differentiate between Type I and Type II Pseudohypoparathyroidism?
By measuring the urinary cyclic AMP levels
111
What is the function of the hypothalamic-pituitary axis ?
To regulate hormone function.
112
Fill in the blanks." Release of TSH from the pituitary gland is stimulated by _____________ from the hypothalamus."
Thyrotropin releasing hormone (TRH)
113
What is the Hypothalamic- Pituitary axis?
The hypothalamic-pituitary axis is a classical negative feedback regulatory mechanism in which secretion of thyroid stimulating hormone (TSH) is modulated by thyroid hormones (FT3 & FT4).
114
Where in the body is T4 (Thyroxine) converted to T3 ( Triiofothyronine)?
In the kidneys, liver, brain and Skeletal muscle
115
What is the name of the enzyme that converts T4 to T3?
Iodothyronine Deiodinase
116
What is an inactive byproduct of Deiodination?
rT3 - Reverse T3
117
What is the normal amount of T3 produced on a daily basis?
6 mcg/day
118
What is the normal amount of T4 produced on a daily basis?
100 mcg/day
119
What is the name of the hormone that stimulates Thyroid gland to release thyroid hormone?
Thyroid -stimulating hormone TSH ( Thyrotropin )
120
What substances act at the hypothalamic level by inhibiting mRNA for TRH synthesis?
T3 &T4
121
What is the name of the transporter by which iodide enters the follicular lumen from the cytoplasm?
Pendrin
122
What is the name of the enzyme that aids in the oxidation of iodide to IODINE?
Thyroid peroxidase
123
Where does oxidation of Iodide to Iodine occur?
In the colloid
124
Fill in the blanks. "Iodine (I0) is very reactive and iodinates the thyroglobulin at ________ in its protein chain. "
Tyrosyl residues
125
What are the substances formed at the end of Conjugation?
* Mono-iodotyrosine (MIT)
* Di-iodotyrosine (DIT)
126
What is the name of the process in T3& T4 synthesis in which adjacent tyrosyl residues are paired together?
Conjugation
127
How is the production of T3 & T4 formed?
By the coupling iodotyrosyl residues in the thyroglobulin molecule.
( MIT + DIT = T3)
(DIT +DIT = T4)
128
What are the functions of the Thyroid gland?
1. Role in growth
2. Role in CNS development
3.Stimulates heart rate
4. Stimulates heart contraction .
5. Stimulates synthesis of proteins and carbohydrates
6. Degrade cholesterol & Triglycerides
7. Enhances beta- adrenergic receptors to catecholamines
8.It increases vitamin requirements
9. Increase gluconeogenesis & glycogenesis
10. Increases glucose intestinal absorption
129
Thyroid releasing hormone is produced by ?
Hypothalamus
130
True or False? Thyroid releasing hormone is down-regulated by T4.
FALSE!! It is down-regulated by T3
131
Fill in the blanks. " Thyroid stimulating hormone is secreted by _______."
Thyrotrophs of the anterior pituitary.
132
What is the major external regulator of the Thyroid gland?
Thyroid stimulating hormone (TSH)
133
Where is the TSH receptor located?
On the BASAL surface of the thyroid follicular cell.
134
What happens when there is an INCREASE in plasma TSH?
* Release of formed T3 and T4
* Increased rate of iodide uptake
* Increased rate of synthesis
* Increased size and number of follicles.
135
What happens to the TSH levels in Primary HYPOTHYROIDISM ?
They are HIGH !!
136
What is the most sensitive screen test for hyperthyroidism and primary hypothyroidism ?
Testing the TSH levels
137
True or False? In Secondary Hypothyroidism the TSH levels is HIGH while in Tertiary Hypothyroidism the TSH levels are Normal.
FALSE!! It is appropriately NORMAL or LOW in secomdary & tertiary hypothyroidism
138
Why is the TSH levels high in Primary hypOthyroidism?
This occurs because of a loss of feedback inhibition of thyrotropin-releasing hormone (TRH) and TSH production by the hypothalamus and pituitary, respectively
139
True or False? The TSH levels are also INCREASED in individuals with hypO thyroidism caused by primary hypothalamic or pituitary disease.
FALSE!! The TSH concentration is NOT increased in individuals with hypo- thyroidism caused by primary hypothalamic or pituitary disease.
140
What is the name of the substance to which thyroid hormones are bound to and transported in the blood?
* Thyroxine-binding globulin (TBG) binds about 70% of plasma T4 and 80% of plasma T3.
*Thyroxine-binding pre-albumin and albumin .
141
What percentage of T4 & T3 are free ( unbound to protein)
T4 - 0.05%
T3 - 0.2%
142
What is the normal concentration of Total T4?
60 – 150 nmol/L
143
What is the normal concentration of T3?
1.0 – 2.9 nmol/L
144
What drugs can cause a DECREASE in Thyroxine - binding globulins ?
* Anabolic Steroids ( Androgens)
* Glucocorticoids
145
What drugs can cause an INCREASE in Thyroxine - binding globulins ?
* Oral contraceptives ( oestrogens)
* Heroin or Methadone abuse
* Clofibrate or 5- Fluorouacil ( Adrucil)
146
Which classification of Thyroid Function tests deals with testing the primary function of the Thyroid Gland?
Group I
147
Fill in the blanks." Group III Thyroid function test measures _____."
The Metabolic effects of the Thyroid hormone.
148
Which classification of Thyroid Function tests deals with the Immunological tests for auto-immune diseases?
Group IV
149
Which classification of Thyroid Function tests deals with the measurement of blood levels of thyroid hormones?
Group II
150
What are the clinical aspects of Group IV Thyroid function tests?
Agar gel diffusion test
Complement Fixation Test
151
Which group of thyroid function tests deals with:
- Radio-iodine uptake
-T3 - suppression test
-TSH - stimulation test
- TRH- stimulation test?
Group I
152
Which group of thyroid function tests deals with:
- Basal Metalic rate
- Serum cholesterol level
- Serum creatine
- Serum uric acid
- Serum creatine kinase level?
Group III
153
What are the clinical aspects Group II Thyroid function tests?
- Total T3 & T4
- Free T3 &T4 levels
- Circulating TSH levels
- Plasma Tyrosine level
154
What is the normal of TSH?
0.4 – 4.0 mU/L
155
What is the concentration of Free T3 (triiodothyronine)?
1.5 – 4.1 pg/mL
156
What is the concentration Free T4 (thyroxine)?
0.8 – 1.9 pmol/L
157
What are nutrients that can be tested for during Thyroid tests?
Vitamin D
Vitamin B12
Iodine
Magnesium
Iron
Zinc
158
What is the autoantibody thyroid test that can be used for suspected Hypothyroidism/ Hashimotos's?
Thyroid Peroxidase Antibodies
(TPO)
159
What is the autoantibody thyroid test that can be used for suspected Hyperthyroidism/ Grave's?
Thyroid Stimulating Immunoglobin (TSI)
160
Fill in the blanks. " Primary thyroid disease is an abnormality of ________."
Thyroid Gland
161
True or False? Secondary Thyroid disease is abnormality in hypothalamus while Tertiary Thyroid diseases an abnormality in pituitary gland.
FALSE!! Second thyroid disease is really an abnormality in PITUITARY GLAND.
Tertiary thyroid disease is abnormality in HYPOTHALAMUS
162
Fill in the blanks. "In Secondary Thyroid diseases, an abnormal amount of __________ is produced ."
Thyroid stimulating hormone(TSH)
163
Fill in the blanks. "In Tertiary Thyroid diseases, an abnormal amount of __________ is produced ."
Thyrotropin-releasing hormone (TRH )
164
During Hypothyroidism , what happens to the Plasma Free T4 levels?
It is DECREASED
165
During Hypothyroidism, what happens to the Plasma Free T3 levels.
It remains NORMAL
166
During Hypothyroidism, what happens to the TSH levels?
It is INCREASED
167
What are the conditions which can cause an Increase in Radio-active uptake?
* Grave's disease
* Toxic multi- nodular goitre
* Toxic adenoma
* hCG secreting tumours - hyadatidiform mole
- choriocarcinoma
* TSH mediated thyrotoxicosis
- pituitary tumour
- pituitary resistance to thyroid hormone
* Iodine deficiency
168
Fill in the blanks. " Low uptake or radioactive iodine suggests ______, while high uptake of radioactive iodine suggests _________."
Low uptake suggests THYROIDITIS , high uptake suggests GRAVES DISEASE
169
What are examples of Primary Hyperthyroidism?
* Graves disease
* Autonomous toxic adenoma
* Multinodular toxic goitre
*Iodine Overload , Procor
170
What are examples of Secondary hyperthyroidism ?
*TSH -producing pituitary adenoma
* Thyroid hormone resistance
* Gestational thyrotoxicosis
171
What happens to the cholesterol level in Grave's disease?
Decreased serum cholesterol
172
What is the most common anti-thyroid antibody that is present in Hashimoto's disease?
* Anti-thyroid peroxidase (anti-microsomal antibodies)
*Anti-thyroglobulin antibodies
173
What are the anti-thyroid antibodies present in Grave's disease?
* Anti-thyroid peroxidase (anti-microsomal antibodies)
*Thyroid stimulating immunoglobulins (thyroid receptor antibodies)
* Anti-thyroglobulin antibodies
174
True or False? Subacute thyroiditis normally occurs after a viral infection of the lower respiratory tract.
FALSE!! Subacute thyroiditis normally occurs after a viral infection of the UPPER respiratory tract.
175
True or False? Subacute thyroiditis is diagnosed based on a very low radioiodine I-123 uptake.
TRUE !!!
176
Fill in the blanks. " Primary Hyperthyroidism is caused by _______."
Thyroid destruction
177
Fill in the blanks. " Secondary Hyperthyroidism is caused by _______."
*A deficiency of Thyroid Stimulating hormone.
* Pituitary or hypothalamic neoplasms.
* Congenital hypopituitarism
* Pituitary necrosis (Sheehan's syndrome)
178
What is the treatment of Hashimoto's disease ?
Levothyroxine
179
What is the Pathogenesis of Hashimoto's thyroiditis
( Chronic lymphocytic thyroiditis) ?
Hashimoto's thyroiditis is an autoimmune disease
in which the immune system reacts against a variety of Thyroid agents.
180
What is the laboratory test used to confirm the diagnosis Hashimoto's thyroiditis?
TSH, T4, and anti-thyroid autoantibodies.
181
What are the laboratory values for Hashimoto's thyroiditis?
High TSH
Low T4
Anti-TPO Ab
Anti-TBG Ab
182
What type of Hypersensitivity is seen is Hashimoto's disease?
Type IV hypersensitivity (cell mediated)
Type II hypersensitive (antibody mediated)
183
Fill in the blanks. " Secondary Hypothyroidism involves _________."
Decreased activity of the thyroid caused by failure of the pituitary gland.
184
What happens to the TSH levels in Secondary Hypothyroidism ?
It is "inappropriately normal" due to the fact that TSH secreted by the pituitary may not be as biologically active, but it is picked up by the assay.
* results are normally generally low
185
What laboratory findings associated with Secondary Hypothyroidism ?
Free T4 (low)
Free T3 (low)
Serum TSH -- Results are generally low in secondary hypothyroidism because the pituitary is damaged. However, normal values may be seen.
186
Which additional laboratory tests can be used to help determine the diagnosis of Secondary Hypothyroidism?
* Increased total cholesterol levels
* Increased liver enzyme (AST)
* Low serum sodium
* Low blood glucose
* Elevated creatine kinase (CK)
187
Which drugs can cause Hypothyroidism?
Dopamine ( secondary /Tertiary)
Lithium
Amiodarone
Interferon
188
What is the inner layer of the Adrenal gland called?
Adrenal medulla
189
What is the outer layer of the Adrenal gland called?
Adrenal cortex
190
What are the main substances secreted by the Adrenal medulla?
Catecholamines - Epinephrine & Norepinephrine
191
What substances are secreted by the Adrenal cortex?
* Glucocorticoid - cortisol.
* Mineralocorticoid - Aldosterone.
192
What are the layers of the Adrenal cortex?
* Zona glomerulosa
* Zona fasciculata
* Zona reticularis
193
Which layer of the Adrenal cortex secretes androgens- androstenedione, dehyroepiandrosterone (DHEA), estrogen, testosterone.
Zona Reticularis
- think rectum - then think male reproductive organ near rectum then think male hormones.
194
Which layer of the adrenal cortex secretes mineralocorticoids- aldosterone ?
Zona glomerulosa
- think glomerulus then think kidney then think water then think aldosterone
195
Which layer of the adrenal cortex secretes glucocorticoids- cortisol, corticosterone?
Zona fasiculata
196
What is Cushing's syndrome?
Cushing's syndrome refers to excess cortisol of any etiology.
197
What is the most common cause of Adrenal Cushing's syndrome ?
Cortisol-secreting adenoma in the cortex of the adrenal gland
198
In Cushing's syndrome , what happens to the ACTH levels?
They are LOW - This is because the tumour will be providing large amounts of cortisol and therefore large amounts of negative feedback on the pituitary.
199
What are the clinical features of Cushing's syndrome?
Truncal Obesity
Moon facies
Buffalo hump
Thinning of skin
Hirsutism (excess hair around mouth and chin )
Hemorrhagic purple-red striae of skin
Glucose- Intolerance
200
What are the different types of Cushing Syndrome?
* ACTH - dependent ( Example - Pituitary
Cushing syndrome and Ectopic (paraneoplastic) Cushing syndrome.)
* ACTH - independent - ( Example - Adrenal adenoma or carcinoma)
* Iatrogenic Cushing syndrome
201
True or False? Pituitary
Cushing syndrome is the ONL ACTH-secreting tumour that is termed Cushing disease.
TRUE!!
202
Where is the most common location for an Ectopic (paraneoplastic) Cushing syndrome?
Lung ( small cell carcinoma of the lung which can also secret ACTH)
203
What is the name of the test that is primarily used to screen for excess cortisol production (Cushing's syndrome) and are useful in detecting dysregulated cortisol hypersecretion?
Dexamethasone suppression tests (DSTs)
204
What other examples of tumours can give rise to Ectopic (paraneoplastic) Cushing's syndrome?
Carcinoids
Medullary cancer of the Thyroid
PanNETS
205
Which drugs can give a false positive of a High dose Dexamethasone suppression tests (DSTs)?
Phenytoin & Rifampicin
206
During the high dose Dexamethasone suppression tests (DSTs), If the ACTH levels are LOW and the cortisol levels is not suppressed it is indicative of what type of Cushing's syndrome?
Adrenal Cushing syndrome
207
During the high dose Dexamethasone suppression tests (DSTs), If the ACTH levels are HIGH and there is Lack of suppression it is indicative of what type of Cushing's syndrome?
Ectopic Cushing syndrome
208
True or False? A serum cortisol concentration < 50 nmol/L (at 0900h) confirms the diagnosis of Addison’s disease).
TRUE!!
209
What is the name of the test given that assess the functioning of the adrenal glands stress response by measuring the adrenal response to adrenocorticotropic hormone (ACTH)?
ACTH stimulation test (also called the Synacthen test)
210
What is the function of Aldosterone?
Promotes sodium retention and potassium elimination by the kidney.
211
What is Conn'syndrome?
This refers to the excess production of the hormone aldosterone from the adrenal glands, resulting in low renin levels.
212
What are the laboratory findings in Conn's syndrome?
High Na
High Chloride
Low Potassium
213
How is the diagnosis of a Pheochromocytoma achieved?
Measuring catecholamines and metanephrines in plasma (blood) or through a 24-hour urine collection.
214
What are the symptoms of a pheochromocytoma?
Paroxysmal attacks
Hypertension
Headaches
Diaphoresis ( Sweating)
Palpitations
215
The presence of what substances can confirm the diagnosis of a pheochromocytoma?
Vanilllyl Mandelic Acid
Homo Vanillyc acid
- Breakdown products of catecholamines
216
What is the treatment for a Pheochromocytoma?
Alpha- blockers ( Phenoxybenzamine)
Surgical removal of tumour
217
What is the common location for a Pheochromocytoma?
Medulla of the adrenal glands
218
What is a pheochromocytoma?
Pheochromocytoma (PCC) is a neuroendocrine tumour of the medulla of the adrenal glands that secretes high amounts of catecholamines, mostly norepinephrine, plus epinephrine to a lesser extent.
219
Metanephrine and Normetanephrie are metabolites created by the action of which enzyme?
Catechol-O-methyl transferase
220
Which drug can you give you false positive when testing for the diagnosis of a pheochromocytoma using Metanephrine &. Nor-metanephrine?
Acetaminophen
221
What is the name of the enzyme that breaks down Metanephrine to Vanillymandelic Acid
(VMA)?
Monoamine Oxidase ( MAO)
222
