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Clinical Chemistry 1 > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

What body processes does the endocrine system control?

A
  1. Growth and development.
  2. Metabolism.
  3. Reproduction.
  4. Homeostasis.
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2
Q

Name some of the organs and tissues of the endocrine system identified in class.

A
  1. Pituitary Glands.
  2. Thyroid Gland.
  3. Parathyroid Glands.
  4. Adrenal Glands.
  5. Pancreas.
  6. Ovaries and Testes.
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3
Q

What is the endocrine system?

A

A communication system including glands and hormones.

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4
Q

What are hormones?

A

Chemical substances used for intracellular and extracellular communication.

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5
Q

How do receptors work in the endocrine system?

A

Hormone works by binding to specific receptors on surfaces of cell or inside the cell.

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6
Q

What are tropic hormones?

A

Tropic hormones actions are specific for another endocrine gland.
E.g. Anterior pituitary releases Adrenocorticotropic Hormone (ACTH) that acts on adrenal glands.

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7
Q

What are direct effector hormones?

A

Direct effector hormones act on peripheral tissues.

E.g. Growth hormone.

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8
Q

What substance whose levels in blood regulates insulin release?

A

Glucose levels in blood affect insulin release.

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9
Q

What is the link between the nervous system and the endocrine system?

A

Hypothalamus is the nervous system component that links with the endocrine system.

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10
Q

List some tropic hormones (3) of the anterior pituitary gland.

A

LH
FSH
TSH

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11
Q

What is negative feedback?

A

Think of an analogy to the thermostat & furnace. As temp falls, thermostat sends electrical impulse to furnace to come on and restore heat. But when temp is high enough the thermostat turns off signal and furnace stops.

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12
Q

What is an open-loop negative feedback system?

A

An open-loop negative feedback system is influenced or modified by neural input or other hormones.

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13
Q

Give an example of an open-loop negative feedback system?

A

TRH (Thyrotropin-Releasing Hormone) produced by hypothalamus and causes anterior pituitary to secrete TSH
TSH travels to thyroid stimulates release of thyroxine (FT4)
Thyroxine (FT4) in blood circulates to hypothalamus and suppresses the pituitary from further TRH and TSH production

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14
Q

What is positive feedback?

A

In response to a hormone increasing in levels another hormone (or other response) also increases in levels.
E.g. Menstrual cycle:
Estrogen –> Increased & LH –> Increased

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15
Q

What endocrine gland does the hormone ACTH (Adrenocorticotropic Hormone) impact and the effect?

A

ACTH –> Adrenal Cortex.

Effect: Produced in times of stress. Stimulates secretion of glucocorticoids.

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16
Q

What endocrine gland does the hormone TSH (Thyroid Stimulating Hormone) impact and the effect?

A

TSH –> Thyroid Gland

Effect: Stimulates secretion of thyroid hormones. Increases metabolism by cells in body.

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17
Q

What endocrine gland does the hormone LH (Luteinizing Hormone) & FSH (Follicle Stimulating Hormone) impact and the effect?

A

LH & FSH –> Ovaries and Testes

Effect: Control of reproductive function (menstrual cycle and leads to sperm production).

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18
Q

What hormone impacts the liver and other tissues to stimulate cell development, growth and regeneration?

A

Growth Hormone.

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19
Q

What hormone stimulates milk production in what glands?

A

Prolactin impacts the mammary glands for milk production.

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20
Q

What hormone is released by the posterior pituitary but produced by the hypothalamus in birth? To do what? What else does it do?

A

Oxytocin to stimulate uterine contractions.

It also is released during mom/baby bonding and during milk production.

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21
Q

What is the effect of ADH (Antidiuretic Hormone or Vasopressin) and what does it act on & why?

A

Acts on kidneys and blood vessels to reduce blood pressure for:

  1. The conservation of body water by increasing reabsorption of water by the renal tubules.
  2. Released with decreased blood volume or an increase in sodium.
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22
Q

What hormone plays a role in diabetes insipidus? What are the resulting symptoms?

A

Diabetes in insipidus is an imbalance of fluids due to decreased production or a decreased response to ADH. Results in extreme thirst and large amounts of urine production.

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23
Q

List the various zones of the adrenal glands and the hormones they release.

A

Slide 10.

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24
Q

At what times does ACTH and cortisol levels show diurnal peaks & troughs at?

A

Slide 11

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25
How is ACTH specimen to be collected?
1. Collected in a chilled EDTA tube and put on ice. | 2. Collect between 0800 and 1000h, record exact time of collection.
26
What are the adult reference ranges for ACTH and cortisol including time ranges?
Slide 11.
27
What does ACTH do?
Slide 11 - reminder.
28
What is Cushing's syndrome?
Excess cortisol over a prolonged period of time Symptoms: fatty hump between your shoulders, a rounded face, and pink or purple stretch marks on your skin. Cushing syndrome can result in high blood pressure and bone loss
29
What is Addison's disease? What hormones impact it, the symptom's and its treatment?
Addison’s Disease (or Primary Adrenal Insufficiency): ↓cortisol and N or ↑ ACTH Adrenal glands produce too little cortisol and aldosterone Result of damage, underactive, infection, cancer Symptoms: fatigue, weight loss, salt craving, vomiting, dehydration, and diarrhea Treatment: life-long gluco- and mineralocorticoids
30
What produces thyrotropin-releasing hormones and what do they do?
Thyrotropin-releasing hormones is produced by neurons in the hypothalamus. Stimulates the release of thyroid-stimulating hormone from the anterior pituitary.
31
What is TSH?
TSH (Thyroid Stimulating Hormone): From anterior pituitary. It stimulates the release of thyroid hormones. Will feedback and inhibit further release of TSH.
32
How is thyroid hormone measured?
Thyroid hormone is measured as Free T3 or Free T4.
33
What is T3 (Triiodothyronine) and T4 (Thyroxine)? Compare the T3 to T4.
T3 (Triiodothyronine) and T4 (Thyroxine) Regulate body temperature, metabolism, neurological development, and heart rate T4 is more abundant than T3 (9:1) T3 is far more metabolically active than T4
34
What are Free T3 and Free T4?
Free T3 (FT3) and Free T4 (FT4) are the biologically active hormone forms (NOT bound to proteins).
35
What hormones does the thyroid produce?
T3 and T4 | Calcitonin.
36
What does calcitonin do?
Calcitonin: 1. Reduce levels of calcium and phosphate in the blood 2. Opposes effect of PTH (Parathyroid Hormone)
37
What is hyperthyroidism?
Hyperthyroidism: ↓TSH and ↑ or normal FT4 Increased metabolism, weight loss, heat intolerance, muscle weakness, psychosis, restlessness, tachycardia, etc.
38
What is Graves' Disease?
Graves’ Disease is an autoimmune disorder that results in an enlarged thyroid and increased secretion of FT4.
39
What are the symptoms and treatment of hypothyroidism?
Symptoms - Decreased metabolism, weight gain, cold intolerance, depression, lethargy, infertility, etc. Treatment – thyroxine to normalize TSH levels
40
What causes Hashimoto's disease?
Hashimoto’s disease results from autoantibodies attacking the thyroid gland causing it to become inflamed and no longer able to produce thyroid hormones
41
How are the levels of TSH and FT4 affected with primary Hypothyroidism?
Primary Hypothyroidism-->Thyroid dysfunction-->↑TSH; ↓ FT4
42
How are the levels of TSH and FT4 affected in secondary hypothyroidism?
Secondary Hypothyroidism-->Pituitary dysfunction-->Normal or TSH ↓; ↓ FT4
43
What is the adult reference ranges for TSH?
0.4-4.2 mU/L
44
What will abnormal TSH reflex to?
Abnormal TSH will reflex as follows: Free T4 performed when TSH < 0.40 mU/L and ≥ 4.3 mU/L Free T3 performed when TSH < 0.09 mU/L
45
What are the reference ranges for FT4 and FT3?
FT4: 9.7-25.7 pmol/L FT3: 3.7-6.9 pmol/L
46
What is the preferred specimen for testing thyroid function?
Plasma is the preferred specimen type.
47
What is the most useful test for assessing thyroid function?
Measuring TSH.
48
What lab methods are used for testing of thyroid function?
RIA, ELISA, IRMA, CLIA.
49
Case Study: A 56 year old man tells his doctor that he has been feeling very lethargic and has gained weight lately, but has chalked it up to getting older. His doctor finds that the man has dry skin and a slow heart rate. His TSH is normal but FT4 is decreased. What could his condition be?
The patient’s symptoms matched those of hypothyroidism and the laboratory results confirmed the diagnosis. The patient was put on thyroxine replacement therapy and responded well. His renewed energy made him feel younger than he had in a long while.
50
Case Study: A 39 year old female came to her doctor with tiredness, muscle pain and weakness, diarrhea and weight loss. She had an enlarged thyroid gland and exophthalmos. ↓TSH and ↑FT4 and TRAB is positive.
↓TSH and ↑FT4 = hyperthyroidism But why??? Thyroid Receptor Antibodies (TRAb) - Indicates thyroid status of patient TRAb stimulates TSH receptors causing excess production of FT4 Presence of TRAb indicates Graves Disease Treatment options are the drug carbimazole, radioactive iodine or surgery
51
Where is PTH (Parathyroid hormone) formed and what does it do?
PTH (Parathyroid hormone) Formed in parathyroid glands (posterior of thyroid gland) Together with vitamin D and calcitonin, PTH maintains a balance of calcium and phosphate in the blood PTH ↑ levels of calcium and phosphate in the blood from the skeletal system Calcitonin ↓ calcium and phosphate levels in circulation PTH will be suppressed with hypercalcemia
52
What reason is PTH (Parathyroid hormone) typically measured for?
Parathyroid hormone (PTH) concentration is routinely measured in the diagnosis and management of bone and kidney diseases
53
What can be the result of parathyroid disorders?
Parathyroid disorders can lead to hypercalcemia or hypocalcemia Necessary to assess calcium levels at the same time as PTH levels for proper clinical interpretation E.g. Is it: Hypercalcemia, hypoparathyroidism or hyperparathyroidism
54
What can cause an increased in PTH?
Tumour.
55
Case Study: A 51 year old man was having trouble urinating and was found to have calcium containing calculi. His Ca, Phos, and PTH were above the reference ranges. What could be his condition?
Patient was diagnosed with hyperparathyroidism ↑PTH and ↑Ca PTH concentration and calcium should be investigated together ↑ calcium in blood, deposits in kidneys, leads to kidney stones
56
How should we refer to patients for phlebotomy considering gender sensitivity?
1. Calling patients for phlebotomy a) Don’t use Mrs, Mr, Miss, etc. b) Use a numbering system instead of calling people by their current legal name to avoid “outing” them to the waiting room 2. Providing instructions for urine collection: Use general terms that can be applied to all individuals yet ensuring proper sample integrity. Have additional supplies in the bathroom for collection needs 3. Interpreting results: Female versus male values, Hormone Replacement Therapy (HRT) and its alteration in biomarker values Considerations for Inclusion of Gender Diversity within Medical Laboratory Services Anatomical interpretations – cytology, genital swabs in Micro, etc.
57
Is it significant for the lab to know if someone is trans?
Only info we need is for our job. So if you don't need to know, don't snoop. All patients should fee safe and included. Consider the impact on patients and their future interactions with the healthcare system.
58
List the five biological sex female hormones.
``` FSH Follicle stimulating hormone LH Luteinizing hormone. B-hCG - Human chorionic gonadotropin. Estrogen Estradiol Progesterone. ```
59
What does FSH and LH do for a female? Test purposes?
1. FSH (Follicle Stimulating Hormone) and LH (Luteinizing hormone) - stimulates the growth and maturation of ovarian follicles ``` 2. FSH and LH tests are used to: Evaluate and manage hypogonadism Menstrual irregularities Infertility investigation Diagnosis of pituitary disorders ```
60
What and when is B-hCG produced? Why is it assessed?
Β-hCG (human chorionic gonadotropin) – produced by the placenta during pregnancy Assessment: Pregnancy hCG secreting hormones
61
What does estrogen do?
Estrogen – development and regulation of the female reproductive system and secondary sex characteristics
62
What does estradiol do? Why is it tested?
Estradiol – development of female secondary sex characteristics, regulation of the menstrual cycle, breast and uterine growth, and the maintenance of pregnancy. Estradiol is used to assess ovarian status.
63
What does progesterone do? What organ secretes it? What is it tested for?
Progesterone – secreted by corpus luteum (part of cells in ovary) to prepare the uterine mucosa for implant of a fertilized ovum and inhibits contraction of the myometrium to help support pregnancy. Tested in the investigation of fertility.
64
What is the purpose of FSH,LH and testosterone in a male? What is it tested for?
FSH and LH – testes growth and stimulate sperm development | Testosterone – development of male reproductive tissues (testes and prostate) and secondary male sex characteristics
65
Can you apply the same reference ranges for sex hormones throughout someone's life?
Levels of hormones change with the ages and stages of life. Refer to slides 25 and 26.
66
Why is FSH and LH tested in males?
Tested for the same reasons as for females.
67
Why is testosterone tested in males?
Assessment of testosterone for: Evaluation of infants with ambiguous genitalia Evaluation of boys with delayed puberty Monitoring of testosterone replacement or antiandrogen therapy Female infertility Diagnosis of androgen-secreting tumors
68
Case Study: A 20 year old young man presented with impotence. It was found that he had never developed through adolescence. His Testosterone was low, LH and FSH were also low. Why did this occur to him?
1. Sometimes delayed puberty occurs, but in this case the patient is hypogonadal. The cause of this could be pituitary or hypothalmic. 2. After testing, the testosterone deficiency in this case was found to be hypothalmic. The hypothalmus has an influence on the pituitary gland.
69
What is the Human Chorionic Gonadotropin (HCG) hormone and when is it measured?
Hormone produced by placenta in the first trimester of pregnancy Appears in urine and plasma ~ 10-12 days after fertilization HCG measured in urine or serum to confirm pregnancy HCG levels rise for first 9 weeks of pregnancy then decline to a certain level for rest of pregnancy
70
Why is HCG preferred to be sampled first thing in the morning?
More concentrated then, so easier to detect the low levels of the hormone.
71
What techniques are used to analyze for HCG?
Hormone acts as antigen and reacts with reagent antibody Lateral flow – qualitative (positive or negative) Immunoassay analyzer – quantitative (concentration)
72
Can someone have HCG positive results outside of pregnancy?
HCG Positive results can occur outside of pregnancy: | Hydatidiform mole, choriocarcinoma, and HCG secretion tumours
73
What can cause false negatives in a pregnancy test?
False negative results can occur if urine is too dilute or if sample is collected too early in pregnancy.
74
What are reasons HCG is tested?
1. Pregnancy 2. Ectopic pregnancy – HCG fails to rise at expected rate 3. Threatened abortion - assessing fetal viability 4. Spontaneous abortion or miscarriage – slowing rate of HCG increase and decline in HCG levels as miscarriage takes place 5. Tumour marker – diagnosis and monitoring of certain cancers (This is why HCG may be looked at in men).
75
What are the advantages of a (home) pregnancy test?
Simple, quick, and reliable Low sample volume Store at room temperature Generally has a long shelf life
76
How does a home pregnancy test work?
HCG hormone in urine is drawn in dipstick by capillary action. It binds to the detection antibody on the stick which gets bound to the capture antibody. There are two locations where there are capture antibodies: 1) captures Detection Ab with HCG and 2) the other already has HCG on it and captures the detection antibody to prove it is working. (Check my explanation but this is how I understand it). Interpret: Two colour strips means the person is pregnant but if only one colour strip they are not.

Clinical Chemistry 1 (11 decks)

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