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MP322 > week 11 > Flashcards

week 11 Flashcards

1
Q

What can hypothyroidism be treated with?

A

levothyroxine
30mins before breakfast and caffeine containing liquids.
liothyronine
carbimazole

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2
Q

Where are thyroid hormones produced?

A

thyroid gland by the thyroid follicles

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3
Q

Colloid

A

proteinaceous depot of thyroid hormone precursors

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4
Q

Synthesis of thyroid hormones

A

1) Iodine co-transported with Na+.
2)Diffusion into follicle cell.
3)Iodine transported to colloid, oxidized and attached to rings of tyrosine’s in TG. (thyroglobulin)
4)Iodinated ring is added to a DIT at another spot.
5)Endocytosis of TG
6)Lysosomal enzymes release T3 and T4 from TG.
7)T3 and T4 are released from cell

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5
Q

What is the most active thyroid hormone?

A

T3

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6
Q

How is T4 changed to T3

A

deiodination

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7
Q

How is thyroid hormone secretion controlled?

A

Hypothalmus———————————————————–
Thyrotophin-releasing hormone TRH secretion I
Anterior pituitary—————————————————–
Thyroid-stimulating hormone TSH secretion I Thyroid gland I
Thyroid hormone (secrettion) ———————————-
Targtet cell responce

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8
Q

Euthyroid state

A

Thyroid hormone secretion is normal

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9
Q

Hypothyroid state

A

Thyroid hormone secretion is subnormal

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10
Q

Hyperthyroid state

A

Thyroid hormone secretion is excessive

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11
Q

Actions of thyroid stimulating hormone

A

stimulate T3 and T4 production
increases protein synthesis
increases DNA replication and cell division
increases rough endoplasmic reticulum and cell machinery required for protein synthesis.

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12
Q

What causes a goitre?

A

hypothyroidism, hyperthyroidism and euthyroidism, excessive exposure to TSH.

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13
Q

Actions of T3 and T4 hormones

A

T4 secreted to T3
Increased basal metabolic rate, heat production, growth and development, maintenence of normal activity

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14
Q

What are the effects of an iodine deficiency?

A

Metal retardation, reduction in physical growth, deaf-mutism, cretinism (rare)

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15
Q

Iodine RDA

A

150 mcg/day

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16
Q

TSH and T4 levels in correspondance to;
Normal
Hyperthyroidism
Hypothyroidism primary
Hypothyroidism secondary

A

TSH normal T4 normal
TSH low T4 high
TSH high T4 low
TSH low T4 low

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17
Q

Signs and symptoms of hypothyroidism

A

cold intolerance, weight gain, tiredness, bradycardia, constipation, depression, pale dry skin, puffy face

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18
Q

Hashimoto’s thyroidism

A

autoimmune disorder and the main cause of hypothyroidism.
Self-reactive T lymphocytes recruit B cells and T cells into the thyroid.
B cells produce antibodies of thyroid epithelial cells. T cells become cytotoxic T lymphocytes leading to cells destruction and decreased production of the thyroid hormones.
T4 decreases and TSH increases

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19
Q

Is Hashimotos more common in men or women?

A

twice as prevalent in women

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20
Q

Treatment of Hashimoto’s/primary hypothyroidism. Side effects?

A

Levothyroxine - synthetic T4.
Hair loss, headaches, sleep problems, nervousness, fever, pounding heart, appetite changes

Liothyronine - synthetic T3.
Risks of osteoporosis and heart arrythmia.
shorter half-life

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21
Q

Secondary hypothyroidism

A

uncommon
pituitary doesn’t produce TSH or hypothalamus doesn’t produce sufficient TRH.
T3 T4 and TSH are below normal

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22
Q

What may happen as a result of untreated hypothyroidism?

A

Myxoedema coma
extreme hypothermia (24-32C), seizures, respiratory depression

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23
Q

Drugs effecting thyroid function

A

Corticosteroids - decreased production of TRH and TSH
Lithium - inhibits release of T3 and T4
Amiodarone - contains iodine and can cause hypo and hyperthyroidism
Cholestyramine - reduces absorption of thyroxine

24
Q

Signs of hyperthyroidism

A

heat intolerance, palpitations, weight loss, restlessness, fatigue, sweating, frequent bowel movement, goitre

25
Q

Cause of hyperthyroidism

A

thyroid produces excess of T4, reduction in TSH due to negative feedback loop.
T3 also elevated.

26
Q

Graves disease

A

most common cause of hyperthyroidism
caused by TSI - thyroid stimulating immunoglobulin which increases secretion of thyroid hormones
autoimmune disease

27
Q

Treatment of hyperthyroidism

A

Surgery, radioactive iodine - administered orally.

28
Q

Antithyroid drugs

A

Thioamides (carbimazole, propylthiourcail)
inhibit thyroid peroxidase and prevent hormone synthesis.
Effect of onset is slow - increased risk of infection.

29
Q

What is the difference in chemical structure of T3 and T4

A

T4 has an extra iodine

30
Q

How are T4 and T3 transported around the body?

A

Bound to proteins in the blood.

31
Q

Levothyroxine logP and pKa

A

logP 7.4 and pKa 10, 9 ,4

32
Q

Liothyronine logP and pKa

A

LogP 6
pKa 10,9,4

33
Q

How does carbimazole work?

A

a prodrug in which the active form inhibits thyroid peroxidases which convert tyrosine into MIT and DIT. = no T3 and T4. Log P of carbimazole 0.3, LogP of methimazole -0.3.

34
Q

Hormones secreted by the adrenal glands.

A

Adrencorticoids, minerlacorticoids, glucocorticoids, sex hormones, adrenaline, noradrenaline

35
Q

What are mineralocorticoids? Give example

A

Aldosterone
Made in Zona glomerulosa
Important for Na+ reabsorption and K+ excretion in kidneys.

36
Q

What are glucocorticoids? Give example

A

Cortisol
Made in the Zona fasciculata
Regulate body’s response to stress, also help regulate glucose levels.

37
Q

What are sex hormones? Give example

A

Androgens
Synthesized in Zona reticularis
Regulate reproductive function

38
Q

What is cortisol secretion controlled by?

A

hypothalamic pituitary adrenal axis

39
Q

Cortisol secretion

A

stress
hypothalamus ——————————————————–
corticotrophin-releasing hormone (CRH) secretion I
anterior pituitary —————————————————
adrenocorticotrophic hormone (ACTH) secretion I
adrenal cortex I
cortisol —————————————————————–
target cell response

40
Q

Factors increasing cortisol production

A

sleep deprivation, trauma, extreme fasting

41
Q

When does cortisol release peak values?

A

upon waking - diurnal variation

42
Q

Cellular actions of cortisol

A

increases circulating glucose levels
maintains responsiveness of blood vessels to vasoconstrictive stimuli
can have anti-inflammatory action

43
Q

What effect does an increased level of cortisol have of plasma levels of glucose, fatty acids and amino acids

A

increases them

44
Q

What is Addison’s disease?

A

adrenocortical insufficiency
primary adrenal insufficiency
due to destruction or dysfunction of the adrenal cortex, effects both mineral and glucocorticoid function.

45
Q

Symptoms of Addison’s disease.

A

darkening of the skin
extreme fatigue
weight loss and reduced appetite
low blood pressure
GI distrubance
salt craving
low blood glucose

46
Q

Causes of Addison’s disease

A

Infections, invasion, haemorrhage

47
Q

What impact does Addison’s disease have on the cortisol flow chart?

A

decreased secretion of cortisol due to negative feedback
increased secretion of corticotrophin releasing hormone and adrenocorticotrophic hormone.

48
Q

What is it that causes hyperpigmentation in Addison’s disease?

A

increased levels in adrenocorticotrophic hormones that constantly stimualte melanocytes.

49
Q

Treatment of Addison’s

A

Hydrocortisone (sometimes prednisolone or dexamethasone) 15-30mg
Fludrocortisone (mineralocorticoid)

50
Q

Secondary adrenal insufficiency and treatment

A

Lack of ATCH secretion from pituitary
Don’t show hyperpigmentation or salt craving.
Can occur if glucocorticoid medication is stopped too abruptly
Treatment; glucocorticoid e.g. hydrocortisone, mineralocorticoid is unnecessary as the gland itself is not damaged.

51
Q

Tertiary adrenal insufficiency

A

Lack of corticotrophin releasing hormone secretion from the hypothalamus

52
Q

How do glucocorticoid drugs work?

A

Suppress hypothalamus and anterior pituitary.
Anti-inflammatory’s = predinsolone, dexamethasone, hydrocortisone, beclamethasone

53
Q

Adrenal crisis symptoms

A

sudden severe pain in lower back, severe vomiting and diarrhoea, dehydration, low blood pressure, loss of consciousness

54
Q

What is cushing’s syndrome? What are the symptoms

A

Hypersecretion of cortisol.
red cheeks, moon face, fat pads, thin skin, red striations, high blood pressure, thin arms and legs, pendulous abdomen, poor wound healing

55
Q

Causes of Cushing’s disease

A

pituitary tumor
adrenocortical tumors

56
Q

What are the two classes of Cushing’s syndrome?

A

Adrenocorticotrophic (ACTH) dependent; body making too much ACTH due to pituitary or ectopic tumor

Adrenocorticotrophic (ACTH) independent; ACTH level too low, Adrenal glands making too much cortisol due to adrenal tumor

57
Q

What drug interactions may cause Cushing’s syndrome?

A

Drugs that inhihibt P450 enzymes as they prolong the action of glucocorticoids
e.g. many antidepressants, itraconazole, ritonavir

MP322 (5 decks)

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