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Chem Path Flashcards

0
Q

Functions of cortisol

A
  • antagonises insulin
  • causes proteolysis (prod of amino acids)
  • anti-inflam
  • suppresses immune system
  • antagonises vit D to reduce calcium absorption
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1
Q

Functions of aldosterone

A
  • promotes sodium and water retention

- k and h excretion

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2
Q

Hormones produced by the cortex of the adrenal gland

A

Corticosteroids
Glomerulosa - mineralocorticoids - aldosterone
Fasiculata - glucocorticoids - cortisol
Reticularis - androgens - DHEA

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3
Q

Hormones produced by adrenal medulla

A

Catecholamines (E and NE)

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4
Q

Describe steroid synthesis

A
  • produced from cholesterol
  • rate limiting step = chol side-chain cleaved to pregnenolone (stim by ACTH)
  • hydroxylations require cyt-p450 in mitochondria
  • 17 and 21 hydroxylations occur in sER
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5
Q

Why is aldosterone not affected by decrease in ACTH?

A

Stimulated mainly be ang2 and k

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6
Q

Characteristics of CBG

A
  • made by liver
  • high affinity
  • low capacity
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7
Q

Characteristics of albumin

A
  • low affinity

- high capacity

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8
Q

Why does aldosterone have a shorter half life.

A

Not bound to plasma protein

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9
Q

3 catecholamine hormones

A
  • dopamine
  • epinephrine
  • norepinephrine
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10
Q

Action of alpha adrenergic receptors

A
  • vasoconstriction
  • decreased insulin release
  • sweating
  • glycogenolysis
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11
Q

Action of beta adrenergic receptors

A
  • vasodilation
  • increased HR
  • intestinal smooth muscle relaxation
  • bronchodilation
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12
Q

Synthesis of catecholamines

A
  • from phenylalanine
  • rate limiting. = tyrosine to DOPA
  • hormones in adrenal medulla are complexed to chromogranin proteins in granules
  • nerve stim causes granule release
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13
Q

How are catecholamines degraded?

A
  • catechol-O-methyl transferase (COMT) - methylation

- mono amine oxidase (MOA) - deamination

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14
Q

Pattern of inheritance of CAH

A

Autosomal recessive inborn errors of steroid hormone biosynthesis

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15
Q

Most common defect in CAH

A

21 hydroxylase

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16
Q

Mechanism of 21 hydroxylase deficiency

A
  • can’t synthesize cortisol so increased ACTH (adrenal hyperplasia)
  • accumulation of 17- hydroxyprogesterone (shunting to androgen synthesis)
  • elevated 17OHP in serum confirms
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17
Q

3 forms of CAH

A
  • simple virilising
  • severe salt-losing
  • non-classical
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18
Q

Characteristics of simple virilising form

A
  • mild enzyme defect

- adequate cortisol and aldosterone production

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19
Q

Characteristics of sever salt-losing form

A
  • severe enzyme defect
  • potential adrenal crisis due to inadequate aldosterone
  • hypotension, shock, hyperkalaemia
  • boys more at risk
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20
Q

Characteristics of non classical form

A
  • very mild defect
  • no neonatal masculinization
  • young women present with menstrual irregularities, infertility and hisuitism
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21
Q

Treatment of CAH

A
  • cortisol and fludrocortisone

- monitor by measuring 17OHP and androgens

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22
Q

Characteristics of 11hydroxylase deficiency

A
  • accumulated 11 deoxycortixosterone has mineralocorticoids activity
  • salt retaining
  • hypertension and hypokalaemia
  • ambiguous genitalia
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23
Q

Diagnosis of CAH

A
  • elevated serum 17OHP or 11DOC
  • decreased serum cortisol
  • elevated serum ACTH
  • elevated serum testosterone
  • karyotyping
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24
Definition of primary Addison's disease
- impaired capacity to secrete cortisol and aldosterone
25
Definition of secondary Addison's disease
- lack of ACTH - cortisol deficiency - intact aldosterone e
26
Features of an addisonian crisis
- hypotension - circulatory shock - abdominal pain
27
Clinical features of Addison's
- fatigue - muscle weakness - orthostatic hypertension - pigmentation (excess ACTH)
28
Biochem features of Addison's
Aldosterone deficiency - Na and water loss in urine - hyperkalaemia and metabolic acidosis Cortisol deficiency - inability to excrete water load - hypoglycemia
29
Key diagnostic features of Addison's
- orthostatic hypotension - low Na - high k
30
Hormonal changes at puberty
- adrenarche (adrenal androgen secretion) - decreased sensitivity of axis - increased ovarian oestradiol secretion
31
Events of peri-menopause
- FSH rises 1-2 years before - LH initially unchanged - oestrogen normal til few months before
32
Why more free testosterone in pcos?
Androgens and insulin suppress hepatic shbg synthesis
33
Causes of hisuitism
- idiopathic - drugs (anabolic steroids) - ovarian (pcos) - adrenal (CAH) - Cushing's syndrome
34
Commonest tumours associated with tumour lysis syndrome
- burkitts and ALL | - solid tumours that are bulky with extensive metastasis
35
Modified Howard definition of TLS
2 or more of the following metabolic abnormalities Occurring simultaneously within 3 days prior and up to 7 days after initiation of treatment - hyperuricaemia - hyperkalaemia - hyperphosphataemia - hypocalcaemia
36
Two factors in TLS that can cause renal failure
- hyperuricosuria (acute Uric acid nephropathy) | - hyperphosphataemia (calcium phosphate crystals in renal parenchyma)
37
Prevention of TLS
- suspect and anticipate - adequate IV hydration - prophylactic allopurinol
38
Treatment f TLS
- watch renal function - hydration - reduce Uric acid with allopurinol - correct electrolyte abnormalities
39
3 pathways supplying cells with bases, nucleosides and nucleotides
- salvage - degradation - de novo synthesis
40
Define gouty to phi
Depositions of mono sodium urate crystals in joints, cartilage, bones, skin and other sites
41
Definition of gout
Acute painful arthritis in a single joint due to deposition of Uric acid crystals
42
Diagnosis of gout
- clinical features - Uric acid crystals in joint fluid aspirate is definitive - elevated plasma Uric acid is suggestive
43
Causes of gout
- under excretion (renal insufficiency) - overproduction (malignancy, obesity) - over-consumption (meat, alcohol)
44
Treatment of gout
- colchicine to reduce acute pain - allopurinol to reduce Uric acid formation - uricosurics to increase Uric acid excretion
45
Definition of multiple myeloma
Malignant proliferation of a clone of plasma cells
46
Pathogenesis of multiple myeloma
When one clone of plasma cells becomes malignant, the expansion of this clone suppresses the formation of other clines - overproduction of a single monoclonal antibody
47
Features of myeloma
- bone marrow infiltration (osteolytic lesions, bone pain) - hypercalcaemia (due to osteoclast activity) - bone marrow suppression (anaemia) - monoclonal protein production (elevated ESR, hyper viscosity)
48
Lab features of myeloma
- high total protein - monoclonal antibody on serum protein electrophoresis - suppression of other immunoglobulins - sometimes free light chains in urine (bench jones proteinuria)
49
Hormones that increase plasma glucose
- glucagon - adrenaline - GH - cortisol
50
Hormones that decrease plasma protein
- insulin
51
Diagnosis of HbA1c
Non-enzymatic covalent glycation of the N terminal valine on the b-chain of Hb
52
Methods of diabetes diagnosis
- fasting plasma glucose levels - glucose tolerance test - hba1c
53
Methods of monitoring diabetes
- plasma glucose - urine glucose - plasma ketones - urine ketones - hba1c
54
Diagnosis of DKA
- decrease PH | - increase glucose and ketones
55
Diagnosis of honk
- increase glucose and osmolarity - no ketones PH decrease
56
3 thyroid hormones
- thyroxine - triiodothyronine - calcitonin
57
Thyroid hormone function
- bind in nucleus - necessary for physical growth and development - oxygen consumption and ATP hydrolysis increased in mitochondria - effects on hormones (enhances insulin action)
58
Factors that increase TBG
Oral contraceptive pill | Pregnancy
59
Factors that decrease TBG
Protein losing states Malnutrition Corticosteroids
60
Tumour marker for thyroid cancer
Thyroglobulin
61
Tumour marker for medullary thyroid cancer
Calcitonin
62
Changes seen in sick euthyroid syndrome
- decreased peripheral conversion of T4 to T3 - changes in conc/affinity of binding proteins - disturbances in axis
63
Common causes of Addison's disease
- autoimmune - TB - Neoplastic infiltration - haemochromatosis - adrenoleukodystrophy - CAH
64
Functions of oestrogen
- female secondary sex characteristics - bone growth - uterine thickening - breast development
65
Functions of progesterone
- promotes secretions of uterus - implantation of ovum - maintenance of early pregnancy
66
How can oestrogen be carried in blood?
- 60% albumin - 38% SHBG - 2% free
67
When is progesterone at max and what is it used for?
At day 21 | Tests ovulation
68
Causes of amenorrhea
- disorders of uterus - disorders of the ovary (hypergonadotropic) - disorders of pituitary (hypogonadotropic) - CNS disorders
69
Features of PCOS
- menstrual irregularities - hyperandrogenism - obesity - insulin resistance - multiple follicles
70
Hormone levels in pcos
- androgens elevated - oestradiol normal - LH high - FSH normal

March Exams (14 decks)

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