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203: Theme 1: The Endocrine System > Hypothalamic- pituitary- adrenal axis: clinical aspects > Flashcards

Hypothalamic- pituitary- adrenal axis: clinical aspects Flashcards

1
Q

Adrenal cortex hormone production

A

Glucocorticoid
- cortisol

Mineralocorticoid
- aldosterone

Sex steroids
- androgens

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2
Q

Binding proteins

A

90% cortisol bound to cortisol binding globulin

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3
Q

Receptors

A

Intracellular glucocorticoid and mineralocorticoid receptors

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4
Q

Enzymes

A

11- beta- hydroxysteroid dehydrogenase

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5
Q

Effects of glucocorticoids

A

Maintenance of homeostasis during stress (e.g. haemorrhage, infection, anxiety)

Anti-inflammatory

Energy balance/ metabolism

Formation of bone and cartilage

Regulation of blood pressure

Cognitive function, memory, conditioning

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6
Q

Circadian rhythm: cortisol levels

A

Rise during the early morning

Peak just prior to awakening

Fall during the day

Are low in the evening

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7
Q

Ultradian rhythm

A

Spontaneous pulses of varying amplitude

Amplitude decreases in the circadian trough

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8
Q

11-B-HSD enzymes

A

Tissue specificity:

  • gating of GC access to nuclear receptors
  • amplification of GC signal in target cells
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9
Q

Too much cortisol causes

A

Cushing’s syndrome

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10
Q

Features of Cushing’s syndrome

A

Weight gain

Central obesity

Hypertension

Insulin resistance

Neuropsychiatric problems

Osteoporosis

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11
Q

Pathogenesis of Cushing’s syndrome

A

Excess cortisol

  • pituitary adenoma: ACTH secreting cells
  • adrenal tumour: adenoma
  • ectopic ACTH: carcinoid, paraneoplastic
  • iatrogenic: steroid treatment
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12
Q

Clinical features of Cushing’s syndrome

A

Central obesity with thin arms and legs

Fat deposition over upper back

Rounded moon face

Thin skin with east bruising, pigmented striae

Hirsutism

Hypertension

Diabetes

Psychiatric manifestations

Osteoporosis

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13
Q

Too little cortisol

A

Addison’s disease

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14
Q

Pathogenesis of Addison’s disease

A

Primary adrenal insufficiency

  • usually autoimmune in UK
  • rare causes include metastases or TB
  • decreased production of all adrenocortical hormones

Other causes of hypoadrenalism

  • secondary to pituitary disease
  • iatrogenic
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15
Q

Clinical features of Addison’s disease

A

Malaise, weakness, anorexia, weight loss

Increased skin pigmentation (knuckles, palmar creases, around/ inside the mouth, pressure areas, scars)

Hypotension/ postural hypotension

Hypoglycaemia

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16
Q

Type 1 autoimmune polyendocrine syndromes

A

Rare

Onset in infancy

Ar (AIRE gene)

Common phenotypes

  • Addison’s disease
  • hypoparathyroidism
  • candidiasis
17
Q

Type 2 autoimmune polyendocrine syndromes

A

Commoner

Infancy to adulthood

Polygenic

Common phenotype

  • Addison’s disease
  • T1 diabetes
  • autoimmune thyroid disease
18
Q

Autoimmune conditions that may occur together

A

Type 1 diabetes

Autoimmune thyroid disease

Coeliac disease

Addison’s disease

Pernicious anaemia

Alopecia

Vitiligo

Hepatitis

Premature ovarian failure

Myasthenia gravis

19
Q

Clinical implications of autoimmune polyendocrine syndromes

A

High index of suspicion for additional autoimmune endocrine disorders

Consider screening in patients with T1 DM and or/ Addison’s disease

  • coeliac screen
  • thyroid function tests
20
Q

Assessment of the HPAA

A

Basal

  • blood: cortisol, ACTH
  • urine: cortisol
  • saliva: cortisol

Dynamic tests

  • stimulated
  • suppressed
21
Q

Two golden rules

A

Never start investigations for an endocrine condition unless symptoms and signs suggest they have it

Never image any endocrine gland until you have established the diagnosis biochemically

22
Q

Imaging

A

Once you have confirmed that a patient has Cushing’s syndrome, consider

  • CXR
  • MRI pituitary
  • CT adrenals

Patients with Addison’s disease seldom need imaging unless you are concerned they may have TB/ metastatic cancer

23
Q

Management of Cushing’s syndrome

A

Surgical (depending on the cause)

  • transphenoidal adenectomy
  • adrenalectomy

Pituitary radiotherapy

24
Q

Management of Addison’s disease

A

Steroid hormone replacement therapy

Patients with primary adrenal insufficiency also need mineralocorticoid replacement therapy

Patients with secondary adrenal insufficiency will often be taking other hormone replacement therapy

25
Q

Patients taking steroids

A

May be treated with long term high dose steroids for many reasons

  • glucocorticoids
  • usually prednisolone

Usually the steroids are being used for their anti-inflammatory/ immunosuppressive effects

Conditions include severe asthma/ COPD, temporal arteritis/ polymyalgia rheumatica

203: Theme 1: The Endocrine System (22 decks)

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