CHEMPATH: Adrenal Disease Flashcards

1
Q

What are the layers of the adrenals ?

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2
Q

Case 1: What is the diagnosis? What do the electrolytes indicate?

  • 31yo, profound fatigue, acutely unwell for a few days, vomiting
  • Test results:
    • Na = 125
    • K = 6.5
    • U = 10
    • Glucose = 2.9mM
    • FT4 = <5nM
    • TSH = >50mU/L
A
  • TSH and T4 measurements = primary hypothyroidism (or thyroid failure)
  • Hypothyroidism does not explain unusual electrolutes. Deficiency of mineralocorticoid and glucocorticoid because:*
  • Unusual U&Es (hyponatraemia and hyperkalaemia) = Mineralocorticoid deficiency
  • Hypoglycaemia = Glucocorticoid deficiency

Both = Addison’s disease

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3
Q

Addison’s disease + primary hypothyroidism =?

A
  • Schmidt’s syndrome
    • AKA: Polyglandular autoimmune syndrome type II
    • Antibodies against the thyroid and adrenal glands
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4
Q

What is the test for Addison’s disease?

A

Short SynACTHen test:

  • 1) Measure cortisol and ACTH at start
  • 2) 250ug ACTH, IM
  • 3) Check cortisol at 30 and 60 minutes

Results in the previous patient case:

  • ACTH = >100ng/dL;
  • Cortisol = <10nM (30mins)
  • Cortisol = <10nM (60mins)
    • I.E. they are not making any cortisol in response to exogenous ACTH challenge = failure or TB
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5
Q

What are the main 3 investigation findings in Addison’s disease?

A
  1. Hyponatraemia
  2. Hyperkalaemia
  3. Low glucose
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6
Q

Case 2: What are 3 possible diagnoses?

32yo, HTN, adrenal mass

A
  • Conn’s syndrome = glomerulosa secreting aldosterone
  • Cushing’s syndrome = fasciculata tumour secreting cortisol
  • Phaeochromocytoma= medulla tumour secreting adrenaline
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7
Q

What is the test for phaeochromocytoma? What is the management?

A
  • Test = urinary catecholamines (high) – formerly known as VMA

MEDICAL EMERGENCY:

  • 1) Immediate alpha blockade* (phenoxybenzamine) - if reflex tachycardia –> move to step 2
  • 2) Add beta blockade
  • 3) Surgery
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8
Q

Name 3 genetic links for phaeochromocytoma.

A
  • MEN2 = parathyroid tumour, medullary thyroid cancer, phaeo
  • von Hippel Lindau syndrome = phaeo, renal cell carcinoma, renal cysts, haemangioblastoma
  • Neurofibromatosis type 1 = phaeo, peripheral/spinal neurofibromas, café au lait spots, etc.
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9
Q

Why is alpha blockade important in phaeochromocytoma?

A

Alpha blockade prevents death as it prevents adrenaline from binding and having its effects

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10
Q

What are the complications of MEN syndromes?

A
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11
Q

Case 3: What is the diagnosis? What is the pathogenesis?

  • 33yo, HTN
  • Urea and electrolytes:
    • Na = 147
    • K = 2.8
    • U = 4.0
    • Glucose = 4.0mM
    • Plasma aldosterone raised
    • Plasma renin suppressed
A
  • Primary hyperaldosteronism / Conn’s Syndrom
  • Adrenal gland autonomously secretes aldosterone –> HTN –> supress renin production at JGA
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12
Q

Case 4: What is the diagnosis?

  • 34yo, obese woman, T2DM, HTN, bruising
  • Urea and electrolytes:
    • Na = 146
    • K = 2.9
    • U = 4.0
    • Glucose = 14.0mM
    • Aldosterone = <75 (low)
    • Renin = low
A

Cushing’s syndrome - this excludes Conn’s as the aldosterone cannot be low

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13
Q

What are the main investigation findings in Cushing’s syndrome?

A

Low potassium

High glucose

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14
Q

What are the tests for Cushing’s?

A
  • High-dose dexamethasone suppression test (HDDST): Cushing’s tumour will not be suppressed.

LDDST at 11pm = 1mg dexamethasone and measure cortisol before 9am next day

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15
Q

Why does high cortisol cause hypertension?

A

At high concentrations, cortisol activates the MR receptors – 11b-hydroxysteroid dehydrogenase usually degrades cortisol to stop this happening but at concentration, the enzyme is overwhelmed –> HTN

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16
Q

What are the causes of Cushing’s syndrome?

A

85% Pituitary-dependant Cushing’s disease

5% Ectopic ACTH (SCLC)

10% Adrenal adenoma

17
Q

Case 5: What is the diagnosis?

A

Normal suppression - pseudo-Cushing’s sydrome due to obesity and does not need to be treated

18
Q

Case 6: What is the next step?

  • 11pm 1mg dexamethasone = 9am cortisol = 500nM

What is the diagnosis if HDDST results are as follows:

  • 9am cortisol = 500nM (HDD)
  • 9am cortisol = 170nM
A

Inferior Petrosal Sinus Sampling (IPSS)

Answer used to be HDDST - results show that it is pituitary dependent.

  • Not done anymore because 85% are pituitary-dependant without the test and doing a high-dose test is less accurate (false +ve = 20%). MRI is also not used because many people would have incidental findings (10% have <5mm tumours).
19
Q

What is Nelson’s syndrome?

A

removal of adrenal leads to pituitary enlargement (hypopituitarism by compressing stalk) and +++ ACTH (pigmentation)

20
Q

Recall the adrenal steroid synthesis.

A
21
Q

What does ACTH cause production of? What stimulates release of ACTH?

A

CRH –> ACTH –> cortisol and androgen production