The Adrenal Gland Lecture Flashcards
1
Q
Anatomy of adrenal gland
A
- 4-5g
- 90% is cortex surrounding medulla
- Arterial supply from renal arteries, aorta and inferior phrenic artery
- Venous drainaing right –> IVC, left –> left renal vein
Venous drainage important to note for sampling
2
Q
3 zones of cortex
A
- Zona glomerulosa
- Zona fasiculata
- Zona reticularis
GFR
3
Q
What does each zone produce?
A
- G - mineralocorticoids (salt) Aldosterone under RAAS control
- F - glucocorticoids (sugar) cortisol under ACTH control
- R - androgens (sex) DHEA and andronstenedione under ACTH control
4
Q
Significance of aldosterone not being under ACTH control
A
If have pituitary problem, aldosterone will not need to be replaced as won’t be affected
5
Q
Normal amount of aldosterone and cortisol and DHEA daily
A
- Aldosterone 100-150mcg/day
- Cortisol - 10-20mg/day
- DHEA - 10mg/day
6
Q
Causes of mineralocorticoid deficiency
A
- Congenital eg congenital adrenal hyperplasia 21-hydroxylase deficiency
Acquired:
* primary adrenal insuffiency,
* secondary due to low renin in renal tubular acidosis (diabetes)
* Drug induced eg heparin, ciclosporin
7
Q
Treatment for mineralocorticoid deficiency
A
Fludrocortisone 50-100mcg / day
8
Q
Cautions with fludrocortisone
A
- Can cause fluid overload - HF caution
- Can cause hypokalaemia
9
Q
Adrenal insufficiency causes
A
- Addisons
- Congenital adrenal hyperplasia
- Secondary - hypothalamic or pituitary dysfunction
10
Q
Causes of primary adrenal insufficiency - acquired
A
- Autoimmune
- Malignancy (mets or lymphoma)
- Infiltration - sarcoidosis, amyloidosis
- Infection - TB, fungal, HIV
- Vascular - haemorrhage, meningococcal septicaemia
- Infarction - thrombosis
11
Q
Causes of congenital primary AI
A
- CAH
- CLAH
- Triple A syndrome
- X linked adrenal leukodystrophy
12
Q
Causes of primary AI iatrogenic
A
- Bilateral adrenalectomy
- Drugs - etomidate, ketoconazole, mitotane
13
Q
Causes of secondary AI - more common than primary
A
- Tumours
- Infection
- Infiltation
- Isolated ACTH deficiency
- Exogenous steroid use suppressing axis
14
Q
Clinical features of AI - primary
A
- Anorexia
- Weight loss
- Tiredness
- Weakness
- Hyperpigmentation
- Dizziness and postural hypotension
- N+V
- Abdo pain
- Arthralgia
- Myalgia
- Reduced libido and pubic hair
- Salt craving
15
Q
Secondary AI clinical features
A
- Same as primary
- BUT no hyperpigmentation as there is no increased ACTH to cause this - no mineralocorticoid deficiency
- Low ACTH is the problem in secondary remember
16
Q
Investigation for AI - findings
A
- Hyponatraemia
- Hyperkalaemia
- Elevated urea
- Anaemia
- Eosinophilia
- Hypercalcaemia (mild)
- Hypoglycaemia
17
Q
Investigations for AI
A
- 9am cortisol (should be peak)
- ACTH
- TFTs
- Short synacthen test
- Renin - increased in primary
- Adrenal antibodies
- CT scan +/- biopsy?
18
Q
What is SST?
A
- 9am cortisol bloods
- Administer ACTH
- Do bloods 30mins and 60 mins after
- Cortisol should double
19
Q
Treatment for AI
A
- Glucocorticoid - hydrocortisone BD/TDS
- Mineralocorticoid - Fludrocortisone
- DHEA replacement? - not usually needed
20
Q
Advice for someone on replacement for AI
A
- Sick day rules - double steroid dose
- Steroid card
- Emergency pack -has IM hydrocortisone if adrenal crisis, go to hospital if inject
21
Q
Management of adrenal crisis
A
- O2
- IV access
- Fluids 0.9% NaCl
- Dextrose in cases of hypoglycaemia
- Hydrocortisone IV 100mg bolus then every 6hrs for 24-48hrs (then titrated down)
- Fludrocortisone when HC dose less than 50mg
Be mindful of chronic hypoNa - no more than 10-15mmol/L in 24hrs
22
Q
Presentation of adrenal crisis
A
- Hyponatraemia
- Hyperkalaemia
- Hypoglycaemia
- Shock
23
Q
When to investigate for secondary causes of HTN?
A
- If less than 40
- Resistant to medication
- Hypokalaemia
24
Q
Causes of mineralocorticoid excess
A
- Primary aldosteronism (Conns - adenoma, bilateral hyperplasia, GRA)
-
- Secondary - RTA, renovascular, cirrhosis, CHF, nephrotic syndrome, renin secreting tumour (all increases renin)
Other:
* Liqourice
* Ectopic ACTH
* Exogenous
25
Most common cause primary hyperaldosteronism
Bilateral hyperplasia
26
What is GRA?
Glucocorticoid-remediable Aldosteronism
When ACTH activates aldosterone instead of RAAS
27
Presentation of hyperaldosteronism
* Under 40
* Resistant hypertension
* Hypokalaemia
28
Investigations for hyperaldosteronism
* Aldosterone renin ratio
* Saline infusion - usually suppresses
* Fludrocortisone suppression
* Captopril supression
* Genetic testing if GRA
* Localise - CT/MRI, adrenal venous sampling, radiolabelled sampling
29
Things that can effect aldosterone renin ratio
* Beta blockers can cause false +ve
* ACEi can cause false -ve
* Spironolactone needs to be stopped 4-6 weeks prior test
30
Treatment primary hyperaldosteronism
* Surgery - laparascopic adrenalectomy
* Medical - mineralocorticoid receptor antagonists eg spironolactone, eplerenone
31
GRA management
* Low dose dexamethasone - suppress the ACTH
32
Causes of Cushings syndrome ACTH independent
* Adrenal adenoma
* Adrenal carcinoma
* Bilateral micro/macronodular hyperplasia
33
Associated features of Cushings syndrome - systemic
* HTN
* DM
* Osteoporosis
* Recurrent infections
34
Investigations for Cushings syndrome
* 24hr urine free cortisol - x2
* Overnight dexamethasone suppression test
* Salivary cortisol
* Midnight cortisol
* Low dose DMT or HDDT
* ACTH, serum K, CRH
* CT adrenal if points to this
| Step1 - find raised cortisol, step 2 check ACTH, step 3 adrenals
35
Treatment for Cushings syndrome adrenal
* Adenoma - unilateral adrenalectomy
* Carcinoma - surgery, chemo, adrenolytic agents
* Bilateral hyperplasia - bilateral adrenalectomy
36
What is phaechromocytoma?
* Tumour arising from adrenal medulla
* 10% bilateral, 10% FH, 10% malignant
37
When to screen for phaechromocytoma?
* Young pts with HTN
* Adrenal incidentaloma
* Unexplained HF
* Hypertensive crisis during general anaesthesia
38
Gene mutations associated with phaechromocytoma
* Multiple endocrine neoplasia (MEN)
* VHL - Von Hippel Lindau
* NF - neurofibromatosis
* SDH - tumour supressor mutation
* MAX
* TMEM
39
Investigation for phaechromocytoma
* 24hr urine catacholamines/metanephrines
* Plasma metanephrines (more sensitive, less specific)
* Localise - CT, MRI, MIBG, FDG PET
40
Management of phaechromocytoma
* Alpha blockade (FIRST) eg Phenoxybenzamine
* Beta blockage
* Monitor BP, haematocrit and fluid status
* Surgical resection when stable
41
Management of phaechromocytoma crisis
* ICU admission
* Ventilation may be needed due to extreme hypoxia
* Alpha blockade with phenoxybenzamine and prazosin
* Correct IV volume - IV fluids and high salt
* Beta blockade after adequate alpha
* Surgical removal
42
Why alpha blockade before beta?
Avoid unapposed alpha adrenergic activity
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