CHEMPATH: Adrenal Disease Flashcards
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
- 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
Addison’s disease + primary hypothyroidism =?
-
Schmidt’s syndrome
- AKA: Polyglandular autoimmune syndrome type II
- Antibodies against the thyroid and adrenal glands
What is the test for Addison’s disease?
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
What are the main 3 investigation findings in Addison’s disease?
- Hyponatraemia
- Hyperkalaemia
- Low glucose
Case 2: What are 3 possible diagnoses?
32yo, HTN, adrenal mass
- Conn’s syndrome = glomerulosa secreting aldosterone
- Cushing’s syndrome = fasciculata tumour secreting cortisol
- Phaeochromocytoma= medulla tumour secreting adrenaline
What is the test for phaeochromocytoma? What is the management?
- 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
Name 3 genetic links for phaeochromocytoma.
- 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.
Why is alpha blockade important in phaeochromocytoma?
Alpha blockade prevents death as it prevents adrenaline from binding and having its effects
What are the complications of MEN syndromes?
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
- Primary hyperaldosteronism / Conn’s Syndrom
- Adrenal gland autonomously secretes aldosterone –> HTN –> supress renin production at JGA
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
Cushing’s syndrome - this excludes Conn’s as the aldosterone cannot be low
What are the main investigation findings in Cushing’s syndrome?
Low potassium
High glucose
What are the tests for Cushing’s?
- 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
Why does high cortisol cause hypertension?
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
What are the causes of Cushing’s syndrome?
85% Pituitary-dependant Cushing’s disease
5% Ectopic ACTH (SCLC)
10% Adrenal adenoma
Case 5: What is the diagnosis?
Normal suppression - pseudo-Cushing’s sydrome due to obesity and does not need to be treated
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
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).
What is Nelson’s syndrome?
removal of adrenal leads to pituitary enlargement (hypopituitarism by compressing stalk) and +++ ACTH (pigmentation)
Recall the adrenal steroid synthesis.
What does ACTH cause production of? What stimulates release of ACTH?
CRH –> ACTH –> cortisol and androgen production
