Phaeochromocytoma

Question 1

a) What is phaeochromocytoma?
b) How does it differ from
neuroblastoma

Answer 1

a) tumours of chromaffin tissue 90% in adrenal medulla (neuroendocrine gland) = catechollamine secreting (nor&adrenaline). *Sporadic (40% familial/inherited)
b) Tumours of nerve cells external to medulla & happen in adolescence. = nonsympathetic. Sporadic
BOTH: sporadic

Question 2

What analytes are used for diagnosis of Phaechromocytoma

Answer 2

Measure catecholamine and metabolites
- 24hr urine catecholamine
- plasma catecholamine
- 24hr Urine metanephrine
- plasma metanephrine
- 24hr urine HMMA (product of VMA)

Question 3

What are the clinical features of phaeochromocytoma (relate it to the physiological effects of excess catecholamine secretion)

Answer 3

(excess secretion of catecholamine)
Present classic triad (though not always)
* Hypertension (Hi BP)
* Headaches (Blood supply to brain)
* Sweating (Glu to muscles=active)
- Anxiety/fear
- Palpitations/nausea
- Vomiting

Question 4

How are catecholamines measured?

Answer 4

• competitive or titrimetric Immunoassays bc
• HPLC or MS (urine nor/adrenaline)
• Tandem MS/MS

Question 5

For diagnosis of neuroblastoma What is being measured in biochemical tests>

Answer 5

• Excess dopamine secretion
• Measure Vanillylmandelic acid (VMA) & Homovanillic acid (HVA)
• allcatecholamine except adrenaline & metabolites
• dopamine metabolites

Question 6

the physiological effects of adrenaline secretion?

Answer 6

• Mobilises body fuels via B receptors: Glycogenolysis in liver & Sk.Mu & lypolysis => Glu & Tg-> FFA
• Cardiovascular effects: Inc <3 output & PB mainly to brain & Sk.Mu
• Increased alertness
  *NOTE: effects mediated by a & B adrenergenic receptors

Question 7

What pre-analytical factors influence catecholamines concentration?

Answer 7

Physiological factors
- Excercise
- Hypoglycemia
- Pain
- stress
Drugs
- antihypertensive drugs
- a & B adrenergic blockers
Foods e.g. dietary catechols influence urinary catecholamine lvls

Question 8

Why might urine lvl measurement be useful than plasma lvls? But what might be the complications of urinary measurement?

Answer 8

a) urine more useful bc better representation unlike the episodic nature of plasma (lower Sp)
b) need to collect 24hr urine: pt may forget to collect, bladder not empty completely

Question 9

T/F: cond. below can result in hyperglycemia
- Phaechromocytoma
- Cushing’s syndrome
- Growth hormone

Answer 9

T