determine
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A 4-year-old boy is admitted for the investigation of headaches and is found to have intermittent hypertension. You suspect a neuroblastoma. Which one of the following investigations is most specific for this diagnosis?
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1) MRI or CT scan of the involved area of the body
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2) MIBG (<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Meta iodobenzylguanidine) scan
3) urinary VMA (vanylmandelic acid) and HVA (Homovane)
4) serum catecholamines<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
5) serum alpha fetoproteins
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| determine
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A 4-year-old boy is admitted for the investigation of headaches and is found to have intermittent hypertension. You suspect a neuroblastoma. Which one of the following investigations is most specific for this diagnosis?
1) MRI or CT scan of the involved area of the body
2) MIBG (<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Meta iodobenzylguanidine) scan
3) urinary VMA (vanylmandelic acid) and HVA (Homovane)
4) serum catecholamines
5) serum alpha fetoproteins
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| srf
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MIBG
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| yasmeen
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3
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| p53
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3.
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| chemamr
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which is the answer determine? could you also tell us the explanation please?
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| msyamp
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urine VMA to diagnose.
CT scan for tumour extent
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| determine
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I don`t have the answer but a friend has made a comment like this:
MIBG is a nuclear scan test that uses injected radioactive material (radioisotope) and a special scanner to locate or confirm the presence of pheochromocytoma and neuroblastoma, which are tumors of specific types of nervous tissue.
So i guess that`s right. Any other comments?
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| srf
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that is also written in step2 first aid
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| msyamp
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MIBG is positive in both pheochromocytoma and neuroblastoma. Same is urinary VMA nad HVA. more over MIBG is still not done as universally by many hospitals. I still go with VMA and HVA
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| p53
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MIBG doesn't differentiate between pheochromocytoma and neuroblastoma - urinary HVA does - it isn't elevated in pheochromocytoma but is elevated in neuroblastoma.
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| msyamp
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are you sure P 53doesnt get increased in pheochromocytoma??
I agree answer is
But i doubt VMA NOT INCREASED IN PHEOCHROMOCYTOMA
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| Reddoc
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Hi... I'd pick VMA & HVA in this case ... even though they are certainly increased in BOTH Phaeochromocytoma as well as Neuroblastoma.
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| p53
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msyamp, I haven't said that urinary VMA isn't elevated in pheochromocytoma - I said that urinary HVA isn't elevated in pheochromocytoma.
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| msyamp
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oops sorry. are you sure HVA IS NOT ELEVATED IN PHEOCHROMOCYTOMA. IT IS ELEVATED IN PHEOCHROMOCYTOMA. WHAT DO YOU SAY?
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| srf
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when I first encountered this q ,i opted for VMA. but I wrong .those who are still doing uw q bank or kaplan q bank will face this q again. at that time I made note in my first aid book which state that MIBG is a investigation of choice for detecting neuroblastoma. it detects nor epinephrine receptor.
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| msyamp
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thank youuuuuu
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| p53
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here is what exactly 'First Aid for the usmle step 2 CK 2005' says about diagnosis of pheochromocytoma, page 102:
'CT and MRI often demonstrate suprarenal mass. Screen with plasma free metanephrines (metanephrine and normetanephrine) or 24-hour urinary metanephrines. MIBG scan is SOMETIMES helpful.'
and diagnosis of neuroblastoma, page 320:
'Check abdominal CT and 24-hour urinary catecholamines for elevated VMA and HVA. Assess disease extent with CXR, bone scan, CBC, LFTs, BUN/creatinine, and coagulation panel.'
So, it's never said that MIBG is an investigation of choice for detecting neuroblastoma.
correct answer is 3.
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| msyamp
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hmm
ok thank you again so i was right first
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| p53
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furthermore, MIBG (m-iodobenzylguanidine radionuclide derivative) doesn't detect norepinephrine receptor - it's taken up by chromaffin cells and incorporated into secretory vesicles - it's particularly useful in detecting extra-adrenal metastatic lesions of pheochromocytoma.
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| determine
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thanks p53 
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| AAAAA
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Think, think, think
You are only a family doc, or internist. Do what is right, order what test?
The NBME asks you as a family doctor or general internist what can you do to the patient? Or you a med student or a first year intern !
Don't order expensive test.
There is only 1 question, 1 question in the Canadian Specialtry Examination and it is about CT scan, no MRI, no expensive test They don't ask you even as a board certified specialist to order a CT except in dissection of the aorta for CT is better than ultrasound to see the dissecting lumens
But American exam does give you all the lab and CT results, I was there, been there done that and smell that too
Any one who orders a MIBG should be fired, shot
How much is a MIBG test, who pay for it, think like a real doctor GOD
Also the VMA, a random VMA is not always elevated in pheo
have you see a real pheo?
a 3.9 VMA random result, what do you do ?
In real world, please, think in real world, random VMA is not always elevated in pheo
you can score 99% but you need real life, real world experience !
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| AAAAA
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Do the simple test, do urine VMA and HVA
In real life, do the simple tests
This is about exam taking skills, sharpen it now before it is too late
You can not know it all, and you get 45 seconds per question,
it you don't know, don't do anything if the patient is asymptomatic, fine, stbale, no complants
over 60, cancer, cancer
know the emergency stuff
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