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Medicine

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Endocrine

Question
9 out of 11
 

Which of the following is the most sensitive test to diagnose Pheochromocytoma? (NEET 2013)



A Urinary total metanephrine

B Urinary VMA measurements

C Urinary catecholamines

D Abdominal CT scan

Ans. A

Urinary total metanephrine

Diagnosis of pheochromocytoma :

1). Screening test: phentolamine test (MCQ):

2). The diagnosis of pheochromocytoma is established by the demonstration of increased production of catecholamine or catecholamine metabolites (VMA or the metanephrine).

3). The diagnosis can usually be made by analysis of a single 24 h urine sample.

a. Urinary total metanephrine: Most sensitive and specific screening test for pheochromocytoma

b. Urinary VMA measurements: Less sensitive and specific than urinary metanephrine measurements.

c. Urinary catecholamines

d. Localization: Abdominal CT/MRI, or meta-iodobenzylguanidine (MIBG-Chromaffin-seeking isotope) scan: 111In somatostatin analogue or 18F-dopa PET scan useful for detection of extra-adrenal tumours.

Table - Biochemical and Imaging Methods Used for Pheochromocytoma and Paraganglioma Diagnosis

(Ref. Hari-18th ed., Pg 2963, Table 343.2)

Diagnostic Method

Sensitivity

Specificity

1). 24-h urinary tests

a. Vanillylmandelic acid

++

++++

b. Catecholamines

+++

+++

c. Fractionated metanephrine

++++

++

d. Total metanephrine

+++

++++

2). Plasma tests

a. Catecholamines

+++

++

b. Free metanephrine

++++

+++

c. Chromogranin A

+++

++

3). CT

++++

+++

4). MRI

++++

+++

5). MIBG scintigraphy

+++

++++

6). Somatostatin receptor scintigraphy

++

++

7). Dopa (dopamine) PET (preliminary data)

++++

++++

Extra Edge: For localization of tumour, contrast CT/MRI and MIBG scintigraphy is used

Endocrine Flashcard List

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