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What Are The Tests To Identify A Pheochromocytoma?
Question: I have two questions.
1) What is the absolute best tests/scans to definitively identify a pheochromocytoma? I have completed the 24 hour urine test many times (recently and in the past). The only elevated result from the blood work was the norepinephrine (more than double normal range). At the same time, a recent MIBG-123 revealed bilateral pheochromocytoma correlating with the adrenal areas and 4 other locations (liver, spleen, kidney, salivary gland), but not a recent MRI. The results are baffling.
2) What are your impressions of these results? I plan to seek a second opinion but what are your thoughts of the results? Thanks.
1) What is the absolute best tests/scans to definitively identify a pheochromocytoma? I have completed the 24 hour urine test many times (recently and in the past). The only elevated result from the blood work was the norepinephrine (more than double normal range). At the same time, a recent MIBG-123 revealed bilateral pheochromocytoma correlating with the adrenal areas and 4 other locations (liver, spleen, kidney, salivary gland), but not a recent MRI. The results are baffling.
2) What are your impressions of these results? I plan to seek a second opinion but what are your thoughts of the results? Thanks.
Brief Answer:
Please find detailed answer below
Detailed Answer:
Hi XXXX
Thanks for writing in to us.
I find that you have got the right tests done in the workup of pheochromocytomas. The only remaining investigation is (18)F-3,4-dihydroxyphenylalanine (DOPA) positron emission tomography (PET) scanning, CT scanning, (PET/ CT). Studies suggest that scans performed with these radioisotopes are extremely useful in the detection and localization of pheochromocytomas.
Plasma metanephrine testing has the highest sensitivity (96%) for detecting a pheochromocytoma, but it has a lower specificity (85%). In comparison, a 24-hour urinary collection for catecholamines and metanephrines has a sensitivity of 87.5% and a specificity of 99.7%.
A scan with iodine-123 (123 I)–labeled metaiodobenzylguanidine (MIBG) is reserved for cases in which a pheochromocytoma is confirmed biochemically but CT scanning or MRI does not show a tumor. MIBG is a substrate for the norepinephrine transporter and concentrates within adrenal or extra-adrenal pheochromocytomas. MIBG scanning is frequently used in cases of familial pheochromocytoma syndromes, recurrent pheochromocytoma, or malignant pheochromocytoma.
Estimates of the sensitivity and specificity of123 I-MIBG vary widely. Reported sensitivity ranges from 53-94% and specificity ranges from 82-92%.
Since diagnosis of pheochromocytomas requires a lot of precision, I would go ahead with requesting you to take a second opinion and also get a PET/ CT scan if your doctor has the slightest doubt over the condition.
Hope your query is answered.
Do write back if you have any doubts.
Regards,
Dr.Vivek
Please find detailed answer below
Detailed Answer:
Hi XXXX
Thanks for writing in to us.
I find that you have got the right tests done in the workup of pheochromocytomas. The only remaining investigation is (18)F-3,4-dihydroxyphenylalanine (DOPA) positron emission tomography (PET) scanning, CT scanning, (PET/ CT). Studies suggest that scans performed with these radioisotopes are extremely useful in the detection and localization of pheochromocytomas.
Plasma metanephrine testing has the highest sensitivity (96%) for detecting a pheochromocytoma, but it has a lower specificity (85%). In comparison, a 24-hour urinary collection for catecholamines and metanephrines has a sensitivity of 87.5% and a specificity of 99.7%.
A scan with iodine-123 (123 I)–labeled metaiodobenzylguanidine (MIBG) is reserved for cases in which a pheochromocytoma is confirmed biochemically but CT scanning or MRI does not show a tumor. MIBG is a substrate for the norepinephrine transporter and concentrates within adrenal or extra-adrenal pheochromocytomas. MIBG scanning is frequently used in cases of familial pheochromocytoma syndromes, recurrent pheochromocytoma, or malignant pheochromocytoma.
Estimates of the sensitivity and specificity of123 I-MIBG vary widely. Reported sensitivity ranges from 53-94% and specificity ranges from 82-92%.
Since diagnosis of pheochromocytomas requires a lot of precision, I would go ahead with requesting you to take a second opinion and also get a PET/ CT scan if your doctor has the slightest doubt over the condition.
Hope your query is answered.
Do write back if you have any doubts.
Regards,
Dr.Vivek
Above answer was peer-reviewed by :
Dr. Vinay Bhardwaj
Answered by
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