Expert simplifies diagnosis of endocrine hypertension

ORLANDO – The diagnosis of hypertension with its origin in the endocrine system may appear complex, but it does not have to be. Primary aldosteronism may be underappreciated and underdiagnosed. On the other hand, catecholamine-secreting tumors are rare, but they often come to mind in making a diagnosis of endocrine hypertension. Dr. William Young Jr., professor of medicine at the Mayo Clinic, Rochester, Minn., presented cases in a lively session of audience participation at the annual meeting of the America Association of Clinical Endocrinologists. Later, Dr. Young summarized some of the key points in an interview, which has been edited for brevity.

Frontline Medical News: What is the endocrinologist’s role in working up the patient who has hypertension of suspected endocrine origin?

Dr. William Young Jr.: The first is knowing when to suspect endocrine hypertension. The most common form of endocrine hypertension is primary aldosteronism. So this is the adrenal-dependent autonomous production of aldosterone, which leads to high blood pressure, volume expansion, and sometimes hypokalemia. One of the concepts that many clinicians forget is that only about 30% of patients with primary aldosteronism present with hypokalemia. So 70% of patients with this disorder don’t have hypokalemia. They look like any other person with high blood pressure.

So when should we look for primary aldosteronism? Onset of high blood pressure at a young age, for example, less than age 30, drug resistant hypertension – so three drugs [with] poor control. Twenty percent of those patients will prove to have primary aldosteronism. Simply poorly controlled hypertension is another group; [or] family history of primary aldosteronism, so all first degree relatives should be tested. Or a patient who has hypertension and has had an incidental discovery of an adrenal mass should also be tested for primary aldosteronism.

Unfortunately, most primary care providers ... think that this is a complicated and dense endocrine disorder, and they frequently will not look for it, but it’s actually very simple. Some of the complexities are historical in nature in that when this disorder was first described, several rules were made for what medications a patient could be on, for example. And it’s difficult to comply with those rules. For example, if you have a patient who’s on five drugs and has poor control, you’re not going to switch him to the two drugs that are recommended because they are weak antihypertensives. It wouldn’t be ethical to do so. [The two drug classes are the calcium channel blocker verapamil and the alpha-1 antagonists doxazosin (Cardura) and terazosin (Hytrin).]

So the best thing to do regardless of what drugs the patient is on – it doesn’t matter if they’re on ACE inhibitors or angiotensin-receptor blockers or diuretics – just get a morning blood sample as your aldosterone and plasma renin activity. If aldosterone is high or generous, greater than 15 ng/dL, if the plasma renin activity is less than 1 ng/mL per hour, that’s a positive case detection test.

That doesn’t prove the patient has primary aldosteronism. The sensitivity/specificity of aldosterone and renin case detection testing is about 75%. So most patients need confirmatory testing, which would either be the saline infusion test or the 24-hour urine for aldosterone on a high-sodium diet. And once primary aldosteronism is confirmed, then we would do an adrenal-directed CT scan.

The problem with the findings in the adrenal glands on CT is that the prevalence of adrenal nodularity increases with age. So people in their 60s and 70s can have adrenal nodules that have nothing to do with aldosterone production. So whereas if the patient is less than age 35 and CT shows a unilateral macroadenoma, the contralateral adrenal is perfectly normal appearing, and the patient has a marked primary aldosteronism – so spontaneous hypokalemia, plasma aldosterone over 30 ng/dL – that subset of patients could go straight to surgery and skip adrenal vein sampling. However, everyone else over age 35 if they want to pursue the surgical option, adrenal vein sampling is a key test.

FMN: Is there anything that rules out primary aldosteronism?

Dr. Young: If the plasma aldosterone level is less than 10 ng/dL it makes primary aldosteronism very unlikely, and if the renin level is higher than 1 ng/mL per hour, that makes primary aldosteronism very unlikely.

FMN: What about working up pheochromocytoma?

Dr. Young: Clinicians, unlike with primary aldosteronism, where they don’t look for it enough, for pheochromocytoma they look for it a lot, and it’s really rare. Between 0.1 and 0.01% of the hypertensive population will prove to have pheochromocytoma.

The false positive rate with our case detection testing of plasma metanephrines about 15%. So based on how rare pheochromocytoma is and a 15% false positive rate with plasma metanephrines, 97% of patients with elevated plasma normetanephrines do not have pheochromocytoma.

So we have a real problem with case detection testing. The 24-hour urine metanephrines and catecholamines using appropriate reference ranges are probably a better way to do case detection testing for pheochromocytoma, but there’s still a false positive rate with urinary normetanephrine.

Never mistake a benign adrenal adenoma for a pheo. In terms of the imaging phenotype, pheos are dense and vascular. As they enlarge, they get cystic hemorrhagic areas within them.

FMN: What goes on with other paragangliomas?

Dr. Young: Pheochromocytoma is the term we use when you have a catecholamine-secreting tumor in the adrenal gland itself. It develops in the adrenal medulla. Paraganglioma is an identical tumor, but it’s outside of the adrenal gland. It’s somewhere in the pelvis, could be in the chest, could be in the skull base, or neck. Most commonly it’s in the abdomen. So the case detection testing is the same.

But patients we should consider testing for pheochromocytoma and paraganglioma are those with paroxysmal symptoms like episodes of pounding heartbeat, sweating, headache, tremor, and pallor. Young people with new onset hypertension, hypertension that’s poorly controlled, and vascular adrenal masses should also be tested for pheochromocytoma.

FMN: Are there things that can confound any of these tests we discussed or any drugs that should be noted that could get in the way?

Dr. Young: For pheochromocytoma, the good news is now that most reference labs use tandem mass spectrometry technology, the hypertension drugs that potentially interfered in the past like labetalol and sotalol no longer interfere. So these days the clinician doesn’t need to stop any blood pressure–related medications.

The medications that can cause false positive testing are primarily tricyclic antidepressants. Flexeril, which is cyclobenzaprine, is commonly used to treat fibromyalgia, and that is a tricyclic antidepressant, and that will cause false positive testing ... with norepinephrine and normetanephrine. Tricyclic antidepressants can increase those levels three, four, or fivefold. Levodopa, which is in Sinemet, can cause false positive testing. Antipsychotics can cause false positive testing, and MAO inhibitors ... So the clinician shouldn’t worry about blood pressure medications but should worry about the other medications the patient is taking.

FMN: When someone looks at laboratory values, should you be comparing these values to people with hypertension who do not have these conditions, and do labs have adjusted values?

Dr. Young: That’s a good question, and in the Mayo medical lab, our reference range that we use is based on patients who were tested for pheochromocytoma [and] proved not to have it. So our cutoffs are 50% to 100% higher than some other reference labs.

These other reference labs use normal laboratory volunteers who have normal blood pressure and who are taking no medications, and I’ve never tested such a patient for pheochromocytoma, so why would we use that group of people to determine our reference range? So we should use reference ranges based on patients tested for pheo but who prove to not have pheo. And that leads to higher accuracy of our case detection tests.

FMN: What are the treatments for these conditions and follow-up? I take it if there’s an adrenal mass, you get a surgeon, and I think you also noted that you need an experienced endocrine surgeon.

Dr. Young: For primary aldosteronism, if the patient has a unilateral aldosterone-producing adenoma, the outstanding treatment is laparoscopic adrenalectomy. Patients are in the hospital one night, [and] they’re back at work in 7-10 days, but that does require an expert laparoscopic adrenal surgeon. And in the United States we have a 1-year endocrine surgery program. It’s optimal that patients are referred to surgeons who have done that unique training.

For pheochromocytoma less than 8-9 cm, laparoscopic adrenalectomy with an experienced endocrine surgeon is an excellent treatment option. When the adrenal pheochromocytoma is larger than 8 or 9 cm, especially if it’s cystic, the surgeon may want to do it as open [surgery] because it’s critical that the capsule of the pheochromocytoma is not ruptured intraoperatively. If it is ruptured, a benign pheochromocytoma has just been transformed to malignant, incurable disease.

If it’s a paraganglioma, typically that requires an open operation whether it’s in the neck or the chest or the pelvis or lower abdomen.

FMN: What is the follow-up to any of these conditions?

Dr. Young: The follow-up once you’ve resected an adrenal pheochromocytoma depends on whether there is a germline mutation. If there is a germline mutation, for example, succinate dehydrogenase mutation [SDH], these patients are at higher risk for developing recurrent pheochromocytoma or paraganglioma, and they’re at risk for developing malignant pheochromocytoma or paraganglioma.

One of our challenges is when we resect a pheochromocytoma or paraganglioma, the pathologist doesn’t have the tools to tell us if it’s benign or malignant ... So all patients need lifelong biochemical follow-up, basically a 24-hour urine for metanephrines and catecholamines annually or plasma metanephrines for life.

If the patients have an underlying mutation like succinate dehydrogenase, they’re at risk for developing nonfunctioning paragangliomas. So these patients need periodic imaging in addition to the annual biochemical testing. For example, if a patient had an abdominal paraganglioma with an SDHB [succinate dehydrogenase complex iron sulfur subunit B], we would do abdominal MRI scans every 1-2 years. That would include the pelvis. We would screen for paragangliomas elsewhere with MRI of the skull base and neck and the chest every 3-5 years, and a total body scan every 5 years or so, either FDG-PET [¹⁸F-fluorodeoxyglucose positron emission tomography] scan or ¹²³I-MIBG [metaiodobenzyl-guanidine] scan.

FMN: Is there anything that is particularly new in the past couple of years?

Dr. Young: Some of the innovations lately have been in the area of metastatic pheochromocytoma and paraganglioma. These are in patients who have limited metastatic disease that’s localized to bone or to liver, and we’ve been using ablative therapies. This includes cryoablation ... and radiofrequency ablation, which is killing the tumor with hot temperature, and that’s very effective for patients who have limited metastatic lesions in the bone or liver.

For patients with complex tumors in difficult areas of the body, for example, in the mediastinum or surrounding the heart, we’ve been using 3D printer technology to print [a replica of the structures and] the tumor preoperatively, and this assists in surgical planning.

FMN: And what do you see coming?

Dr. Young: I think we’re getting close to something near curative for patients with malignant pheochromocytoma and paraganglioma. We’re understanding the basic biology better [and] pathophysiology, and I think that’s going to lead to some novel treatments.

Also, what I see coming is that we’ll be able to use germline mutation information and somatic tumor mutation information to guide us on specific imaging modalities, to guide us on forms of preventative therapy so that we prevent the paraganglioma from ever developing and also provide us with additional treatment options.

ORLANDO – The diagnosis of hypertension with its origin in the endocrine system may appear complex, but it does not have to be. Primary aldosteronism may be underappreciated and underdiagnosed. On the other hand, catecholamine-secreting tumors are rare, but they often come to mind in making a diagnosis of endocrine hypertension. Dr. William Young Jr., professor of medicine at the Mayo Clinic, Rochester, Minn., presented cases in a lively session of audience participation at the annual meeting of the America Association of Clinical Endocrinologists. Later, Dr. Young summarized some of the key points in an interview, which has been edited for brevity.

Frontline Medical News: What is the endocrinologist’s role in working up the patient who has hypertension of suspected endocrine origin?

Dr. William Young Jr.: The first is knowing when to suspect endocrine hypertension. The most common form of endocrine hypertension is primary aldosteronism. So this is the adrenal-dependent autonomous production of aldosterone, which leads to high blood pressure, volume expansion, and sometimes hypokalemia. One of the concepts that many clinicians forget is that only about 30% of patients with primary aldosteronism present with hypokalemia. So 70% of patients with this disorder don’t have hypokalemia. They look like any other person with high blood pressure.

So when should we look for primary aldosteronism? Onset of high blood pressure at a young age, for example, less than age 30, drug resistant hypertension – so three drugs [with] poor control. Twenty percent of those patients will prove to have primary aldosteronism. Simply poorly controlled hypertension is another group; [or] family history of primary aldosteronism, so all first degree relatives should be tested. Or a patient who has hypertension and has had an incidental discovery of an adrenal mass should also be tested for primary aldosteronism.

Unfortunately, most primary care providers ... think that this is a complicated and dense endocrine disorder, and they frequently will not look for it, but it’s actually very simple. Some of the complexities are historical in nature in that when this disorder was first described, several rules were made for what medications a patient could be on, for example. And it’s difficult to comply with those rules. For example, if you have a patient who’s on five drugs and has poor control, you’re not going to switch him to the two drugs that are recommended because they are weak antihypertensives. It wouldn’t be ethical to do so. [The two drug classes are the calcium channel blocker verapamil and the alpha-1 antagonists doxazosin (Cardura) and terazosin (Hytrin).]

So the best thing to do regardless of what drugs the patient is on – it doesn’t matter if they’re on ACE inhibitors or angiotensin-receptor blockers or diuretics – just get a morning blood sample as your aldosterone and plasma renin activity. If aldosterone is high or generous, greater than 15 ng/dL, if the plasma renin activity is less than 1 ng/mL per hour, that’s a positive case detection test.

That doesn’t prove the patient has primary aldosteronism. The sensitivity/specificity of aldosterone and renin case detection testing is about 75%. So most patients need confirmatory testing, which would either be the saline infusion test or the 24-hour urine for aldosterone on a high-sodium diet. And once primary aldosteronism is confirmed, then we would do an adrenal-directed CT scan.

The problem with the findings in the adrenal glands on CT is that the prevalence of adrenal nodularity increases with age. So people in their 60s and 70s can have adrenal nodules that have nothing to do with aldosterone production. So whereas if the patient is less than age 35 and CT shows a unilateral macroadenoma, the contralateral adrenal is perfectly normal appearing, and the patient has a marked primary aldosteronism – so spontaneous hypokalemia, plasma aldosterone over 30 ng/dL – that subset of patients could go straight to surgery and skip adrenal vein sampling. However, everyone else over age 35 if they want to pursue the surgical option, adrenal vein sampling is a key test.

FMN: Is there anything that rules out primary aldosteronism?

Dr. Young: If the plasma aldosterone level is less than 10 ng/dL it makes primary aldosteronism very unlikely, and if the renin level is higher than 1 ng/mL per hour, that makes primary aldosteronism very unlikely.

FMN: What about working up pheochromocytoma?

Dr. Young: Clinicians, unlike with primary aldosteronism, where they don’t look for it enough, for pheochromocytoma they look for it a lot, and it’s really rare. Between 0.1 and 0.01% of the hypertensive population will prove to have pheochromocytoma.

The false positive rate with our case detection testing of plasma metanephrines about 15%. So based on how rare pheochromocytoma is and a 15% false positive rate with plasma metanephrines, 97% of patients with elevated plasma normetanephrines do not have pheochromocytoma.

So we have a real problem with case detection testing. The 24-hour urine metanephrines and catecholamines using appropriate reference ranges are probably a better way to do case detection testing for pheochromocytoma, but there’s still a false positive rate with urinary normetanephrine.

Never mistake a benign adrenal adenoma for a pheo. In terms of the imaging phenotype, pheos are dense and vascular. As they enlarge, they get cystic hemorrhagic areas within them.

FMN: What goes on with other paragangliomas?

Dr. Young: Pheochromocytoma is the term we use when you have a catecholamine-secreting tumor in the adrenal gland itself. It develops in the adrenal medulla. Paraganglioma is an identical tumor, but it’s outside of the adrenal gland. It’s somewhere in the pelvis, could be in the chest, could be in the skull base, or neck. Most commonly it’s in the abdomen. So the case detection testing is the same.

But patients we should consider testing for pheochromocytoma and paraganglioma are those with paroxysmal symptoms like episodes of pounding heartbeat, sweating, headache, tremor, and pallor. Young people with new onset hypertension, hypertension that’s poorly controlled, and vascular adrenal masses should also be tested for pheochromocytoma.

FMN: Are there things that can confound any of these tests we discussed or any drugs that should be noted that could get in the way?

Dr. Young: For pheochromocytoma, the good news is now that most reference labs use tandem mass spectrometry technology, the hypertension drugs that potentially interfered in the past like labetalol and sotalol no longer interfere. So these days the clinician doesn’t need to stop any blood pressure–related medications.

The medications that can cause false positive testing are primarily tricyclic antidepressants. Flexeril, which is cyclobenzaprine, is commonly used to treat fibromyalgia, and that is a tricyclic antidepressant, and that will cause false positive testing ... with norepinephrine and normetanephrine. Tricyclic antidepressants can increase those levels three, four, or fivefold. Levodopa, which is in Sinemet, can cause false positive testing. Antipsychotics can cause false positive testing, and MAO inhibitors ... So the clinician shouldn’t worry about blood pressure medications but should worry about the other medications the patient is taking.

FMN: When someone looks at laboratory values, should you be comparing these values to people with hypertension who do not have these conditions, and do labs have adjusted values?

Dr. Young: That’s a good question, and in the Mayo medical lab, our reference range that we use is based on patients who were tested for pheochromocytoma [and] proved not to have it. So our cutoffs are 50% to 100% higher than some other reference labs.

These other reference labs use normal laboratory volunteers who have normal blood pressure and who are taking no medications, and I’ve never tested such a patient for pheochromocytoma, so why would we use that group of people to determine our reference range? So we should use reference ranges based on patients tested for pheo but who prove to not have pheo. And that leads to higher accuracy of our case detection tests.

FMN: What are the treatments for these conditions and follow-up? I take it if there’s an adrenal mass, you get a surgeon, and I think you also noted that you need an experienced endocrine surgeon.

Dr. Young: For primary aldosteronism, if the patient has a unilateral aldosterone-producing adenoma, the outstanding treatment is laparoscopic adrenalectomy. Patients are in the hospital one night, [and] they’re back at work in 7-10 days, but that does require an expert laparoscopic adrenal surgeon. And in the United States we have a 1-year endocrine surgery program. It’s optimal that patients are referred to surgeons who have done that unique training.

For pheochromocytoma less than 8-9 cm, laparoscopic adrenalectomy with an experienced endocrine surgeon is an excellent treatment option. When the adrenal pheochromocytoma is larger than 8 or 9 cm, especially if it’s cystic, the surgeon may want to do it as open [surgery] because it’s critical that the capsule of the pheochromocytoma is not ruptured intraoperatively. If it is ruptured, a benign pheochromocytoma has just been transformed to malignant, incurable disease.

If it’s a paraganglioma, typically that requires an open operation whether it’s in the neck or the chest or the pelvis or lower abdomen.

FMN: What is the follow-up to any of these conditions?

Dr. Young: The follow-up once you’ve resected an adrenal pheochromocytoma depends on whether there is a germline mutation. If there is a germline mutation, for example, succinate dehydrogenase mutation [SDH], these patients are at higher risk for developing recurrent pheochromocytoma or paraganglioma, and they’re at risk for developing malignant pheochromocytoma or paraganglioma.

One of our challenges is when we resect a pheochromocytoma or paraganglioma, the pathologist doesn’t have the tools to tell us if it’s benign or malignant ... So all patients need lifelong biochemical follow-up, basically a 24-hour urine for metanephrines and catecholamines annually or plasma metanephrines for life.

If the patients have an underlying mutation like succinate dehydrogenase, they’re at risk for developing nonfunctioning paragangliomas. So these patients need periodic imaging in addition to the annual biochemical testing. For example, if a patient had an abdominal paraganglioma with an SDHB [succinate dehydrogenase complex iron sulfur subunit B], we would do abdominal MRI scans every 1-2 years. That would include the pelvis. We would screen for paragangliomas elsewhere with MRI of the skull base and neck and the chest every 3-5 years, and a total body scan every 5 years or so, either FDG-PET [¹⁸F-fluorodeoxyglucose positron emission tomography] scan or ¹²³I-MIBG [metaiodobenzyl-guanidine] scan.

FMN: Is there anything that is particularly new in the past couple of years?

Dr. Young: Some of the innovations lately have been in the area of metastatic pheochromocytoma and paraganglioma. These are in patients who have limited metastatic disease that’s localized to bone or to liver, and we’ve been using ablative therapies. This includes cryoablation ... and radiofrequency ablation, which is killing the tumor with hot temperature, and that’s very effective for patients who have limited metastatic lesions in the bone or liver.

For patients with complex tumors in difficult areas of the body, for example, in the mediastinum or surrounding the heart, we’ve been using 3D printer technology to print [a replica of the structures and] the tumor preoperatively, and this assists in surgical planning.

FMN: And what do you see coming?

Dr. Young: I think we’re getting close to something near curative for patients with malignant pheochromocytoma and paraganglioma. We’re understanding the basic biology better [and] pathophysiology, and I think that’s going to lead to some novel treatments.

Also, what I see coming is that we’ll be able to use germline mutation information and somatic tumor mutation information to guide us on specific imaging modalities, to guide us on forms of preventative therapy so that we prevent the paraganglioma from ever developing and also provide us with additional treatment options.

ORLANDO – The diagnosis of hypertension with its origin in the endocrine system may appear complex, but it does not have to be. Primary aldosteronism may be underappreciated and underdiagnosed. On the other hand, catecholamine-secreting tumors are rare, but they often come to mind in making a diagnosis of endocrine hypertension. Dr. William Young Jr., professor of medicine at the Mayo Clinic, Rochester, Minn., presented cases in a lively session of audience participation at the annual meeting of the America Association of Clinical Endocrinologists. Later, Dr. Young summarized some of the key points in an interview, which has been edited for brevity.

Frontline Medical News: What is the endocrinologist’s role in working up the patient who has hypertension of suspected endocrine origin?

Dr. William Young Jr.: The first is knowing when to suspect endocrine hypertension. The most common form of endocrine hypertension is primary aldosteronism. So this is the adrenal-dependent autonomous production of aldosterone, which leads to high blood pressure, volume expansion, and sometimes hypokalemia. One of the concepts that many clinicians forget is that only about 30% of patients with primary aldosteronism present with hypokalemia. So 70% of patients with this disorder don’t have hypokalemia. They look like any other person with high blood pressure.

So when should we look for primary aldosteronism? Onset of high blood pressure at a young age, for example, less than age 30, drug resistant hypertension – so three drugs [with] poor control. Twenty percent of those patients will prove to have primary aldosteronism. Simply poorly controlled hypertension is another group; [or] family history of primary aldosteronism, so all first degree relatives should be tested. Or a patient who has hypertension and has had an incidental discovery of an adrenal mass should also be tested for primary aldosteronism.

Unfortunately, most primary care providers ... think that this is a complicated and dense endocrine disorder, and they frequently will not look for it, but it’s actually very simple. Some of the complexities are historical in nature in that when this disorder was first described, several rules were made for what medications a patient could be on, for example. And it’s difficult to comply with those rules. For example, if you have a patient who’s on five drugs and has poor control, you’re not going to switch him to the two drugs that are recommended because they are weak antihypertensives. It wouldn’t be ethical to do so. [The two drug classes are the calcium channel blocker verapamil and the alpha-1 antagonists doxazosin (Cardura) and terazosin (Hytrin).]

So the best thing to do regardless of what drugs the patient is on – it doesn’t matter if they’re on ACE inhibitors or angiotensin-receptor blockers or diuretics – just get a morning blood sample as your aldosterone and plasma renin activity. If aldosterone is high or generous, greater than 15 ng/dL, if the plasma renin activity is less than 1 ng/mL per hour, that’s a positive case detection test.

That doesn’t prove the patient has primary aldosteronism. The sensitivity/specificity of aldosterone and renin case detection testing is about 75%. So most patients need confirmatory testing, which would either be the saline infusion test or the 24-hour urine for aldosterone on a high-sodium diet. And once primary aldosteronism is confirmed, then we would do an adrenal-directed CT scan.

The problem with the findings in the adrenal glands on CT is that the prevalence of adrenal nodularity increases with age. So people in their 60s and 70s can have adrenal nodules that have nothing to do with aldosterone production. So whereas if the patient is less than age 35 and CT shows a unilateral macroadenoma, the contralateral adrenal is perfectly normal appearing, and the patient has a marked primary aldosteronism – so spontaneous hypokalemia, plasma aldosterone over 30 ng/dL – that subset of patients could go straight to surgery and skip adrenal vein sampling. However, everyone else over age 35 if they want to pursue the surgical option, adrenal vein sampling is a key test.

FMN: Is there anything that rules out primary aldosteronism?

Dr. Young: If the plasma aldosterone level is less than 10 ng/dL it makes primary aldosteronism very unlikely, and if the renin level is higher than 1 ng/mL per hour, that makes primary aldosteronism very unlikely.

FMN: What about working up pheochromocytoma?

Dr. Young: Clinicians, unlike with primary aldosteronism, where they don’t look for it enough, for pheochromocytoma they look for it a lot, and it’s really rare. Between 0.1 and 0.01% of the hypertensive population will prove to have pheochromocytoma.

The false positive rate with our case detection testing of plasma metanephrines about 15%. So based on how rare pheochromocytoma is and a 15% false positive rate with plasma metanephrines, 97% of patients with elevated plasma normetanephrines do not have pheochromocytoma.

So we have a real problem with case detection testing. The 24-hour urine metanephrines and catecholamines using appropriate reference ranges are probably a better way to do case detection testing for pheochromocytoma, but there’s still a false positive rate with urinary normetanephrine.

Never mistake a benign adrenal adenoma for a pheo. In terms of the imaging phenotype, pheos are dense and vascular. As they enlarge, they get cystic hemorrhagic areas within them.

FMN: What goes on with other paragangliomas?

Dr. Young: Pheochromocytoma is the term we use when you have a catecholamine-secreting tumor in the adrenal gland itself. It develops in the adrenal medulla. Paraganglioma is an identical tumor, but it’s outside of the adrenal gland. It’s somewhere in the pelvis, could be in the chest, could be in the skull base, or neck. Most commonly it’s in the abdomen. So the case detection testing is the same.

But patients we should consider testing for pheochromocytoma and paraganglioma are those with paroxysmal symptoms like episodes of pounding heartbeat, sweating, headache, tremor, and pallor. Young people with new onset hypertension, hypertension that’s poorly controlled, and vascular adrenal masses should also be tested for pheochromocytoma.

FMN: Are there things that can confound any of these tests we discussed or any drugs that should be noted that could get in the way?

Dr. Young: For pheochromocytoma, the good news is now that most reference labs use tandem mass spectrometry technology, the hypertension drugs that potentially interfered in the past like labetalol and sotalol no longer interfere. So these days the clinician doesn’t need to stop any blood pressure–related medications.

The medications that can cause false positive testing are primarily tricyclic antidepressants. Flexeril, which is cyclobenzaprine, is commonly used to treat fibromyalgia, and that is a tricyclic antidepressant, and that will cause false positive testing ... with norepinephrine and normetanephrine. Tricyclic antidepressants can increase those levels three, four, or fivefold. Levodopa, which is in Sinemet, can cause false positive testing. Antipsychotics can cause false positive testing, and MAO inhibitors ... So the clinician shouldn’t worry about blood pressure medications but should worry about the other medications the patient is taking.

FMN: When someone looks at laboratory values, should you be comparing these values to people with hypertension who do not have these conditions, and do labs have adjusted values?

Dr. Young: That’s a good question, and in the Mayo medical lab, our reference range that we use is based on patients who were tested for pheochromocytoma [and] proved not to have it. So our cutoffs are 50% to 100% higher than some other reference labs.

These other reference labs use normal laboratory volunteers who have normal blood pressure and who are taking no medications, and I’ve never tested such a patient for pheochromocytoma, so why would we use that group of people to determine our reference range? So we should use reference ranges based on patients tested for pheo but who prove to not have pheo. And that leads to higher accuracy of our case detection tests.

FMN: What are the treatments for these conditions and follow-up? I take it if there’s an adrenal mass, you get a surgeon, and I think you also noted that you need an experienced endocrine surgeon.

Dr. Young: For primary aldosteronism, if the patient has a unilateral aldosterone-producing adenoma, the outstanding treatment is laparoscopic adrenalectomy. Patients are in the hospital one night, [and] they’re back at work in 7-10 days, but that does require an expert laparoscopic adrenal surgeon. And in the United States we have a 1-year endocrine surgery program. It’s optimal that patients are referred to surgeons who have done that unique training.

For pheochromocytoma less than 8-9 cm, laparoscopic adrenalectomy with an experienced endocrine surgeon is an excellent treatment option. When the adrenal pheochromocytoma is larger than 8 or 9 cm, especially if it’s cystic, the surgeon may want to do it as open [surgery] because it’s critical that the capsule of the pheochromocytoma is not ruptured intraoperatively. If it is ruptured, a benign pheochromocytoma has just been transformed to malignant, incurable disease.

If it’s a paraganglioma, typically that requires an open operation whether it’s in the neck or the chest or the pelvis or lower abdomen.

FMN: What is the follow-up to any of these conditions?

Dr. Young: The follow-up once you’ve resected an adrenal pheochromocytoma depends on whether there is a germline mutation. If there is a germline mutation, for example, succinate dehydrogenase mutation [SDH], these patients are at higher risk for developing recurrent pheochromocytoma or paraganglioma, and they’re at risk for developing malignant pheochromocytoma or paraganglioma.

One of our challenges is when we resect a pheochromocytoma or paraganglioma, the pathologist doesn’t have the tools to tell us if it’s benign or malignant ... So all patients need lifelong biochemical follow-up, basically a 24-hour urine for metanephrines and catecholamines annually or plasma metanephrines for life.

If the patients have an underlying mutation like succinate dehydrogenase, they’re at risk for developing nonfunctioning paragangliomas. So these patients need periodic imaging in addition to the annual biochemical testing. For example, if a patient had an abdominal paraganglioma with an SDHB [succinate dehydrogenase complex iron sulfur subunit B], we would do abdominal MRI scans every 1-2 years. That would include the pelvis. We would screen for paragangliomas elsewhere with MRI of the skull base and neck and the chest every 3-5 years, and a total body scan every 5 years or so, either FDG-PET [¹⁸F-fluorodeoxyglucose positron emission tomography] scan or ¹²³I-MIBG [metaiodobenzyl-guanidine] scan.

FMN: Is there anything that is particularly new in the past couple of years?

Dr. Young: Some of the innovations lately have been in the area of metastatic pheochromocytoma and paraganglioma. These are in patients who have limited metastatic disease that’s localized to bone or to liver, and we’ve been using ablative therapies. This includes cryoablation ... and radiofrequency ablation, which is killing the tumor with hot temperature, and that’s very effective for patients who have limited metastatic lesions in the bone or liver.

For patients with complex tumors in difficult areas of the body, for example, in the mediastinum or surrounding the heart, we’ve been using 3D printer technology to print [a replica of the structures and] the tumor preoperatively, and this assists in surgical planning.

FMN: And what do you see coming?

Dr. Young: I think we’re getting close to something near curative for patients with malignant pheochromocytoma and paraganglioma. We’re understanding the basic biology better [and] pathophysiology, and I think that’s going to lead to some novel treatments.

Also, what I see coming is that we’ll be able to use germline mutation information and somatic tumor mutation information to guide us on specific imaging modalities, to guide us on forms of preventative therapy so that we prevent the paraganglioma from ever developing and also provide us with additional treatment options.