Pheochromocytoma laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2] Mohammed Abdelwahed M.D[3]
Overview
Laboratory findings of pheochromocytoma include elevated 24-hour urinary fractionated catecholamines and metanephrines for low-risk patients and plasma fractionated metanephrines for high-risk ones.
Laboratory Findings
Diagnostic lab findings associated with pheochromocytoma include:
- Elevated plasma and urinary catecholamines and metanephrines
- Elevated urinary vanillyl mandelic acid
Indications of pheochromocytoma testing:[1]
- Triad of tachycardia, headache, and sweating.
- Episodes of palpitation, headache and tremors for unknown reasons.
- Hypertension at age <20 years), resistant hypertension.
- A family history of pheochromocytoma, multiple endocrine neoplasia types 2, neurofibromatosis type 1, or von Hippel-Lindau.
- The presence of bilateral, extra-adrenal or multiple tumors or a malignant tumor, should be seen as indications for genetic testing.
- An incidentally discovered adrenal mass that does not have imaging characteristics consistent with pheochromocytoma.
High-risk patients
- Plasma fractionated metanephrines are the first test if elevated; 24-hour urinary fractionated metanephrines, catecholamines, and imaging should be the second test for diagnosis. [2]
- High-risk patients include a family history of MEN2 and VHL syndrome or past history of pheochromocytoma.
- DIagnostic cutoffs to exclude pheochromocytoma are metanephrine <0.3 nmol/L and normetanephrine <0.66 nmol/L.[3]
Low-risk patients
- Twenty-four-hour urinary fractionated catecholamines and metanephrines are the tests of choice.[4]
- Twenty-four-hour urine fractionated metanephrines and catecholamines, results cut offs are:
- Normetanephrine >900 mcg/24 hours.
- Metanephrine >400 mcg/24 hours.
- Norepinephrine >170 mcg/24 hours.
- Epinephrine >35 mcg/24 hours.
- Dopamine >700 mcg/24 hours.
- No further evaluation is necessary if results are negative.
NB: Discontinue TCAs two weeks before any hormonal assessments because they interrupt 24-hour urinary catecholamines metabolism.[5]
Patients with spells of elevated blood pressure (sudden onset of a symptom or symptoms) can be negative during in-between spells and should be tested directly after the attacks.[6]
Genetic testing:
It is suggested for:
- Bilateral adrenal pheochromocytoma.
- A family history of Von Hippel-Lindau syndrome, MEN2 and neurofibromatosis type 1.
- Paraganglioma.
- Unilateral pheochromocytoma at a young age.
It is autosomal dominant inheritance and has two pathways of tumor pathogenesis. Cluster 1 tumors are noradrenergic and extra adrenal except VHL. Cluster 2 tumors are adrenergic.[3]
| Cluster 1 | Cluster 2 |
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References
- ↑ Gimenez-Roqueplo AP, Lehnert H, Mannelli M, Neumann H, Opocher G, Maher ER; et al. (2006). "Phaeochromocytoma, new genes and screening strategies". Clin Endocrinol (Oxf). 65 (6): 699–705. doi:10.1111/j.1365-2265.2006.02714.x. PMID 17121518.
- ↑ Lenders JW, Pacak K, Walther MM, Linehan WM, Mannelli M, Friberg P; et al. (2002). "Biochemical diagnosis of pheochromocytoma: which test is best?". JAMA. 287 (11): 1427–34. PMID 11903030.
- ↑ Lenders JW, Keiser HR, Goldstein DS, Willemsen JJ, Friberg P, Jacobs MC; et al. (1995). "Plasma metanephrines in the diagnosis of pheochromocytoma". Ann Intern Med. 123 (2): 101–9. PMID 7778821.
- ↑ Sawka AM, Jaeschke R, Singh RJ, Young WF (2003). "A comparison of biochemical tests for pheochromocytoma: measurement of fractionated plasma metanephrines compared with the combination of 24-hour urinary metanephrines and catecholamines". J Clin Endocrinol Metab. 88 (2): 553–8. doi:10.1210/jc.2002-021251. PMID 12574179.
- ↑ Gimenez-Roqueplo AP, Lehnert H, Mannelli M, Neumann H, Opocher G, Maher ER; et al. (2006). "Phaeochromocytoma, new genes and screening strategies". Clin Endocrinol (Oxf). 65 (6): 699–705. doi:10.1111/j.1365-2265.2006.02714.x. PMID 17121518.
- ↑ Young WF, Maddox DE (1995). "Spells: in search of a cause". Mayo Clin Proc. 70 (8): 757–65. PMID 7630214.