Pheochromocytoma laboratory findings: Difference between revisions

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==Overview==
==Overview==
Laboratory findings consistent with the diagnosis 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 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==
==Laboratory Findings==

Revision as of 17:25, 7 July 2017

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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]

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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:

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 type 2, neurofibromatosis type 1, or von Hippel-Lindau.
  • Presence of bilateral, extra-adrenal or multiple tumours or a malignant tumour, 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 is the first test, if elevated; 24-hour urinary fractionated metanephrines, catecholamines, and imaging shuld be the second test for diagnosis. [2]

High risk patients include: 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: 24-hour urinary fractionated catecholamines and metanephrines.[4]

24-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 eleveated blood pressure (sudden onset of a symptom or symptoms) can be negative during inbetween spells and should be ltested directly after the attacks.[6]

Genetic testing :

It is suggested for:

  • Bilateral adrenal pheochromocytoma.
  • 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
  • Succinate dehydrogenase (SDH) subunit genes
  • Von Hippel-Lindau (VHL) disease
  • Fumarate hydratase gene mutations
  • Multiple endocrine neoplasia type 2A
  • Multiple endocrine neoplasia type 2B
  • Neurofibromatosis type 1 (NF1)

References

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. Young WF, Maddox DE (1995). "Spells: in search of a cause". Mayo Clin Proc. 70 (8): 757–65. PMID 7630214.


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