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
An elevated concentration of the following is diagnostic of pheochromocytoma.
- Elevated plasma and urinary catecholamines and Plasma fractionated metanephrines levels
- Elevated urinary [[vanillyl mandelic acid] [1]
- Diagnostic cutoffs to exclude pheochromocytoma are:
- Metanephrine <0.3 nmol/L
- Normetanephrine <0.66 nmol/L. [2]
The cut-off values are as follows:[3]
- 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
The following drugs interfere with urinary catecholamines metabolism and shoudl be discontinued two weeks before any hormonal assessments: [4]
- Tricyclic antidepressants (TCAs)
- Levodopa
- Antipsychotics
- Ethanol
- Acetaminophen
- Phenoxybenzamine [5]
Patients with spells of elevated blood pressure (sudden onset of a symptom or symptoms) can be negative in-between spells and should be tested directly after the attacks.[6]
References
- ↑ 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.
- ↑ Kudva YC, Sawka AM, Young WF (2003). "Clinical review 164: The laboratory diagnosis of adrenal pheochromocytoma: the Mayo Clinic experience". J Clin Endocrinol Metab. 88 (10): 4533–9. doi:10.1210/jc.2003-030720. PMID 14557417.
- ↑ Young WF, Maddox DE (1995). "Spells: in search of a cause". Mayo Clin Proc. 70 (8): 757–65. PMID 7630214.