Related Experiment Video
Updated: Sep 27, 2026

A Convenient Method for Extraction and Analysis with High-Pressure Liquid Chromatography of Catecholamine Neurotransmitters and Their Metabolites
Published on: March 1, 2018
Phaeochromocytoma with normal urinary catecholamines: the potential value of urinary free metadrenalines
1Biochemistry Department, Crosshouse Hospital, Kilmamock KA2 OBE, UK. fraser.davidson@aaaht.scot.nhs.uk
Background:
Normal urine catecholamine values in patients with phaeochromocytoma is an occasional finding and may lead to a missed diagnosis. Additional urinary free metadrenaline analysis may be of value in this situation.
Methods:
In addition to vanillylmandelic acid, homovanillic acid and the catecholamines, urinary free normetadrenaline (fNMA) and free metadrenaline (fMA) were measured. This report describes six confirmed cases of phaeochromocytoma showing normal urinary catecholamine output and compares fMA results and tumour size with other confirmed cases where the urine catecholamines were increased.
Results:
Urine catecholamines in these patients with, on average, smaller tumours, were all normal. Urinary fNMA and fMA were available on five patients, and were increased in three. The data suggest that, unlike the catecholamines, urinary fNMA and fMA could be a useful predictor of tumour size.
Conclusion:
The inclusion of fNMA and fMA in the test profile is likely to be of additional benefit in tumour detection, particularly when catecholamines or other metabolites are normal.
Related Concept Videos
Adrenergic Neurons: Neurotransmission
Synthesis: Catecholamine synthesis requires tyrosine, which is taken...
Adrenal Gland Disorders
Adrenal insufficiency, characterized by insufficient cortisol and aldosterone production, leads to conditions like Addison's disease. This disorder, affecting the adrenal cortex, exhibits symptoms such as skin bronzing, dehydration, low blood pressure, fatigue, and weight loss. Congenital adrenal hyperplasia, a genetic ailment causing...
Cushing Syndrome II: Pathophysiology
Drugs Affecting Neurotransmitter Release or Uptake
Adrenergic Agonists: Indirect-Acting Agents
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral bioavailability, and...
Adrenergic Agonists: Direct-Acting Agents
These agents can be classified...

