Cells derived form neuroendocrine tumours (e.g. Pheochromcytoma) are known to produce Catecholamines which are secreted episodically via vesicles into the blood stream. But beside this a small portion of the Catecholamines is metabolized inside the cells to the corresponding Catecholamines metabolites – namely Metanephrine, Normetanephrine and 3-methoxytyramine – which are secreted at low levels continuously into the blood stream.
Recent studies and publications have shown that the quantification of these plasma free metanephrine (fMN) and plasma free normetanephrine (fNMN) is the most accurate biochemical marker for the clinical diagnosis of Pheochromocytoma and follow-up of pheochromocytoma patients.
LDN has developed enzyme immunoassays and isotopic assays for the quantitative determination of fMN and fNMN in human plasma without extraction.

The assays show the following common features:

• speed and ease of use
• cost-effective
• for in-vitro diagnostic and research applications
• wide standard ranges
• available as ELISA and RIA (with 15 weeks shelf-life)
• the ELISA is automatable
• freedom from drug interferences
• excellent correlation with HPLC and LC-MS/MS
• single and multi parameter kits available

3-Methoxytyramine (3-MT)

Cells derived form neuroendocrine tumours (e.g. pheochromcytoma) are known to produce catecholamines which are secreted episodically via vesicles into the bloodstream.
But beside this a small portion of the catecholamines is metabolized inside the cells to the corresponding catecholamines metabolites – namely metanephrine, normetanephrine and 3-MT – which are secreted at low levels continuously into the bloodstream.
3-MT is a metabolite of the neurotransmitter Dopamine formed by the introduction of a methyl group to dopamine by the enzyme catechol-O-methyl transferase (COMT).
The measurement of 3-MT allows the detection of dopamine-producing tumours: For example a substantial number of patients with head-and-neck paragangliomas (HNPGL) have biochemically active tumors and only display increased excretion of 3-methoxytyramine, but not of other catecholamines or their metabolites.
The combined levels of free metanephrine/normetanephrine and free 3-MT in plasma indicate a higher number of biochemically active HNPGLs than the 24-h urinary excretion rates of these markers.

With this new assay LDN is now able to offer the most comprehensive panel worldwide for the measurement of PPGL-relevant parameters including:

• Urinary Metanephrine/Normetanephrine (free and total; ELISA&RIA)
• Plasma Metanephrine/Normetanephrine (ELISA&RIA)
• Catecholamines in plasma and urine (ELISA&RIA)
• Chromogranin A (ELISA)
• and – closing the diagnostic gap – 3-Methoxytyramine (RIA)