Normetanephrine, 24 Hrs Urine

How is the test result interpreted?

The assay determines plasma Nor metanephrine which is a metabolite of catecholamines. Adrenaline, Noradrenaline, Dopamine are catecholamines present in plasma at low concentrations. Less than the three-fold elevation of catecholamines are observed in individuals with Essential Hypertension. Greater than three-fold levels of catecholamines of persistent or episodic nature is observed in Pheochromocytoma. Drug-related variance in catecholamine levels is seen in individuals on alpha methyldopa,metanamine mandelate and labetol. Discontinuation of these medications one week prior to catecholamine assay ensures the accuracy of the results. Interference in catecholamine assay due to synthetic catecholamines analyses e.g. isoproterenol and isoetharine need correlation with clinical inputs.

In individuals with clinical signs and symptoms of pheochromocytoma with normal catecholamine levels, evaluation of 24-hour urinary catecholamines or urinary metanephrine is recommended; to rule out the possibility of episodic elevation in plasma catecholamine levels.

What are Catecholamines?

Dopamine, Norepinephrine, and Epinephrine are catecholamines. These are organic compounds having a catechol ring and a side chain amine, secreted from adrenal galnds and nervous tissue and can act as both hormones and neurotransmitters. They are derived from amino acid Tyrosine and Phenylalanine.

What are the functions of Catecholamines?

Norepinephrine and dopamine act as neurotransmitters in the CNS and as hormones in circulation. Norepinephrine is a neuromodulator in PNS.

What is fight or flight response?

It is an automatic physiological response triggered by stressful or dangerous situations which are carried out by the sympathetic nervous system and prepare a person to fight or flee from a dangerous situation.

What is Pheochromocytoma?

It is a neuroendocrine tumour of the medullary part of the Adrenal gland leading to the release of a massive amount of Catecholamines in circulation.

Which genetic syndromes are associated with Pheochromocytoma?

VHL, MEN2,NF are the syndromes associated with Pheochromocytoma.

What are Adrenal glands?

Also known as Suprarenal glands, they are present at the top of the kidneys. It has two parts, cortex and medulla. The cortex secretes Mineralocorticoides, glucocoricoides and androgen whereas the medullary part secretes Catecholamines.

Which age group is affected?

Mostly pheochromocytoma occurs between 30 to 50 age group but can occur at any age.

What are symptoms of high Norepinephrine and other Catecholamines?

Signs and symptoms are related to hyperactivity of the sympathetic nervous system. Headache due to hypertension, Tachycardia, and excessive sweating, anxiety are the classic symptoms. Apart from this, heat intolerance, weight loss, nausea, constipation, orthostatic hypertension can also be seen.

Is there any difference between Norepinephrine and Noradrenaline?

They are the same.

Is this condition treatable?

This condition is mostly treatable by surgery by complete Adrenalectomy.

How to collect urine samples?

Laboratory personnel will give you a special kind of urine container with preservatives. Discard the early morning first urine, start collecting from the second one till the next morning first sample. Keep the container in the refrigerator till the sample is delivered to the laboratory.

Is fasting required for blood samples?

No, it is not required.

Is there a chance of a false-positive result?

Any kind of anxiety may lead to the release of catecholamines in circulation. While collecting blood samples if the patient is anxious, this might give a false-positive results. Hence 24-hour urine sample is the preferred method to test Catecholamines.

How Catecholamines are metabolized?

They have half-life of few minutes in circulation and are degraded by Catechol O Methyl Transferase or Monoamine oxidase to Metanephrine and normetanephrine. The end product of epinephrine and norepinephrine is VMA i.e. Vanillylmandelic acid which is excreted in the urine. Dopamine catabolism leads to the production of Homovanillic acid.

Conditions that mimic Pheochromocytoma?

Thyrotoxicosis, Hypoglycemia can mimic pheochromocytoma.

Is Pheochromocytoma malignant?

Mostly this is a benign tumor, chances of Malignancy are 10 percent.

Is it a genetic condition?

Most often it is sporadic in nature but the genetic syndrome is found in almost one-third cases.

Which specialist should be consulted?

This condition needs a multidisciplinary approach. Endocrinologist to manage hormone imbalance, surgeon and anesthetist for adrenalectomy, Radiotherapist for radio ablation of tumour, and also primary care physician.

Which tests should be done along with Nor Metanephrine?

Ct scan and MRI are required for localization of tumor. Plasma or urine noradrenaline levels, VMA may require too.

Can this condition be present without symptoms?

Almost 10 percent of cases are detected incidentally and patient have subclinical Pheochromocytoma.

What is Paraganglioma?

Paraganglioma is tumor arising from a special type of nerve cells called Chromaffin cells. If this tumour occurs in the Adrenal gland it is called Pheochromocytoma and in the rest of the body it is referred to as Paraganglioma.

What is the Prognosis or chances of recovery of Pheochromocytoma?

In the case of sporadic disease chances of recovery are good but if the lesion is malignant or metastasized then survival is reduced significantly.