Pheochromocytoma

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Pheochromocytoma Aug 2nd 2013, 10:57 Pheochromocytoma is a rare tumor of the adrenal glands that secretes the catecholamines, adrenaline and noradrenaline. The clinical features are usually consequences of the high blood pressure caused by the catecholamines. Pheochromocytoma is a rare tumor of the adrenal glands. This pair of glands is situated one above each kidney. They have two layers, the outer layer is referred to as cortex and the inner layer is called the medulla. The cortex secretes hormones like hydrocortisone and aldosterone. The medulla on the other hand, secretes adrenaline, a substance similar to noradrenaline secreted by certain nerves forming the sympathetic nervous system. Adrenaline and noradrenaline are secreted at times of stress and are responsible for changes in the body that give rise to the 'fight or flight' response. They are chemically referred to as catecholamines. Pheochromocytoma is a tumor of the adrenal medulla that releases large amounts of adrenaline and noradrenaline into the blood stream. It is a rare tumor, affecting around 1 or 2 people out of every million individuals. It can occur at any age, but is most commonly found during the middle age. Sometimes, it arises from similar tissue outside the adrenal glands; these are referred to as paragangliomas. Paragangliomas are usually located in the abdomen, though they may arise from some other sites as well. Pheochromocytomas are usually benign. However, in around 10% cases, they may turn malignant. In some cases, pheochromocytomas may be inherited. In such cases, they may be associated with certain syndromes namely, von Hippel-Lindau (VHL) syndrome, multiple endocrine neoplasia type 2 (MEN 2), and neurofibromatosis type 1 (NF1). The presence of these symptoms should be ruled out in a patient with pheochromocytoma. What are the Symptoms and Signs of Pheochromocytoma? In many cases, pheochromocytomas do not cause any symptoms and may be diagnosed when an autopsy is done for some other purpose. In other cases, the patients' symptoms are due to the excessive secretion of adrenaline and noradrenaline into the blood and the consequent increase in blood pressure. The patient may suffer from the following symptoms: Headache Palpitation and chest pain Abdominal pain Excessive sweating Nausea, weakness Excessive anxiety Constipation Weight loss On examination, the patient is likely to have a high blood pressure. Other findings include: Increase in pulse rate Irregular cardiac rhythms, referred to as Arrhythmias Pallor Tremors Damage to the inner layer of the eye, the condition called hypertensive retinopathy Increase in blood sugar levels The frequency and severity of symptoms progress as the tumor increases in size. If it is not diagnosed and treated on time, the condition could be life threatening. How can we Diagnose Pheochromocytoma? A patient with the above symptoms and persistently high blood pressure should be evaluated for pheochromocytoma. Diagnosis of pheochromocytoma is based on the following tests: Blood and urine tests: Blood and urine tests show increased levels of adrenaline and noradrenaline. The urine tests are conducted on urine that has been collected for 24 hours. In addition, the metabolites of adrenaline and noradrenaline are also increased in the blood and urine and measurement of their levels helps in the diagnosis of pheochromocytoma. These metabolites include normetanephrine, metanephrine and vanillylmandelic acid (VMA). Imaging studies: Imaging studies like CT scan or MRI of the abdomen help to locate the position of the tumor and determine its size. What are the Complications of Pheochromocytoma? If pheochromocytoma is not treated, the persistent rise in blood pressure can give rise to the following complications: Heart failure Kidney failure Stroke Impairment of vision, which can progress to blindness How can Pheochromocytoma be Treated? Initial treatment of pheochromocytoma is directed to controlling the blood pressure and other effects of adrenaline and noradrenaline. These catecholamines bring about their effect by acting on specific receptors called alpha and beta receptors. Therefore, blocking these receptors helps to control the symptoms to some extent. Medications: The hypertensive crisis is managed by treating the patients with drugs that block alpha as well as beta receptors like phenoxybenzamine. Alternatively, alpha blockers like prazosin are given first, followed by beta blockers like propranolol and esmolol. Surgery: Surgical removal of the tumor is possible if it is localized. The patient should be stabilized before surgery is undertaken.

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