- Pheochromocytoma is a rare tumor of the adrenal medulla that secretes excess catecholamines, leading to episodic headaches, sweating, and tachycardia. - Diagnosis involves measuring levels of catecholamines and metanephrines in urine or plasma samples. Imaging tests such as CT, MRI, or MIBG scans are also used. - Treatment begins with alpha-blockade prior to surgery to remove the tumor, followed by long-term use of alpha-blockers or calcium channel blockers to control blood pressure.

1. Dr.Mostafa Hegazy

2. Signs and Symptoms

3. Episodic headache
Sweating
Tachycardia

4. Other symptoms
• Sustained or paroxysmal hypertension is the most common
sign, however 5-15% have normal blood pressure
• Mild to severe headache in 90% of patients
• Generalized sweating in 60-70%
• Palpitations
• Dyspnea
• Generalized weakness
• Panic attack type symptoms
• Pallor
• orthostatic hypotension
• visual blurring
• papilledema
• weight loss
• polyuria

5. Pathophysiology

7. • Catecholamines exhibit peripheral nervous system
excitatory and inhibitory effects as well as actions in the
CNS such as respiratory stimulation and an increase in
psychomotor activity.
• The excitatory effects are exerted upon smooth muscle
cells of the vessels that supply blood to the skin and
mucous membranes.
• Cardiac function is also subject to excitatory effects,
which lead to an increase in heart rate and in the force
of contraction.
• Inhibitory effects,are exerted upon smooth muscle of the
gut, the bronchial tree, and blood vessels of the skeletal
muscle.

8. • In addition to their effects as neurotransmitters,
norepinephrine and epinephrine can influence the
rate of metabolism by modulating insulin secretion
and by increasing the rate of glycogenolysis and
fatty acid metabolism.
• Abnormalities in carbohydrate metabolism such as
insulin resistance, impaired fasting glucose, type 2
DM can occure.

9. When to suspect Pheochromocytoma
 Hyperadrenergic spells eg self-limited episodes of nonexertional
palpitations, diaphoresis, headache, tremor, pallor
 Resistant hypertension (<0.2% of patients with HTN have
pheochromocytoma)
 Pre-disposing familial syndrome eg MEN 2, NF1, VHL
 Family history of pheochromocytoma
 Incidentally discovered adrenal mass: 3-10% prove to be
pheochromocytomas
 Pressor response during anesthesia, surgery or angiography
 Onset of HTN < 20 years old
 Idiopathic dilated cardiomyopathy
 History of gastric stromal tumor or pulmonary chondromas (Carney
Triad)

10. DIAGNOSIS

11.  Historically: measured 24 hour urinary excretion of
catecholamines and total metanephrines
 Superior test: plasma fractionated metanephrines via liquid
chromatography with electrochemical detection or tandem mass
spectrometry
 96-100% sensitive and 85-89% specific and falls to 77% in
patients >60 years old
 Predictive value is high and normal test excludes
pheochromocytoma except in patients with early preclinical
disease and those with strictly dopamine-secreting tumors

12.  Tricyclic antidepressants interfere with assay most frequently
 Clonidine suppression test is confirmatory when plasma
fractionated metanephrines are positive: 0.3 mg is administered
orally, plasma catecholamines are measured before and 3 hours
after the dose. Clonidine will suppress catecholamines if excess
is due to essential hypertension, but will remain elevated in
pheochromocytoma
 Follow up with CT or MRI of abdomen and pelvis
 Consider MIBG scintgraphy where a compound resembling
norepinephrine is taken up by adrenal tissue if clinical suspicion
remains high

13. Medications that increase
measured catecholamine levels
 TCAs
 Levodopa
 Drugs containing adrenergic receptor agonists eg decongestants
 Amphetamines
 Buspirone and most psychoactive agents
 Prochlorperazine
 Reserpine
 Withdrawal from clonidine
 Ethanol
 acetominophen

14. Malignant Potential
 10% of tumors are extraadrenal, but 95% are within abdomen and
pelvis
 About 10% of all catecholamine-secreting tumors are malignant
 Histologically and biochemically identical to benign counterparts
 Local invasion or distant metastases can occur as long as 20 years
after resection
 Metastatic lesions should be resected if possible
 RFA of hepatic and bone metastases may be effective in selected
patients
 Combination chemotherapy can be considered

15. Treatment

16.  Start alpha-adrenergic blocker 7-10 days preoperatively
 Phenoxybenzamine is drug of choice: irreversible, long-acting,
non-specific alpha-adrenergic agent
 Initial dose is 10 mg b.i.d.; dose is increased by 10-20 mg in
divided doses every 2-3 days; final dose usually 20-100 mg daily
 Goal BP <120/80 seated and SBP > 90 standing
 High salt (> 5000 mg daily) recommended on 3rd day to
counteract catecholamine-induced volume contraction and
orthostasis, though caution advised in patients with CHF or CRI
 Following adequate alpha-blockade, beta blockade is initiated 2-3
days pre-operatively eg. Propranolol 10 mg q.6.h

17.  NEVER start beta blockade first; unopposed alpha adrenergic
stimulation can lead to further elevation in blood pressure
 Long-term treatment with selective alpha1-adrenergic
blockers such as prazosin, terazosin, doxazosin
 Calcium channel blockers are probably as effective, eg.
Nicardipine 30 mg b.i.d.
 Addition of metyrosine, a direct catecholamine synthesis
inhibitor, may improve perioperative course, though most
institutions reserve for those patients who cannot tolerate
the typical alpha + beta blockade combination. Side effects
include sedation, depression, diarrhea,anxiety, nightmares,
crystalluria and urolithiasis, galactorrhea, and
extrapyramidal signs