Can pheochromocytoma cause urinary retention?

Pheochromocytoma Can Cause Urinary Retention

Yes, pheochromocytoma can cause urinary retention through alpha-adrenergic effects on the bladder neck and urethra. This connection is supported by urodynamic studies demonstrating increased urethral closure pressure in patients with pheochromocytoma 1.

Pathophysiological Mechanism

The mechanism by which pheochromocytoma causes urinary retention involves:

1. Alpha-adrenergic stimulation: Pheochromocytomas secrete excess catecholamines (primarily norepinephrine) that stimulate alpha receptors in the bladder neck and urethra 1.

2. Increased urethral tone: Studies have demonstrated increased urethral closure pressure in 8 of 10 pheochromocytoma patients, regardless of their specific catecholamine secretion pattern 1.

3. Reversible with alpha-blockade: Urodynamic studies show that administration of alpha-adrenergic blocking agents (like thymoxamine) reduces urethral pressure in these patients, confirming the adrenergic mechanism 1.

Clinical Relevance

This relationship between pheochromocytoma and urinary symptoms has important clinical implications:

• Unusual presentation: While the classic triad of pheochromocytoma symptoms includes headache, sweating, and palpitations, urinary symptoms can be an atypical initial presentation 2.

• Diagnostic clue: Unexplained urinary retention, especially when accompanied by hypertension (either sustained or paroxysmal), should prompt consideration of pheochromocytoma in the differential diagnosis.

• Preoperative management: Alpha-adrenergic blockade, which is standard preoperative preparation for pheochromocytoma patients, may also improve urinary symptoms by reducing urethral pressure 3.

Diagnostic Approach

When urinary retention is present with suspicious symptoms:

1. Biochemical testing: Measure plasma free metanephrines or 24-hour urinary fractionated metanephrines 3.

2. Imaging: If biochemical tests are positive, proceed with abdominal CT or MRI to locate the tumor 3.

3. Functional imaging: For suspected metastatic disease, consider meta-iodobenzylguanidine (MIBG) scanning or other functional imaging 4, 3.

Management Considerations

For patients with pheochromocytoma presenting with urinary retention:

• Preoperative alpha-blockade: Essential for all pheochromocytoma patients, with treatment for 10-14 days before surgery 3. This may also improve urinary symptoms.

• Surgical approach: Complete surgical resection is the definitive treatment, with laparoscopic adrenalectomy recommended for smaller tumors (<8 cm) without invasiveness 3.

• Post-surgical follow-up: Urinary symptoms typically resolve after tumor removal, as demonstrated by normalization of urodynamic parameters in post-operative studies 1.

Special Considerations

• Bladder pheochromocytomas: Rarely, pheochromocytomas can arise from the urinary bladder itself (paragangliomas), which may present with hematuria and post-micturition hypertension in addition to urinary symptoms 5.

• Genetic testing: Approximately 25% of pheochromocytomas are hereditary, so genetic counseling should be considered for all patients 3.

• Long-term follow-up: Patients require lifelong surveillance, especially those with genetic syndromes, extra-adrenal disease, or larger tumors 3.

In conclusion, urinary retention is a recognized but uncommon manifestation of pheochromocytoma that occurs due to alpha-adrenergic stimulation of the bladder neck and urethra. Recognition of this association can aid in earlier diagnosis and appropriate management of these potentially life-threatening tumors.