Renal Function Monitoring for Abiraterone in Prostate Cancer
Monitor serum electrolytes (particularly potassium and phosphate), blood pressure, and liver function tests closely during abiraterone therapy, as mineralocorticoid excess effects including hypokalemia (28% incidence) and hypertension (22% incidence) are common and can lead to serious complications. 1
Baseline Assessment Requirements
Before initiating abiraterone, obtain:
- Serum potassium and phosphate levels to establish baseline values 2
- Blood pressure measurement to identify pre-existing hypertension 2
- Liver function tests (AST/ALT) as hepatotoxicity occurs in 7% of patients 1
- Cardiac evaluation in patients with cardiovascular risk factors 2
- Renal function assessment (serum creatinine/eGFR), though abiraterone pharmacokinetics are not significantly altered in end-stage renal disease 3
Ongoing Monitoring Protocol
Electrolyte Monitoring
- Check serum potassium at every visit during therapy, as hypokalemia is the most common electrolyte abnormality (28% of patients) 1
- Monitor serum phosphate levels regularly, as hypophosphatemia occurs in 24% of patients 1
- Severe hypokalemia can cause ascending flaccid paralysis, even when prednisone is co-administered 4
Blood Pressure Surveillance
- Monitor blood pressure at each clinical visit to detect mineralocorticoid excess 1
- Severe hypertension (grade 3-5) occurs in 4-10% of patients, requiring dose adjustment or discontinuation 1
- Hypertension is more common in elderly patients (≥70 years) who experience higher rates of grade 3-5 adverse events (47% vs 33%) 1
Hepatic Function Monitoring
- Check liver function tests (AST/ALT) regularly throughout treatment 1
- Grade 3-5 liver toxicity occurs in 7% of patients and is a common reason for drug discontinuation (11-12%) 1
- Elevated transaminases are the most common adverse event leading to discontinuation 1
Renal Function Considerations
- Routine renal function monitoring is not specifically mandated by guidelines, as abiraterone pharmacokinetics are unchanged in end-stage renal disease 3
- However, monitor creatinine in patients developing severe hypokalemia or hypertension, as these can secondarily affect renal function 5
- Rare cases of acute kidney injury have been reported, including rhabdomyolysis-induced AKI and drug-induced tubular damage 6, 7
Critical Monitoring Pitfalls
Mineralocorticoid Excess Recognition
- Signs include hypertension, hypokalemia, and peripheral edema 1
- 12% of patients may require prednisone initiation or dose escalation for mineralocorticoid toxicity management 5
- Patients with lower baseline androgen levels (androstenedione, androsterone, DHEA, 17-hydroxyprogesterone) are more likely to develop mineralocorticoid toxicity 5
High-Risk Populations
- Elderly patients (≥70 years) require more intensive monitoring due to higher toxicity rates and treatment-related deaths (9 vs 3 in younger patients) 1
- Monthly monitoring of blood pressure, potassium, phosphate, and liver function is recommended for elderly patients 8
Cardiac Monitoring
- Cardiac disorders occur in 19% of patients (6% serious) and include atrial fibrillation (4%) and ischemic heart disease 1, 2
- Cardiac events are a leading cause of drug discontinuation (<1% but clinically significant) 1
Management of Abnormalities
- Abiraterone must be taken on an empty stomach (1 hour before or 2 hours after meals) to avoid unpredictable drug levels 3
- Co-administration with prednisone 5 mg twice daily is mandatory to prevent ACTH-mediated mineralocorticoid excess 1
- Continue therapy until clinical progression or intolerability, not just PSA or radiographic changes that may represent flare 1