What labs and imaging are used to monitor a left adenoma?

Monitoring Left Adrenal Adenoma

For a left adrenal adenoma, monitoring requires both biochemical surveillance with liver function tests every 6 months and imaging surveillance with contrast-enhanced MRI or CT every 6-12 months, with the specific frequency and duration determined by adenoma size, functional status, and risk features. 1, 2

Initial Diagnostic Workup

Before establishing a monitoring protocol, complete characterization is essential:

• Imaging characterization: Contrast-enhanced MRI is preferred over CT for better characterization of adenoma subtypes and to distinguish benign from malignant lesions 3, 2
• Noncontrast CT density measurement: Lesions with attenuation ≤10 Hounsfield units are highly specific for benign adenomas (>95% specificity), while delayed contrast washout patterns further improve diagnostic accuracy 3
• Endocrine function testing: All patients require screening for subclinical hormone hypersecretion, including 24-hour urine cortisol, plasma metanephrines, and aldosterone-to-renin ratio if hypertensive, as 12-23% of incidentalomas demonstrate subclinical function 3, 4, 5

Size-Based Monitoring Algorithm

Adenomas <3 cm Without Known Malignancy History

• Imaging frequency: Repeat imaging at 6-12 months initially, then annually if stable 3
• Laboratory monitoring: Liver function tests every 6 months 1, 2
• Duration: Can consider stopping surveillance after 2-3 years of stability in truly benign, non-functional lesions <3 cm 3

Adenomas 3-5 cm

• Imaging frequency: Contrast-enhanced MRI or CT every 6-12 months 1, 2
• Laboratory monitoring: Liver function tests every 6 months 1, 2
• Duration: Lifelong surveillance due to increased risk of complications 1, 2
• Caveat: Size >3 cm in patients with cancer history has >95% malignancy rate, requiring more aggressive evaluation 3

Adenomas >5 cm

• Strong recommendation for resection rather than surveillance, as hemorrhage risk increases significantly and tumor size >5 cm is the most significant risk factor for complications 1, 2
• If surgery declined or contraindicated, imaging every 3-6 months with contrast-enhanced MRI or CT 1, 2
• Liver function tests every 6 months 1, 2

Critical Warning Signs Requiring Immediate Evaluation

Monitor for features suggesting malignant transformation or complications:

• Sudden increase in size or number of lesions on surveillance imaging 2
• Increased vascularity or changes in imaging characteristics (loss of typical adenoma features like lipid content) 2
• Development of symptoms: New abdominal pain, palpable mass, or signs of hemorrhage 1
• Biochemical changes: New or worsening hormone hypersecretion (cortisol, androgens, aldosterone) 4, 5

Important caveat: Alpha-fetoprotein and carcinoembryonic antigen levels remain normal even with malignant transformation and cannot reliably predict malignancy 1, 2

Functional Adenoma Considerations

If the adenoma demonstrates hormone hypersecretion:

• Cortisol-secreting: Monitor for progression of Cushing syndrome with 24-hour urine free cortisol, morning cortisol, and ACTH levels every 6 months 4
• Aldosterone-secreting: Monitor blood pressure control, serum potassium, and aldosterone-to-renin ratio every 6 months 5
• Androgen-secreting: Monitor testosterone, androstenedione, and DHEA-S levels every 6 months 4
• Functional adenomas warrant more aggressive management with strong consideration for surgical resection regardless of size 4, 5

Special Population: Patients with Cancer History

In patients with known malignancy elsewhere, the threshold for concern is dramatically lower:

• Lesions >3 cm have >95% malignancy rate in this population 3
• More frequent imaging (every 3-6 months) is warranted 3
• Lower threshold for biopsy or surgical intervention 3

When to Stop Surveillance

Surveillance can potentially be discontinued in highly selected cases:

• Truly benign adenomas <3 cm with typical imaging features (low attenuation on noncontrast CT, rapid contrast washout) 3
• Non-functional status confirmed by comprehensive endocrine testing 3
• Stable size for 2-3 years on serial imaging 3
• No cancer history and no high-risk features 3

However, for adenomas ≥3 cm or those with any concerning features, lifelong surveillance is necessary due to ongoing risk of growth, malignant transformation, or development of new lesions 1, 2