Is it safe to use a potential kidney donor with localized oropharynx (throat) Amyloid Light-chain (AL) amyloidosis?

Kidney Donation with Localized Oropharyngeal AL Amyloidosis

A potential kidney donor with truly localized oropharyngeal AL amyloidosis can safely donate a kidney, provided comprehensive evaluation confirms the disease is genuinely localized without systemic involvement. 1

Critical Distinction: Localized vs. Systemic Disease

The fundamental issue is confirming that the amyloidosis is truly localized rather than systemic AL amyloidosis, which would be an absolute contraindication to donation.

• Localized AL amyloidosis represents only 7% of all AL amyloidosis cases and has an entirely different prognosis than systemic disease, with 10-year survival of 78% (equivalent to the general population) and zero documented cases of systemic progression 2
• Systemic AL amyloidosis affects the kidney in approximately 70% of patients, typically presenting with nephrotic syndrome and progressive kidney dysfunction, making it incompatible with donation 3
• The oropharyngeal/laryngeal region is a recognized site for localized AL amyloidosis, accounting for 14% of localized cases in the largest published series 2

Mandatory Pre-Donation Evaluation

The donor must undergo rigorous testing to exclude any evidence of systemic disease:

Hematologic Assessment

• Serum and urine immunofixation must be negative to confirm absence of monoclonal protein, which would indicate systemic disease 2
• Serum free light chain assay should be performed to assess for clonal plasma cell disorder 1
• Bone marrow biopsy is not routinely required if serum and urine immunofixation are negative 2

Kidney-Specific Evaluation

• Screen for proteinuria with urine albumin excretion rate, which must be <30 mg/day for donation approval 3, 1
• Measure GFR using cystatin C-based methods rather than creatinine-based estimates, as cystatin C is more accurate and independent of muscle mass 3, 1
• GFR must be ≥90 mL/min/1.73 m² for donation 3
• Blood pressure must be <140/90 mm Hg on at least two measurements 3

Cardiac Assessment

• Evaluate for cardiac involvement with NT-proBNP or BNP levels and echocardiography, as cardiac involvement would indicate systemic disease and contraindicate donation 3, 1
• Any evidence of restrictive cardiomyopathy or elevated cardiac biomarkers suggests systemic AL amyloidosis 4

Additional Screening

• Assess for hepatic involvement (alkaline phosphatase, liver size) 3
• Evaluate for peripheral or autonomic neuropathy, which would suggest systemic disease 3

Risk Assessment and Informed Consent

If all evaluations confirm truly localized disease, the donor faces standard living donation risks without additional amyloid-specific concerns:

• The theoretical risk of localized amyloidosis progressing to systemic disease exists but has never been documented in published series 2
• There is no risk of amyloid recurrence in the transplanted kidney when disease is truly localized, as this concern only applies to systemic disease 1
• Standard living donor risks apply: 30% reduction in GFR post-donation, low absolute risk of ESRD, and perioperative complications 3

The donor must be counseled about:

• The importance of distinguishing localized from systemic disease
• The need for lifelong post-donation monitoring
• The possibility (though undocumented) of future systemic progression
• Standard living donor risks and recovery expectations 1

Post-Donation Monitoring Protocol

Enhanced surveillance is warranted given the amyloid history:

• Annual monitoring for proteinuria and kidney function (standard for all donors) 3, 1
• Periodic reassessment of serum and urine immunofixation to detect any emergence of monoclonal protein 1
• Continued surveillance of the original oropharyngeal site for local recurrence 2
• Maintain awareness that 17% of localized AL amyloidosis patients experience local recurrence, though this does not affect systemic health or donated kidney 2

Key Pitfalls to Avoid

Do not proceed with donation if:

• Serum or urine immunofixation is positive (indicates systemic disease) 2
• Any proteinuria is present (albumin excretion ≥30 mg/day) 3
• Cardiac biomarkers are elevated or echocardiography shows abnormalities 3
• There is evidence of plasma cell dyscrasia on laboratory testing 5

Common diagnostic error: Assuming all AL amyloidosis is systemic—localized disease has fundamentally different biology and prognosis 2