Kidney Donation Eligibility with Localized Oropharyngeal Amyloidosis
Based on the comprehensive workup showing no evidence of systemic disease, this patient can be considered a suitable kidney donor, provided all standard living donor criteria are met. 1, 2
Critical Distinction: Localized vs. Systemic Disease
The fundamental issue is distinguishing truly localized amyloidosis from systemic AL amyloidosis, which would absolutely contraindicate donation. The provided flow cytometry and peripheral blood smear results are reassuring:
- No abnormal plasma cell population detected - This is crucial, as systemic AL amyloidosis requires a clonal plasma cell population producing amyloidogenic light chains 3, 4
- Polytypic B cells without immunophenotypic abnormality - Rules out a monoclonal B-cell population 2
- No increase in CD34+ blasts - Excludes other hematologic malignancies 2
Systemic AL amyloidosis affects the kidney in approximately 70% of patients with nephrotic syndrome and progressive dysfunction, making it incompatible with donation. 1, 2 However, localized amyloidosis confined to the oropharynx for 6 years without systemic progression represents a fundamentally different disease entity. 1
Mandatory Pre-Donation Evaluation Requirements
Renal Assessment
- Proteinuria screening: Urine albumin excretion must be <30 mg/day for donation approval 1, 2
- GFR measurement: Use cystatin C-based methods (more accurate than creatinine-based) with required GFR ≥90 mL/min/1.73 m² 1, 2
- Blood pressure: Must be <140/90 mm Hg on at least two measurements 2
Cardiac Evaluation
Cardiac involvement would indicate systemic disease and absolutely contraindicate donation: 1, 2
- NT-proBNP or BNP levels - Elevated levels suggest cardiac amyloid deposition 2
- Echocardiography - Assess for restrictive cardiomyopathy patterns characteristic of cardiac amyloidosis 2
Additional Systemic Disease Screening
- Hepatic assessment: Alkaline phosphatase, liver size evaluation 2
- Neurologic examination: Peripheral or autonomic neuropathy would suggest systemic disease 2
- Serum and urine immunofixation: Confirm absence of monoclonal protein 2
Risk Assessment and Informed Consent
Donor-Specific Risks
The standard living donor risks apply: 2
- 30% reduction in GFR post-donation
- Low absolute risk of end-stage renal disease
- Perioperative complications
Theoretical Progression Risk
The donor must understand the theoretical (though unlikely after 6 years) risk of localized disease progressing to systemic amyloidosis over time. 1 However, the 6-year stability without systemic manifestations is highly reassuring.
No Transmission Risk to Recipient
There is no risk of amyloid recurrence in the transplanted kidney when disease is truly localized, as this concern only applies to systemic disease where circulating amyloidogenic proteins can deposit in the graft. 2, 5 The recipient faces no additional risk from this donor's localized oropharyngeal amyloidosis.
Post-Donation Monitoring Protocol
Standard Donor Follow-up
Amyloidosis-Specific Surveillance
- Periodic serum and urine immunofixation to detect any emergence of monoclonal protein suggesting evolution to systemic disease 2
- Clinical assessment for new symptoms suggesting organ involvement 1
Common Pitfalls to Avoid
Do not confuse localized amyloidosis with systemic AL amyloidosis - they have completely different prognoses and implications. The absence of a clonal plasma cell population on flow cytometry is the key distinguishing feature. 3, 4
Do not use creatinine-based GFR estimates alone - cystatin C-based measurements are more accurate and should be prioritized in this evaluation. 1, 2
Do not proceed without cardiac evaluation - cardiac involvement is the most serious manifestation of systemic AL amyloidosis and the main prognostic factor for mortality. 3, 4 Its absence must be confirmed.