Chronic Allograft Dysfunction

The contract between this chapter and the reader.

1. 1. Define chronic allograft dysfunction and IFTA.
2. 2. Explain why ‘chronic allograft nephropathy’ was replaced by specific diagnoses.
3. 3. List the causes of the slowly failing graft.
4. 4. Use biopsy and serology to find the specific cause.
5. 5. Recognise recurrent disease and its variable risk.
6. 6. Identify the treatable recurrences.
7. 7. Recognise CNI nephrotoxicity as a chronic cause.
8. 8. Treat the specific cause and manage the graft as CKD.
9. 9. Understand the prognosis of chronic dysfunction.

A sixty-second reading. Each bullet stands alone.

• Chronic allograft dysfunction is a slow decline in graft function, often with proteinuria, over months to years.
• Its common histologic endpoint is interstitial fibrosis and tubular atrophy (IFTA) — nonspecific scarring.
• The outdated term ‘chronic allograft nephropathy’ was replaced because it lumped distinct, sometimes treatable causes.
• The causes include chronic antibody-mediated rejection, CNI nephrotoxicity, recurrent and de novo disease, BK nephropathy, and chronic TCMR.
• Biopsy, with serology and virology, identifies the specific cause — some of which are treatable.
• Recurrent glomerulonephritis varies in risk and treatability by the original disease.
• Recurrent primary FSGS can be early and dramatic and is treated with plasma exchange.
• Recurrent membranous nephropathy is treated with rituximab; atypical HUS with a complement inhibitor.
• IgA nephropathy commonly recurs but is usually indolent.
• CNI nephrotoxicity causes chronic injury (arteriolar hyalinosis) and may prompt minimisation or conversion.
• Chronic active antibody-mediated rejection is the leading immunologic cause of late graft loss.
• Much chronic dysfunction is irreversible, so the aim is to slow decline and treat what is treatable.
• The graft is managed as chronic kidney disease, with preparation for possible failure.

The medical core. An expert should agree chronic dysfunction and recurrent disease are fully covered here.

Why it matters at the bedside

Most grafts that fail late do so slowly — a creatinine creeping up, proteinuria appearing, over months and years. The temptation is to shrug and call it ‘chronic damage.’ The discipline is the opposite: to biopsy, to name the specific cause, and to find the treatable ones, because the difference between a recurrence you can treat and scarring you cannot is the difference between saving the graft and losing it.

The slowly failing graft and IFTA

• Chronic allograft dysfunction is a gradual decline in function, often with proteinuria, over months to years. Its histologic endpoint is interstitial fibrosis and tubular atrophy — IFTA — nonspecific scarring that is the final common pathway of many distinct injuries. IFTA tells you the graft is scarring; it does not, by itself, tell you why.

Why 'CAN' was abandoned

• For years such grafts were labelled with the catch-all ‘chronic allograft nephropathy,’ a term the Banff classification deliberately abandoned because it lumped together distinct processes — rejection, drug toxicity, recurrence, infection — some of them treatable, and so discouraged the search for a specific, actionable cause. The modern approach names the process, not the scar.

The causes

• The slowly failing graft has a definable differential: chronic active antibody-mediated rejection (the leading immunologic cause), chronic active T-cell-mediated rejection, calcineurin-inhibitor nephrotoxicity, recurrent disease (the original glomerulonephritis returning), de novo disease (a new glomerulonephritis), BK nephropathy if missed, and contributors such as hypertension, obstruction, and recurrent infection — with non-adherence often driving the chronic AMR.

The workup: finding the specific cause

• The investigation is built to assign a cause: an allograft biopsy is central (distinguishing AMR, recurrence, CNI toxicity, and BK morphologically), with donor-specific antibody for AMR, BK virology, quantified proteinuria, the PLA2R antibody for membranous recurrence, and complement studies for atypical HUS and C3 glomerulopathy. The goal is a named diagnosis, not a shrug.

Recurrent disease and its variable risk

• The original kidney disease can return in the graft, and the risk varies widely by disease: primary FSGS recurs commonly and sometimes dramatically; IgA nephropathy recurs commonly but is usually indolent; membranous nephropathy and MPGN/C3 glomerulopathy recur; atypical HUS recurs through complement dysregulation; primary hyperoxaluria recurs unless the metabolic defect is corrected by a liver transplant. Quiescent ANCA and anti-GBM disease recur infrequently.

The treatable recurrences

• Crucially, several recurrences are treatable. Recurrent primary FSGS — which can present early with heavy proteinuria — responds to plasma exchange (with rituximab in some); recurrent membranous nephropathy is treated with rituximab, monitored by PLA2R; recurrent atypical HUS is prevented and treated with a complement inhibitor. Recognising these turns a ‘chronic’ label into an actionable diagnosis.

CNI nephrotoxicity

• Calcineurin inhibitors contribute to chronic injury through afferent arteriolar hyalinosis and striped interstitial fibrosis. Where biopsy implicates CNI nephrotoxicity, the response is to minimise the calcineurin inhibitor or convert to a sparing agent (belatacept or an mTOR inhibitor, with their own trade-offs) — balanced, as ever, against the rejection risk of reducing it.

Treating the cause and managing as CKD

• Management is two-pronged: treat the specific cause where it is treatable — plasma exchange for recurrent FSGS, rituximab for membranous, a complement inhibitor for atypical HUS, immunosuppression reduction for BK, CNI minimisation for nephrotoxicity — and, for the much that is irreversible, slow the decline by managing the graft as chronic kidney disease (blood pressure, proteinuria with RAAS blockade, cardiovascular risk) and preparing for eventual failure, re-listing, and dialysis (the closing chapter).

Prognosis

• The honest prognosis: chronic dysfunction and IFTA are a leading cause of late graft loss, chronic active AMR is its dominant immunologic driver, and few therapies are proven for established chronic injury — which is exactly why the treatable recurrences must not be missed, and why prevention (adherence, adequate immunosuppression) matters more than any late rescue.

Five fully-built tables.

Table A — Causes of chronic dysfunction

Table B — Recurrent disease

Table C — The workup

Table D — Treatable versus largely irreversible

Table E — General management

Visualise & Map

Causal chains, each ending in a named action.

Chain 1 — The final common pathway

Multiple chronic insults → progressive scarring → IFTA (a nonspecific endpoint) → graft loss → ACTION: biopsy to name the specific, possibly treatable cause — do not lump.

Chain 2 — The immunologic driver

De novo DSA / non-adherence → chronic active AMR → transplant glomerulopathy → leading late graft loss → ACTION: prevent (adherence/adequate IS) and monitor DSA.

Chain 3 — Recurrent FSGS

A circulating permeability factor → recurrent primary FSGS → early heavy proteinuria → ACTION: treat with plasma exchange.

Chain 4 — Recurrent atypical HUS

Complement dysregulation persists after transplant → recurrent atypical HUS → thrombotic microangiopathy → ACTION: use a complement inhibitor.

Chain 5 — The drug as the cause

Chronic calcineurin-inhibitor exposure → arteriolar hyalinosis and striped fibrosis → chronic nephrotoxic injury → ACTION: minimise or convert the calcineurin inhibitor.

Numbered rules. These numbers are the cross-reference handle for the cases and flowcharts.

Clinical Reasoning

Five cases. Each stops you at a decision before it answers it.

Every mechanism from Level 3 earns a bedside consequence and an action.

Exhaustive. Every rule in the chapter is here.

Safety & Evidence

Panel A — Red flags

Panel B — NEVER DO

Anti-patterns clinicians fall into. Each becomes a Level 22 distractor.

The grade reflects strength of evidence, not importance.

Patient Decisions

Outcomes as natural frequencies. Figures are representative; the direction of effect is given where precise numbers are uncertain.

Apply & Test

Copy-paste chart notes that map to the real decisions in this chapter.

Template 1 — Chronic dysfunction workup note

• Trajectory: creatinine trend; proteinuria; time since transplant ___.
• Biopsy: IFTA grade; transplant glomerulopathy; hyalinosis; SV40 ___.
• Serology/virology: DSA ___; BK ___; PLA2R ___; complement ___.
• Specific diagnosis: chronic AMR / recurrence / CNI toxicity / BK / de novo / IFTA-only.
• Reversible cause present? yes/no — directed plan ___.

Template 2 — Recurrence / directed-treatment note

• Original disease and recurrence confirmed: ___.
• Directed therapy: PLEX (FSGS) / rituximab (membranous) / complement inhibitor (aHUS) / IS reduction (BK) / CNI minimisation.
• Response marker (proteinuria, PLA2R, viral load): ___.
• General CKD management: BP, RAAS, cardiovascular risk ___.
• Failing-graft planning (re-listing / dialysis): ___.

Pre-rounds compression. Rules only.

Active recall. At least one card per objective.

Micro-teaching for rounds. Two scenarios, five steps each.

Metacognition anchored to this chapter's tensions. No answers provided.

1. 1. A nonspecific scar is an easy place to stop looking; what keeps you biopsying the slowly failing graft rather than labelling and moving on?
2. 2. Most chronic injury is irreversible, but a few causes are not; how do you keep the rare treatable diagnosis in mind without over-investigating everyone?
3. 3. Counselling a patient whose original disease has recurred raises hard questions about re-transplant; how do you weigh another graft against the risk of another recurrence?
4. 4. Chronic active AMR is common, driven by non-adherence, and largely untreatable; how much of late graft loss is biology and how much is a failure of support?
5. 5. Reducing a nephrotoxic drug to save the graft can provoke rejection that loses it; how do you make that trade with incomplete information?

Nine items, each anchored in this chapter. At least one per objective.