# Cardiac-Predominant AL: The Missing Proteinuria Trap

Neither absent nephrotic syndrome nor a preserved ejection fraction safely closes the case. Seek a unifying explanation for the entire phenotype.

![Infographic: Cardiac-Predominant AL: The Missing Proteinuria Trap](https://urinenephrology.org/visual-reference/images/mastery-cardiac-al.png?v=20261003c)

## Organs vary in expression

AL amyloidosis can present mainly through cardiac dysfunction. Limited proteinuria or a nondiagnostic echocardiographic feature does not exclude clinically significant disease.

## Identify a mismatch

Unexplained heart failure, restrictive physiology, low blood pressure, or multisystem symptoms should prompt reconsideration when ordinary explanations do not fit.

## Screen beyond a single M-spike

Order serum free light chains and serum plus urine immunofixation when cardiac AL is plausible. A negative serum electrophoresis alone does not close the case. Interpret abnormal results with renal function and pursue tissue confirmation and amyloid typing through the specialist pathway.

## Reconcile EF with forward flow

EF is stroke volume divided by end-diastolic volume. A small stiff ventricle can eject a normal fraction of an abnormally small filling volume. Review stroke volume, filling pressures, perfusion, and restrictive features when hypotension or oliguria conflicts with a preserved EF.

## Coordinate early

A suspected plasma-cell disorder with cardiac involvement warrants prompt specialist assessment. Treatment tolerance and organ risk matter alongside clonal burden.

## Preserve diagnostic humility

Neither absent nephrotic syndrome nor a preserved ejection fraction safely closes the case. Seek a unifying explanation for the entire phenotype.

## Supporting evidence

- [Supporting guideline or source](https://www.acc.org/latest-in-cardiology/ten-points-to-remember/2023/01/19/14/49/2023-acc-consensus-on-cardiac-amyloidosis)

## Source lessons

- [cardiac predominant](https://urinenephrology.org/mastery/amyloid-series/cardiac-predominant.html)
- [misleading echo](https://urinenephrology.org/mastery/amyloid-series/misleading-echo.html)
- [cardiac amyloidosis diagnosis](https://urinenephrology.org/mastery/paraprotein/cardiac-amyloidosis-diagnosis.html)

Read alongside the full lessons; the findings and decisions shown here require the stated clinical context.