Consult Rounds: Cryoglobulins and the Kidney

Cryoglobulins and the Kidney

Cryoglobulins are Igs that reversibilly precipitate at temperatures <37C.  This results in symptoms that can lead to rashes, vasculitis, ulcers, ischemia, joint pains, and eventually in 25% cases – renal injury.

Two mechanisms: immune complex GN vs high viscosity related.  All have nephritic/nephrotic syndrome with various levels of kidney function.

1/3 with purpura and arthralgia
¾ with low C4 and ½ with low C3

All 3 types of cryoglobulins reported with renal disease

Most commonly it occurs in settings of type II (“mixed”) cryo secondary to hepatitis C virus.  Most patients with type II or III cryoglobulins have a positive rheumatoid factor.  The pathology pattern of injury is either membranoproliferative or diffuse proliferative GN.

•          Type 1 Cryo( monoclonal IgM or IgG) – MM, MGUS, WM, lymphomas and CLL

•          Type 2 Cryo(monoclonal IgM + polyclonal IgG)- CLL, lymphoma, SLE, Hep C

•          Type 3 Cryo(polyclonal)- lymphoproliferative diseases, SLE

Treatment

Treatment of underlying cause- Hep, SLE, Myeloma

Steroids

Alkylating Agents

Anti CD-20 agents( good response in some cases)

Plasmapheresis ( adjunct) if skin involved and early renal
involvement

Topic Discussion: Baclofen and ESRD

Baclofen is often used as a muscle relaxant in many patients. It has a half life of 3-7 hours and 80% excreted by the kidneys.  It is extremely important to dose adjust in CKD and avoid use in ESRD patients. Dialysis is a good mechanism to remove the agent as well in-case of ingestions and overdoses.

A recent case published in AJKD highlights this important drug related interaction in CKD and ESRD patients. 

The authors describe two excellent clinical algorithms.

The first algorithm discusses dose adjustments.
If GFR>90, no dose adjustment necessary
If GFR 60-90, decrease initial dose by 1/3
If GFR 30-60, decrease dose by ½ and watch for mental status changes
If on RRT or GFR<30, avoid use

The second algorithm discusses if there is a known baclofen toxicity( seizures, hypotenia, encephalopathy, etc.)

If severe AKI, CKD or ESRD- start daily HD or CRRT
If normal renal function or mild AKI but with respiratory depression or seizures- start daily HD or CRRT
If normal renal function or mild AKI and no severe symptoms- no dialysis