Intern Report 1/25/18 – Chronic diarrhea due to Secondary Amyloid from Multiple Myeloma

Thank you, John, for presenting a case of a middle-aged woman with significant weight loss and chronic diarrhea.

Key Pearls:

  1. Initial approach to diarrhea often involves determining first duration of symptoms (acute vs. chronic) and then assessing whether the quality of the diarrhea (inflammatory vs. non-inflammatory). Inflammatory diarrhea, in addition to being accompanied by systemic symptoms, may be bloody and include elevated stool calprotectin, stool WBCs, or stool lactoferrin.
  2. Consider multiple myeloma when you start to see evidence of the CRAB criteriaCalcium elevation, Renal injury, Anemia, and Boney pain.
  3. The overlap between MM and chronic diarrhea can be through amyloid! Up to 10% of patients with MM may have amyloidosis as a secondary complication. Patients with amyloidosis who have MM have a worse prognosis than those who do not.

Break down of diarrhea based on duration of symptoms and inflammatory vs. non-inflammatory causes (courtesy of prior blog post from Rabih that’s full of diarrhea info!)

diarrhea

Multiple Myeloma and Amyloid

  • HH Pearl: Up to 10% of patients with MM may have AL amyloidosis as a secondary complication. The two conditions are often diagnosed around the same time. Occasionally though, the development of full-on MM can lag behind the clinical diagnosis of amyloid by 6 months!
  • Amyloid can occur in other plasma cell dyscrasias as well, such as Waldenström macroglobulinemia.
  • Patients with amyloidosis who have MM have a worse prognosis than those who do not.
    • In a retrospective analysis of 147 patients with biopsy-proven AL amyloidosis who also had specialized testing for determination of circulating plasma cells, 20 patients had concurrent MM.
    • Patients with both AL amyloidosis and MM had a significantly worse prognosis than those with AL amyloidosis alone (14 versus 32 months).

 

 

How does myeloma affect the kidney? There is a huge list but here are the main mechanisms (from prior Kevin Duan blogpost!)

  • Myeloma cast nephropathy: all those proteins collect as casts and can cause tubular injury (remember that Tamm-Horsfall thing?)
  • Amyloidosis: increased AL amyloid production takes place in mesangial cells causing damage to the glomerulus
  • Immunoglobulin deposition disease: similar mechanism of damage to amyloid, where immunoglobulin deposits in the glomerulus
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