Multiple myeloma and hyperammonemic encephalopathy: review of 27 cases

Clin Lymphoma Myeloma. 2008 Dec;8(6):363-9. doi: 10.3816/CLM.2008.n.054.


Hyperammonemic encephalopathy is a rarely reported complication of multiple myeloma (MM). We describe an illustrative case of hyperammonemia in the setting of an immunoglobulin (Ig) D-lambda MM, and perform a systematic review of the English-written literature. Our search yielded 26 more cases. Median age was 64 years, and 54% of patients were male. All presented with progressive impairment of their level of consciousness. Median ammonium concentration was 109 micromol/L (interquartile range, 73-149 micromol/L). Most were IgA type (10 cases), and there were 2 cases of IgD type. Most cases were aggressive or chemotherapy-resistant forms of MM. Eight patients were diagnosed with MM at the same time as the episode of hyperammonemia. Only 1 patient had signs of portal hypertension as a result of concomitant hyperdynamic heart failure. Determination of amino acid in 10 patients showed high levels of glycine, low levels of tyrosine, and a low Fischer ratio. Two patients did not receive chemotherapy and died. Twenty-two out of 25 patients who received chemotherapy against MM showed a decrease in ammonium blood concentration, and of those, 15 survived the episode (68%). Overall mortality was 44%. In conclusion, hyperammonemia is a severe complication of MM, associated with a high mortality. It should be considered in any patient with MM and a low level of consciousness. Chemotherapy directed against MM seems to be the most effective measure in order to achieve normal ammonium levels and clinical improvement.

Publication types

  • Case Reports
  • Review
  • Systematic Review

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Consciousness Disorders / etiology
  • Female
  • Humans
  • Hyperammonemia / complications*
  • Male
  • Middle Aged
  • Multiple Myeloma / complications*
  • Neurotoxicity Syndromes / complications*