The Case ∣ Hyperbicarbonatemia in a patient with Waldenstrom's macroglobulinemia. Pseudohyperbicarbonatemia due to paraproteinemia.

Division of Kidney Diseases and Hypertension, Department of Medicine, Hofstra North Shore Long Island Jewish School of Medicine, Great Neck, New York 11021, USA.
Kidney International (Impact Factor: 8.52). 03/2012; 81(6):603-5. DOI: 10.1038/ki.2011.427
Source: PubMed

ABSTRACT A 57-year-old Hispanic woman with a history of primary biliary cirrhosis and CREST syndrome presented with chief complaint of severe pain in the fingers and toes, progressively worsening for the past 3 months. Home medications included calcium and ergocalciferol. Review of systems was remarkable for right shoulder pain, as well as a 2-week history of black fingertip on the left second digit. Physical examination revealed no fever; the blood pressure was 155/80 mm/Hg, heart rate was 80 beats per minute, and respiratory rate was 18 breaths per minute. In addition, she had dry gangrene of the left second fingertip, and all distal digits were erythematous and cool to touch. She was treated with an anticoagulant and a calcium-channel blocker. Hospital treatment was complicated by positive blood cultures showing the growth of Haemophilus influenzae, which was treated with intravenous anti-biotics. Laboratory results are displayed in Table 1. Owing to a metabolic abnormality, which persisted across multiple repeated samples over days, a nephrology consult was requested.

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    ABSTRACT: Paraproteinemia, most often as a result of monoclonal gammopathy of unknown significance (MGUS), is very common and its prevalence is expected to increase with the aging of the population. Paraproteins can be associated with a variety of laboratory abnormalities. These may occur as a result of the underlying disease process that causes paraproteinemia, or may result from the paraproteins affecting a physiologic function in vivo. Laboratory abnormalities may also occur artifactually as a result of interference by the paraproteins with a laboratory test in vitro. A wide variety of laboratory tests may be affected, including several commonly obtained tests such as blood counts, serum sodium, calcium, phosphorous, and high-density lipoprotein (HDL) cholesterol. There is poor correlation between the concentration or type of paraproteins and the likelihood of interference. Awareness of this possibility is important so as to avoid erroneous diagnostic conclusions or unnecessary testing.
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