Stacy E. F. Melanson

All articles by Stacy E. F. Melanson

Differential Diagnosis Low value for von Willebrand factor (vWF) and/or ristocetin cofactor (RCoF) or values in the low end of these normal ranges with a history of mild bleeding affecting males and females in the family suggest von Willebrand disease (vWD). vWD could be type 1, 2A, 2B, 2M, 2N, or 3. Continue Reading A…

Differential Diagnosis Hyperventilation in response to hypoxemia from a variety of causes Hyperventilation without hypoxemia as a stimulus, as in anxiety and CNS disorders that increase the respiratory rate Continue Reading Suggested Additional Lab Testing Follow arterial pH, pco2, and h2co3 as the disorder worsens or resolves.

Differential Diagnosis Neuromuscular disorders that decrease breathing, as produced by brain stem injury, myasthenia gravis, and poliomyelitis If sufficiently severe, multiple non-neuromuscular causes of impaired ventilation, perfusion, or gas diffusion produced by embolism, infection, selected cancers, asthma, bronchitis, and emphysema. Continue Reading Suggested Additional Lab Testing Serial blood gases to assess arterial pH, arterial pco2…

Differential Diagnosis Hepatitis C virus infection False-positive serologic test for hepatitis C Continue Reading Suggested Additional Lab Testing Acute hepatitis C Elevated liver function tests are expected with positive tests for anti-HCV by a variety of methods. Result may not become positive until 12-16 weeks after exposure. Patients are typically positive for HCV RNA within…

Differential Diagnosis Hepatitis B virus infection False-positive serologic test for hepatitis B virus Continue Reading Suggested Additional Lab Testing Acute hepatitis B Patient is positive for IgM antibody to HBV core antigen. Patient is usually positive for hepatitis B surface antigen and hepatitis B virus e antigen. Presence of the e antigen indicates a high…

Differential Diagnosis Gastric ulcer Duodenal ulcer Continue Reading Suggested Additional Lab Testing For gastric ulcer: Endoscopy to visualize the ulcer; biopsy of the lesion is recommended to determine if patient has gastric adenocarcinoma. Rapid urease test of biopsy material (CLO test) verifies the presence of active infection. For duodenal ulcer disease: Urea breath test is…

Differential Diagnosis Patient has an HIV infection. Screening test is a false-positive; there is no HIV infection. Continue Reading Suggested Additional Lab Testing Western blot Most important test for patient with a positive HIV screening test Will determine if patient has antibodies to specific HIV-associated proteins Will confirm or refute a diagnosis of HIV infection.…

Differential Diagnosis Systemic lupus erythematosus (SLE): when active, usually a homogenous pattern on ANA or less commonly speckled, rim, or nucleolar when present in high enough titer to be clinically significant Sjögren syndrome: common ANA pattern is speckled; less commonly homogenous Continue Reading Scleroderma or systemic sclerosis: ANA pattern is most commonly speckled, followed by…

Differential Diagnosis Multiple myeloma Waldenstrom macroglobulinemia Continue Reading Monoclonal gammopathy of unknown significance (MGUS) Low concentration of monoclonal immunoglobulins (LCMI) Heavy chain disease Suggested Additional Lab Testing For multiple myeloma: In addition to SPEP followed by immunofixation, quantitative serum immunoglobulin should be performed, because the M component must be greater than3 g/dL in the serum.…