Michael Laposata

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. A person with…

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 Suggested Additional Lab Testing Follow arterial pH, pco2, and h2co3 as the disorder worsens or resolves.Related Content

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. Suggested Additional Lab Testing Serial blood gases to assess arterial pH, arterial pco2 and arterial…

Differential Diagnosis Hepatitis C virus infection False-positive serologic test for hepatitis C Suggested Additional Lab Testing Acute hepatitis CRelated Content 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 4…

Differential Diagnosis Hepatitis B virus infection False-positive serologic test for hepatitis B virus Suggested Additional Lab Testing Acute hepatitis BRelated Content 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 degree…

Differential Diagnosis Hepatitis A virus infection False-positive serologic test for hepatitis A Suggested Additional Lab Testing For acute hepatitis A:Related Content Elevated liver function tests for the aminotransferase Positive test for anti-HAV IgM Anti-HAV IgM levels usually remain elevated for 3-6 months.

Differential Diagnosis Gastric ulcer Duodenal ulcer Suggested Additional Lab Testing For gastric ulcer:Related Content 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 a…

Differential Diagnosis Patient has an HIV infection. Screening test is a false-positive; there is no HIV infection. Suggested Additional Lab Testing Western blotRelated Content 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. CD4…

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 Scleroderma or systemic sclerosis: ANA pattern is most commonly speckled, followed by centromeric and…

Differential Diagnosis Multiple myeloma Waldenstrom macroglobulinemia Monoclonal gammopathy of unknown significance (MGUS)Related Content 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. Bone…

Differential Diagnosis Vomiting or nasogastric suction Ingestion of certain drugs, such as diuretics Numerous endocrine disorders, including Cushing syndrome and hypoparathyroidismRelated Content Suggested Additional Lab Testing Serial blood gases to assess arterial pH, arterial h2co3 and arterial pco2 are important when the disease is evolving or resolving. Tests relevant to the diagnosis of Cushing syndrome…

Differential Diagnosis Uncontrolled diabetes Renal failure from a variety of causes Tissue hypoxiaRelated Content GI h2co3 loss from diarrhea Methanol intoxication Suggested Additional Lab Testing Urinary ketones might be valuable to show increased ketoacids in uncontrolled diabetes. Urinary changes that show impaired hydrogen excretion suggest renal failure. Increased lactic acid in the blood is suggestive…

Differential Diagnosis Graves disease Toxic multinodular goiter Toxic adenomaRelated Content Subacute thyroiditis Chronic thyroiditis Suggested Additional Lab Testing Graves disease: T4 is high and in some cases T3 is elevated and T4 is normal. Toxic multinodular goiter: T4 and T3 are high with suggestive radioactive iodine uptake and thyroid scans. Toxic adenoma: T4 and T3…

Differential Diagnosis Increase in extracellular fluid volume as produced by congestive heart failure, cirrhosis and ascites, producing dilutional hyponatremia GI loss of sodium from vomiting, diarrhea, or malabsorption, especially with replacement of fluid and not electrolytes Renal sodium loss from diuretic use or chronic renal insufficiencyRelated Content Addison’s disease producing adrenal insufficiency Syndrome of inappropriate…

Differential Diagnosis Treatment with drugs Loop or thiazide diuretics Mineralocorticoids such as aldosterone and corticosterone Antibiotics such as carbenicillin and ticarcillinRelated Content GI losses of potassium from vomiting, diarrhea, malabsorption Hyperaldosteronism Aldosteronism may be primary or secondary, as in renal artery stenosis. Endogenous or exogenous increase in corticosteroids from Cushing syndrome or dietary or parenteral…

Differential Diagnosis Reactive hypoglycemia is usually observed in diabetics but also is found in nondiabetics following ingestion of a high-carbohydrate meal. Pts w/ hypoglycemia caused by an insulin-producing tumor may have signs & symptoms associated w/ malignancy. For surreptitious insulin injection, seek a history of insulin use or access to insulin.Related Content For excess administration…

Differential Diagnosis Primary adrenal insufficiency Secondary adrenal insufficiency with underlying disorder Suggested Additional Lab Testing Primary adrenal insufficiencyRelated Content Exogenous ACTH does not stimulate cortisol secretion, and the plasma ACTH is elevated. Serum aldosterone is low in cases in which destruction of the adrenal gland affects both cortisol and aldosterone production. Testing for antibodies against…

Differential Diagnosis Decreased exposure to sunlight, milk allergies, and adherence to a strict vegetarian diet can lead to vitamin D deficiency. Vitamin D deficiency state or abnormal metabolism of vitamin D: A deficiency can also occur from malabsorption of vitamin D.Related Content Abnormal metabolism of vitamin D, ultimately to 1,25-dihydroxy vitamin D, is found most…

Differential Diagnosis Chronic bronchitis Emphysema AsthmaRelated Content Pneumoconioses Central or peripheral neuromuscular disorders Right-to-left shunts of great vessels Pulmonary embolism and pulmonary infarction Sarcoidosis Selected lung cancers Suggested Additional Lab Testing If there is a need to monitor blood gases, pCO and blood pH would be useful. In most of these circumstances, the testing is…

Differential Diagnosis Iron deficiency anemia Thalassemia Anemia of chronic disease Acute blood loss Lead poisoningRelated Content Anemia from folate or vitamin B12 deficiency Sickle cell anemia Hereditary spherocytosis or elliptocytosis Hemoglobinopathies other than sickle cell disease Autoimmune hemolytic anemia Hemolytic disease of the newborn Microangiopathic hemolytic anemia Glucose-6-phosphate dehydrogenase (GGPD) deficiency Pyruvate kinase deficiency Paroxysmal…

Differential Diagnosis Diabetic ketoacidosis (DKA) Starvation Suggested Additional Lab Testing Anion gap is commonly measured in patients with DKA.Related Content Management of DKA involves serial measurements of electrolytes, glucose, and blood gases in the acute setting to follow clinical progress. Clinical Considerations History of diabetes in a patient who presents with ketonuria and appropriate signs…

Differential Diagnosis Increased INR, Coumadin over-dosage; low INR, inadequate Coumadin dosage Clinical conditions that increase Coumadin effect and elevate INR include: HyperthyroidismRelated Content Low vitamin K intake Poor nutritional state Diarrhea Liver disease Congestive heart failure Cancer Connective tissue diseases High fever Conditions known to decrease Coumadin effect and decrease INR include: Hypothyroidism High vitamin…

Differential Diagnosis Glomerular membrane damage Impaired tubular reabsorption of protein Multiple myelomaRelated Content Preeclampsia Diabetic nephropathy Suggested Additional Lab Testing Initial evaluation for renal function with serum or plasma BUN and/or creatinine If there is concern about an undiagnosed case of diabetes mellitus, evaluation for diabetes If there is concern about multiple myeloma, serum protein…

Differential Diagnosis Diabetes mellitus Impaired tubular reabsorption of glucose Pregnancy with latent diabetes mellitusRelated Content Suggested Additional Lab Testing Serum or plasma BUN and/or creatinine is useful to initially evaluate renal function. Evaluate for diabetes mellitus if not already done.

Differential Diagnosis Primary hyperaldosteronism Secondary hyperaldosteronism Suggested Additional Lab Testing Primary hyperaldosteronismRelated Content Serum potassium is usually low, but a low-sodium diet may result in a normal value. Serum sodium is mildly elevated in most cases. Plasma renin activity is low for most cases of hyperaldosteronism. The low value for plasma renin makes the ratio…

Differential Diagnosis Heparin in the specimen, which may be a result of heparin treatment of the patient Treatment with low molecular weight heparin, argatroban, or lepirudin A lupus anticoagulant (i.e., lupus inhibitor)Related Content Deficiency of factor VIII (hemophilia A) or IX (hemophilia B) Deficiency of factor VIII (mild or severe) associated with von Willebrand’s disease…

Differential Diagnosis Initiation of Coumadin therapy or a very low dose of Coumadin Inadequate intake of foods rich in vitamin K, such as cauliflower, broccoli, chick peas, other leafy vegetables A stimulus for disseminated intravascular coagulation (DIC)Related Content Evidence of liver disease from clinical or laboratory parameters Family history of bleeding that could be associated…

Differential Diagnosis Coumadin therapy in the therapeutic or supratherapeutic range Moderate to severe vitamin K deficiency Treatment with high doses of heparin or low molecular weight heparinRelated Content Treatment with direct thrombin inhibitors, such as hirudin or related compounds (i.e., lepirudin, refludan) or argatroban Moderate to severe DIC Moderate to severe liver disease A lupus…

Differential Diagnosis Cystitis Pyelonephritis SepsisRelated Content Suggested Additional Lab Testing Serum or plasma BUN and/or creatinine to assess general urinary function is suggested. White blood cell (WBC) count and differential may provide evidence of infection.

Differential Diagnosis DIC Thrombosis: can be venous with pulmonary embolism (PE) and/or deep vein thrombosis (DVT) or arterial, as caused by peripheral artery thrombosis, myocardial infarction, and stroke Pulmonary EmbolismRelated Content Infections Complications of pregnancy Malignancy Trauma Burns Suggested Additional Lab Testing D-dimer levels over the course of hours to days to determine if D-dimer…