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  • A 36-year-old man presents to an emergency room in Colorado for shortness of breath. He reports that he works as an exterminator and is often exposed to cockroaches, rodents, and mold. He reports having a flu-like cold a week ago with fevers, chills, muscle aches, and fatigue. A few days ago, he started having a nonproductive cough and shortness of breath even without exertion. His past medical history includes hypertension and hyperlipidemia. On physical exam, there are diffuse rales on bilateral lung fields and decreased breath sounds in the bases. Chest radiograph shows centrally-distributed pulmonary infiltrates, bilateral pleural effusions, and blurred pericardiac border. He is admitted for further management. (Hantavirus pulmonary syndrome)
Introduction
  • Classification
    • hantavirus
      • an enveloped, segmented, circular, negative-sense RNA zoonotic virus with helical capsid
      • a bunyavirus
      • transmission via inhalation of aerosolized rodent excretions or saliva
      • clinical syndromes
        • hantavirus pulmonary syndrome (HPS)
          • “Sin Nombre” virus is most common cause
        • hemorrhagic fever with renal failure syndrome (HFRS)
  • Epidemiology
    • incidence
      • South America
      • Southwest US
    • risk factors
      • residence or travel in rural areas
      • exposure to rodents
  • Pathogenesis
    • the virus causes inflammation, increased vascular permeability, and endothelial damage resulting in massive capillary leak syndrome
  • Prognosis
    • HPS
      • mortality rate is 30-40%
    • HFRS
      • 3-15%
Presentation
  • HPS
    • initial flu-like prodrome lasts 3-6 days
      • fevers and chills
      • fatigue, malaise, and myalgias
      • nausea, vomiting, and diarrhea
    • subsequent pulmonary edema and shock
      • nonproductive cough
      • tachypnea
      • hypoxia
      • diffuse rales due to pulmonary edema
  • HFRS
    • fever
      • with headaches, chills, blurred vision, and myalgias
    • hemorrhage
      • petechiae in axilla or soft palate
      • subconjunctival hemorrhage
    • renal insufficiency
      • oliguria followed by diuresis phase
Imaging
  • Chest radiography
    • indication
      • all patients with HPS
    • findings
      • pleural effusions
      • central pulmonary infiltrates
      • pericardiac haziness (shaggy or fuzzy heart sign)
        • characteristic of HPS
      • no cardiomegaly
Studies
  • Labs
    • detection of viral RNA via reverse transcriptase-polymerase chain reaction (RT-PCR)
    • detection of Hantavirus-specific immunoglobulin M and G with enzyme-linked immunosorbent assay (ELISA)
    • HPS 
      • ↑ creatine kinase
      • ↓ serum albumin level
    • HFRS
      • ↑ BUN and creatinine
      • ↓ C3
      • hematuria
      • proteinuria
  • Making the diagnosis
    • based on clinical presentation and laboratory studies
      • patients with acute onset respiratory distress and decreased albumin should prompt suspicion of HPS
Differential
  • Cardiac pulmonary edema
    • distinguishing factor
      • typically have notable cardiac findings including S3 gallop and cardiomegaly
  • Acute respiratory distress syndrome
    • distinguishing factor
      • chest radiograph usually shows peripheral infiltrates and less likely to have pleural effusions
Treatment
  • Management approach
    • mainstay of treatment is supportive care
  • Conservative
    • supportive care
      • indication
        • all patients
      • modalities
        • intravenous hydration
        • hemodynamic and respiratory support
Complications
  • Acute tubular necrosis
 

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Questions (1)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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