Updated: 12/15/2019

Interstitial Lung Disease

Review Topic
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2 2
  • A 68-year-old man presents to the emergency department for worsening shortness of breath. His dyspnea was most notable with exertion; however, over the course of the past several months, it presented at rest. He reports that he has a non-productive cough and denies have any sinus pain, fever, malaise, chills, or night sweats. He has a past medical history of hypertension and hyperlipidemia. He is a retired aircraft mechanic and has smoked 1 pack of cigarettes daily for the past 45 years. His temperature is 98.6°F (37°C), blood pressure is 134/90 mmHg, pulse is 106/min, respirations are 23/min, and oxygen saturation is 88% on room air. On physical exam, the patient is alert to person but not place or time. There are rales on pulmonary auscultation and digital clubbing. A chest radiograph demonstrates a reticular pattern and honeycombing. 
  • Definition
    • inflammatory lung process that leads to alveolar wall thickening, impairing gas exchange
  • Etiology
    • environmental
      • coal worker pneumoconiosis
      • silicosis
      • asbestosis 
        • associated with roofing work, navy shipyard work
        • associated with pleural plaques on chest imaging
        • may see ferruginous bodies on histology
          • asbestos fibers coated with iron and calcium
      • berylliosis
    • granulomatous disease
      • sarcoidosis
      • granulomatosis with polyangiitis
      • eosinophillic granulomatosis with polyangiitis
      • histiocytosis x
    • alveolar filling disease
      • Goodpasture syndrome
      • alveolar proteinosis
      • pulmonary hemosiderosis
    • hypersensitivity lung disease
      • eosinophilic pneumonitis
      • hypersensitivity pneumonitis
    • drugs
      • amiodarone
      • bleomycin
      • phenytoin
  • Pathogenesis
    • distal airspace tissue injury (due to a myriad of causes) leads to abnormal wound healing
      • causes structural remodeling, where collagenous fibrosis ensues, impairing gas exchange
  • Prognosis
    • variable and depends on the underlying cause
  • Symptoms and physical exam findings differ depending on the underlying cause; for example, patients with pulmonary sarcoidosis may have erythema nodosum
  • Symptoms
    • dyspnea (initially with exertion and as the disease progresses, then at rest)
    • cough
    • fatigue
  • Physical exam
    • rales on pulmonary auscultation
    • digital clubbing
    • cyanosis in advanced disease
  • Chest radiography
    • indication
      • typically initial imaging option in the workup of interstitial lung disease
    • findings
      • reticular pattern
      • honeycombing
  • High-resolution CT scan of the chest
    • indication
      • diagnostic and helps narrow the cause of interstitial lung disease
  • Pulmonary function tests 
    • indication
      • obtained in virtually all patients with interstitial lung disease
        • aids in assessing severity of lung disease and determines whether there is an obstructive, restrictive, or mixed lung patter
  • Heart failure
    • differentiating factors
      • patients may have peripheral edema and hemoptysis 
  • Pulmonary embolism
    • differentiating factors
      • patients will have a filling defect on CT angiogram of the chest
  • Of note, treatment is dependent upon the underlying cause
  • Conservative
    • smoking cessation and influenza and pneumococcal vaccines
      • indication
        • should be given to all patients with interstitial lung disease, unless contraindicated
  • Medical
    • intravenous corticosteroids
      • indication
        • first-line therapy for patients for acute respiratory therapy 
    • intravenous cyclophosphamide
      • indication
        • second-line therapy for patients for acute respiratory therapy
  • Irreversible pulmonary fibrosis
  • Respiratory failure



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Questions (2)
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
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
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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(M2.PL.17.4867) A 57-year-old man presents to his primary care physician with shortness of breath. The patient has had worsening shortness of breath for the past year. He has a past medical history of asthma and constipation. His current medications include albuterol and sodium docusate. The patient was an officer in the navy and currently lives at home with his wife. He has a 52 pack-year smoking history. Pulmonary function testing is performed at this visit as revealed in Figure A. The results of this test at this visit are revealed by the blue loop, as compared to his results 12 years ago as seen in the green dotted loop of Figure A. Which of the following is a possible diagnosis for this patient's presentation? Review Topic | Tested Concept

QID: 109613

Chronic obstructive pulmonary disease




Unstable angina




Interstitial lung disease




Poorly treated asthma




Small cell carcinoma of the lung



L 2 D

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