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Snapshot
  • A 60-year-old healthy man undergoes a screening colonoscopy. He has been staying active, does not smoke, denies any bloody or dark stools, changes in stool, abdominal pain, or fatigue.  His prior colonoscopy was normal.  During today’s colonoscopy, his gastroenterologist notes a small pedunculated growth in the descending colon.
Introduction
  • Overview
    • abnormal growth of tissue from the colonic mucosa
      • most are benign but some can progress to cancer
      • treatment is resection  
    • can be part of a polyposis syndrome
      • familial adenomatous polyposis
      • juvenile polyposis syndrome
      • Peutz-Jeghers syndrome
      • Gardner syndrome
  • Epidemiology
    • incidence
      • highly prevalent (30-50% of adults)
      • 90% occur after 50 years of age
      • can be hyperplastic and benign or adenomatous with malignant transformation
        • up to 90% are hyperplastic polyps
      • most commonly in sigmoid and rectum
    • risk factors
      • smoking
      • obesity
      • high-fat diet
      • red meat
  • Pathogenesis
    • pathophysiology
      • hyperplastic polyp
        • non-dysplastic proliferation of the colonic epithelium
      • adenomatous polyp
        • growth and malignant transformation with genetic mutations
        • can be tubular, tubulovillous, villous, or sessile serrated
          • villous has the greatest malignant potential
  • Genetics
    • APC
    • KRAS
    • T53
    • BRAF
    • microsatellite instability
    • mismatch repair
  • Prognosis
    • natural history
      • malignant progression of adenomatous polyps can take years
    • good progosis with polypectomy
Presentation
  • Symptoms
    • most often asymptomatic
    • common symptoms
      • rectal bleeding
      • change in stool caliber
  • Physical exam
    • inspection
      • endoscopically visualized
    • provocative tests
      • digital rectal exam
        • occult blood
        • palpated if distal
Imaging
  • Lower gastrointestinal radiograph series
    • may detect larger polyps
  • Virtual colonoscopy with computed tomography scan
    • limited use outside of research
    • may detect larger polyps
    • poor sensitivity
Studies
  • Serum labs
    • tumor markers
      • CEA
      • CA19-9
      • associated but not used for screening or diagnosis
  • Invasive studies
    • stool occult blood test
      • neither sensitive nor specific
    • endoscopic evaluation
      • colonoscopy is the best evaluation
      • alternatives include flexible sigmoidoscopy or pill capsule endoscopy
      • obtain a biopsy for pathological evaluation
  • Histology
    • H&E of endoscopic biopsy samples is diagnostic
      • type of polyp
      • size
      • degree of dysplasia
Differential
  • Inflammatory bowel disease
    • key distinguishing factor
      • pseudopolyp from the scarring process in response to inflammation
  • Familial adenomatous polyposis
    • key distinguishing factors
      • many polyps
      • younger age
  • Peutz-Jeghers syndrome
    • key distinguishing factors
      • hamartomatous polyps
      • mucocutaneous hyperpigmentation
Treatment
  • Surgical
    • endoscopic polypectomy
      • indications
        • for all visualized polyps
    • colectomy
      • indications
        • endoscopically unresectable polyps
        • multiple large adenomas
        • high-grade dysplasia
        • invasive adenocarcinoma
        • severe gastrointestinal bleeding
Complications
  • Gastrointestinal bleeding
  • Adenocarcinoma of the colon
    • risk factors
      • time undetected
    • treatment
      • depends on stage
 

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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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