Updated: 3/4/2019

Lyme Disease

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Snapshot
  • A 16-year-old boy presents to his primary care physician with fatigue, malaise, and a rash. His symptoms began approximately 1 week ago and have progressively worsened. He said he recently hiked in northern Connecticut but is unsure if he was bitten by a tick. On physical exam, there is an erythematous and slightly raised lesion that appears "target-like" on the right thigh. He is given oral doxycycline.
Introduction
  • Definition
    • a tick-borne illness characterized by 3 stages
      • early localized stage (within 1 month of the tick bite)
        • erythema migrans
      • early disseminated stage
        • multiple erythema migrans
        • neurological symptoms (e.g., facial nerve palsy, meningitis, and mononeuritis multiplex)
        • cardiac symptoms (e.g., carditis)
      • late stage
        • arthritis
        • encephalopathy or polyneuropathy
  • Epidemiology
    • incidence
      • most cases in the northeast and upper midwest
  • Etiology
    • Borrelia burgdorferi, a spirochete transmitted by the Ixodes tick
      • this tick is also a vector for
        • Anaplasma spp.
        • Babesia microti
  • Prognosis
    • the rash typically self-resolves without treatment
    • untreated Lyme disease can result in arthritis
    • excellent prognosis with early antibiotic treatment 
Presentation
  • Symptoms
    • early localized stage
      • erythema migrans (7-14 days post-tick bite)
        • round erythema that expands and can result in the classic target lesion
        • may be accompanied by systemic symptoms such as
          • fevers
          • myalgias
          • arthralgias
          • headache
          • fatigue
    • early disseminated stage
      • multiple erythema migrans
      • neurological symptoms (e.g., facial nerve palsy, meningitis, and mononeuritis multiplex)
      • lyme carditis
        • may present as an atrioventricular block and/or myopericarditis
    • late stage
      • arthritis
        • the knees are classically involved
      • encephalopathy or polyneuropathy
Differential Diagnosis
  • Ehrlichiosis 
    • fever, malaise, aches, without a rash
    • leukopenia, thrombocytopenia and elevated aminotransferases
Studies
  • Making the diagnosis
    • this is a clinical diagnosis
  • Cerebrospinal fluid analysis when there is central nervous system involvement
  • Synovial fluid analysis when arthritis is suspected
  • Serologic studies
    • performed to support the clinical diagnosis 
Treatment
  • Medical
    • doxycycline or amoxicillin  
      • indication
        • erythema migrans
        • Lyme arthritis
      • macrolides can be used in patients who are allergic to doxycycline, ceftriaxone, and cefuroxime 
    • ceftriaxone
      • indication
        • neurologic Lyme disease
        • Lyme carditis
 

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Questions (4)
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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(M2.ID.4686) A 29-year-old male presents to an urgent care clinic with complaints of fever, malaise, fatigue, and a rash on his upper arm (Figure A). He reports that he just returned from a camping trip in Connecticut this past weekend. Which of the following is a known complication of failing to appropriately treat this patient's presenting condition? Review Topic

QID: 107418
FIGURES:
1

Toxic megacolon

0%

(0/19)

2

Flaccid paralysis

5%

(1/19)

3

Hydrophobia

0%

(0/19)

4

Cranial nerve VII palsy

89%

(17/19)

5

Paralytic myelitis

0%

(0/19)

M2

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