Lab

Sweat Chloride

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Sweat Chloride, Sweat Test

  • See Also
  1. Delta F508
  • Indication
  1. Cystic Fibrosis testing
  • Method
  1. Quantitative Pilocarpine Iontophoresis
    1. Stimulates local sweat production (parasympathetic)
    2. Collect sweat on gauze pads
    3. Analyze Sodium and chloride content
  2. Minimum sweat amount required: 50 mg (200 mg better)
  • Normal
  1. Sweat contains <60 meq/Liter Chloride and Sodium
  • Abnormal Results
  1. CF Sweat contains > 70 meq/L Chloride and Sodium
  2. Error: >30 meq/L difference between chloride and Sodium
  • Indications to repeat the test for confirmation
  1. Positive Test
  2. Suspected False Negative
  • False Positive Tests
  1. Glucose 6 Phosphate Dehydrogenase deficiency (G6PD)
  2. Hypothyroidism
  3. Glycogen Storage Disease
  4. Untreated Adrenal Insufficiency
  5. Malnutrition
  • Reference
  1. Bakerman (1984) ABC's of Lab Data, ILD, Greenville, NC