Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1187 page)

   
Borderline results:
sweat chloride 40–60 mmol/L

   A positive test is defined by sweat chloride >60 mmol/L in sweat from both arms, provided that a minimum of 15 μL of sweat is obtained from each site.

   Use

   Standard test for the diagnosis of CF

   Interpretation

Increased In

   CF (see Table 16.71)

   Endocrine disorders (e.g., untreated adrenal insufficiency, hypothyroidism, vasopressin-resistant diabetes insipidus, familial hypoparathyroidism, pseudohypoaldosteronism)

   Metabolic disorders (e.g., malnutrition, glycogen storage disease type I, MPS I H [Hurler syndrome], MPS I S [Scheie syndrome], fucosidosis)

   GU disorders (e.g., Klinefelter syndrome, nephrosis)

   Allergic/immunologic disorders (e.g., hypogammaglobulinemia, prolonged infusion with prostaglandin E
₁
, atopic dermatitis)

   Neuropsychologic disorders (e.g., anorexia nervosa)

   Others (e.g., ectodermal dysplasia, G6PD deficiency)

TABLE 16–71. Sweat Values in Cystic Fibrosis (mEq/L)