Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (794 page)

   Hypoglycemia

   Hypotension

   Hypothyroidism

   DKA

   Neuroblastoma

   Paragangliomas

   Pheochromocytoma

Decreased In

   Norepinephrine: anorexia nervosa

   Autonomous nervous system dysfunction

   Orthostatic hypotension

   Dopamine: possibly decreased in Parkinson disease

   Limitations

   Most assays measure only free catecholamines, but a few measure both free and conjugated types. Free amines are more closely associated with tumor load than conjugated ones.

   Physiologic stimuli, drugs, or improper specimen collection slightly increases the levels. Patients should not eat, use tobacco, or drink caffeinated beverages for at least 4 hours before collection. Measurement of plasma or urine fractionated metanephrines provides better diagnostic sensitivity than measurement of catecholamines.