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Test Name:
Iron, Urine, 24-Hour

• SBMF No:
  42226
• Performance Lab Name:
  Mayo Medical Laboratories
• Test Mnemonic:
  U IRON
• ABN:
  Required – Not FDA-Approved
• CPT Code:
  83540
• LOINC Code:
  19146-0
• Ref Lab Test No:
  8571
• Also Known As:
  Fe (Iron), Urine
• Spec Type:
  Urine, 24-hour
• Spec Container:
  Plastic container with tightly fitting lid (no preservative and no metal cap or glued insert in lid)
• Pref Vol:
  10.0 mL
• Min Vol:
  0.5 mL
• Spec Collect:
  To begin collection of timed specimen, have patient urinate, noting date and exact time
  Discard this first portion of urine, but document date and time of voiding on container label and test requisition as "start" of timed specimen
  Save all urine voided during designated time period, including portion voided at exact end of time period
  IMPORTANT: Refrigerate entire specimen (2-8°C) during and after collection to prevent bacterial growth
  Document date and time of final voiding on label and requisition as "end" of timed specimen
• Spec Process:
  Upon completion of collection, mix entire specimen well and measure 24-hour volume
  Pour off 10.0 mL of urine into separate plastic tube(s)
  Refrigerate urine aliquot and transport refrigerated
  Send urine aliquot with notation of entire 24-hour urine volume on aliquot label and on requisition
• Spec Store Transport:
  Refrigerated
• Spec Remarks:
  High concentrations of gadolinium and iodine are known to interfere with most metals tests. If gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
• Methodology:
  Inductively coupled plasma-optical emission spectrometry (ICP-OES)
• Use:
  Diagnosis of hemochromatosis, hemolytic anemia, paroxysmal nocturnal hemoglobinemia, and impaired biliary clearance
• Clinical Significance:
  Iron is an essential element, serving as an enzyme cofactor and to facilitate oxygen transport. Iron is cleared primarily by biliary excretion via the feces and secondarily by renal clearance, which is a relatively minor route of clearance. Excessive accumulation of iron in iron-overload diseases leads to higher than normal urine concentration of iron, known as hemosiderinuria.
• Reference Range:
  

  0-15 years: Not established
  16 years and older: 100-300 mcg/specimen

  Interpretation:
  Normal excretion of iron occurs at the rate of approximately 100 mcg/day to 300 mcg/day. In the event that dietary iron is below minimum daily requirements (less than 2 mg/day in females, less than 1 mg/day in males), urinary excretion will be less than normal.

  Urinary iron is greater than normal in iron overload. It is not uncommon to observe iron excretion greater than 20,000 mcg/day in a patient with clinically evident hemochromatosis. Daily urine output of iron ranging from 500 mcg to 5,000 mcg suggests active hemolytic anemia, early-stage hemochromatosis, or impaired biliary clearance.

  Because iron elimination undergoes extreme diurnal variation (serum levels 10 times higher in a.m. than p.m.), collection of random specimens can cause very misleading interpretation.

• Additional Test Info:
  This test was developed and its performance characteristics determined by Laboratory Medicine and Pathology, Mayo Clinic. This test has not been cleared or approved by the U.S. Food and Drug Administration.
• Day Run:
  Mon, Wed
• Time Run:
  5:00 pm
• Time Reported:
  2-7 days
• Test Type:
  CHEMISTRY