Synonym

• Fe (Serum)
• Serum iron
• Iron level

Tubes

• Red or tiger top tube
• 7-10 mL of venous blood

Additional information

• Fasting for 10-12 hrs
• Handle sample gently to prevent hemolysis
• Send sample to lab immediately
• Avoid sleep deprivation and extreme stress before sample collection
• Sample is collected prior to the initiation of iron therapy, blood transfusion, or iron-chelating therapy
• If the patient has received a blood transfusion, delay iron testing for 4 days

Info

• The serum iron assay measures the amount of circulating iron bound to transferrin in the blood
• Iron is primarily required for hemoglobin synthesis, and is necessary for the proliferation and maturation of red blood cells (erythropoiesis)
• Iron is also required for proper muscle and organ function
• Iron is intestinally absorbed and circulates in the bloodstream bound to transferrin, a protein synthesized by the liver that regulates iron absorption
• About 65% of iron is bound to hemoglobin molecules, 4% is bound to myoglobin molecules, a small amount found in cellular enzymes, and the remainder stored as ferritin or hemosiderin in the liver, bone marrow, and spleen
• Commonly performed iron studies, to evaluate the body’s storage, utilization, and availability of iron, includes the serum iron test, the total iron-binding capacity (TIBC), and the transferrin saturation

Clinical

• The clinical utility of the serum iron assay includes:
• Evaluation of anemia and to distinguish between iron deficiency anemia and anemia of chronic disease
• Evaluation of thalassemia and sideroblastic anemia
• Evaluation of nutritional status by estimating total iron storage
• Determine the presence of disorders involving diminished protein synthesis or defects in iron absorption
• Determine decreased serum iron levels
• Aids in the diagnosis of hemochromatosis or other disorders of iron metabolism and storage
• Evaluation of iron poisoning
• Evaluation of iron overload in dialysis patients or patients with transfusion dependent anemia
• Monitor response to treatment for iron deficiency anemia
• Decreased iron levels, as seen in iron deficiency anemia, may clinically present as:
• Fatigue and weakness
• Pale skin
• Tachycardia
• Shortness of breath
• Chest pain
• Dizziness
• Syncope
• Cognitive problems
• Numbness or coldness of extremities
• Headache
• Inflammation or soreness of tongue
• Brittle nails
• Unusual cravings for non-nutritive substances, such as ice, dirt or pure starch
• Poor appetite in infants and children
• Iron poisoning usually presents (within 6 hrs after ingestion of excessive amount of iron) with:
• Severe vomiting
• Abdominal pain
• Bloody diarrhea
• Dehydration
• Cyanosis
• Convulsions
• Iron overload, as seen in hemochromatosis, presents with nonspecific symptoms at the early stage of the disease, which includes:
• Fatigue
• Weakness
• Weight loss
• Abdominal pain
• Joint pain
• Loss of menstrual periods or early menopause
• Loss of libido or impotence
• Loss of body hair
• Shortness of breath
• Advanced stages of hemochromatosis may affect the following areas resulting in:
• Heart: Cardiomyopathy, conduction disturbances
• Liver: Abdominal pain, elevated liver chemistries, hepatomegaly, cirrhosis, hepatocellular carcinoma
• Skin: Bronzing (melanin deposition), gray pigmentation (iron deposition)
• Infection: Vibrio vulnificus, Listeria monocytogenes, Pasteurella pseudotuberculosis
• Pituitary gland: Gonadotropin insufficiency leading to secondary hypogonadism
• Pancreas: Diabetes mellitus
• Thyroid gland: Hypothyroidism
• Genitalia: Primary hypogonadism
• Joints: Arthropathy in metacarpophalangeal joints, pseudogout

Additional information

• Iron levels have a marked diurnal variation of up to 40% within a day, with higher levels in the morning and lower levels in the evening
• Normal day to day variation is about 25%
• In women, serum iron peak levels are seen during luteal phase with the lowest levels being after menstruation
• Factors interfering with test results include:
• Gross hemolysis
• Anticoagulants such as citrate, EDTA and fluoride-oxalate decreases the serum iron values
• Iron contamination of glassware used in testing
• Failure to follow dietary restrictions prior to sample collection
• Iron-containing medications and vitamin B₁₂ supplements within 24 hours before the test
• A blood transfusion within the past 4 months
• Herbal remedies such as St. John's wort and Saw Palmetto
• Sleep deprivation or extreme stress
• Serum iron and TIBC may be normal in iron deficiency anemia if the hemoglobin is > 9.0 g/dL (or > 90 g/L)
• A single iron measurement is not adequate to diagnose iron deficiency or iron overload
• Related laboratory tests include
• Bone marrow biopsy
• Complete blood count
• Erythropoietin
• Ferritin
• Hemosiderin
• Lead
• Liver biopsy
• Porphyrins
• Siderocyte stain test
• Total iron-binding capacity
• Transferrin saturation

Nl Result

Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.

High Result

Conditions associated with elevated serum iron levels include:

• Idiopathic (primary hereditary) hemochromatosis
• Secondary hemochromatosis
• Anemia and ineffective erythropoiesis
• Hemolytic anemia
• Pernicious anemia
• Sideroblastic anemia
• Thalassemia major
• Liver disease
• After portacaval anastomosis
• Alcoholic cirrhosis
• Porphyria cutanea tarda
• Viral hepatitis
• Chronic iron supplementation
• Excessively high oral intake (rare)
• Multiple blood transfusions
• Parenteral iron dextran
• Iron poisoning
• Acute leukemia
• Hemolysis
• Lead toxicity or poisoning
• Nephritis
• Vitamin B₆ deficiency
• Drugs
• Cefotaxime
• Chemotherapeutic agents
• Chloramphenicol
• Cisplatin
• Estrogens
• Ethanol
• Ferrous sulfate
• Iron dextran
• Iron-protein-succinylate
• Methicillin
• Methimazole
• Methotrexate
• Multivitamin
• Oral contraceptives
• Pyrazinamide
• Rifampin

Low Result

Conditions associated with decreased serum iron levels include:

• Anemia of chronic disease
• Chronic infections
• Lupus
• Rheumatoid arthritis
• Iron deficiency anemia
• Achlorhydria
• Chronic blood loss
• Gastrectomy
• Inadequate absorption
• Increased demand
• Nutritional
• Small bowel disease
• Chronic blood loss
• Gastrointestinal
• Uterine
• Acute illness
• Carcinoma
• Chronic renal failure
• Hypothyroidism
• Increasing age > 70 yrs
• Nephrotic syndrome
• Paroxysmal nocturnal hemoglobinuria (PNH)
• Pernicious anemia remission stage
• Postoperative state
• Pregnancy (third trimester)
• Protein malnutrition (Kwashiorkor)
• Stress
• Drugs
• Acetylsalicylic acid
• Allopurinol
• Antibiotics
• Cholestyramine
• Corticosteroids
• Corticotropin
• Deferoxamine
• Metformin
• Oxymetholone
• Pergolide
• Progesterone
• Pyrazinamide
• Risperidone
• Testosterone

References

• ARUP's Laboratories®. Iron & Iron Binding Capacity. [Homepage on the Internet] ©2007. Last accessed on March 20, 2007. Available at URL: http://www.aruplab.com/guides/ug/tests/0020420.jsp
• Brandhagen DJ et al. Recognition and management of hereditary hemochromatosis. Am Fam Physician. 2002 Mar 1;65(5):853-60. Available at URL: http://www.aafp.org/afp/20020301/853.html
• Centers for Disease Control: Iron Overload and Hemochromatosis. [Homepage on the Internet]. Last reviewed on August 24, 2006. Last accessed onMarch 20, 2007. Available at URL: http://www.cdc.gov/ncbddd/hemochromatosis/index.htm
• eMedicine from WebMD®. Anemia. [Homepage on the Internet] ©1996-2006. Last updated on January 29, 2007. Last accessed on March 20, 2007. Available at URL: http://www.emedicine.com/med/topic132.htm
• Ghaziani T et al. Serum measures of iron status and HFE gene mutations in patients with hepatitis B virus infection. Hepatol Res. 2007 Mar;37(3):172-8.
• Kuloqlu M et al. Serum iron levels in schizophrenic patients with or without akathisia. Eur Neuropsychopharmacol. 2003 Mar;13(2):67-71.
• LabTestsOnline®. Serum Iron. [Homepage on the Internet]© 2001-2007. Last reviewed on March 10, 2006. Last accessed on March 20, 2007. Available at URL: http://www.labtestsonline.org/understanding/analytes/serum_iron/test.html