Iron

DESCRIPTION:
Iron is ingested through food, where it exists in either its divalent (ferrous form) or trivalent (ferric form). Within the intestinal lumen, it is reduced to the divalent form, as only in this state can it pass through cell membranes. In the epithelial cells of the intestine, iron reverts to the ferric form (Fe+++) and then enters the plasma, where it binds to the protein transferrin (siderophilin). Iron bound to transferrin is normally transported to organs, where it is taken up by the protein apoferritin, and then stored as ferritin and hemosiderin. The majority of iron reserves are found in the liver, with smaller amounts in the bone marrow and spleen. The total amount of iron in the body of a healthy adult male is approximately 3.5 g, and 2.45 g in an adult female. 66–70% of this amount is found in hemoglobin, 4% in myoglobin, and approximately 30% in storage (as hemosiderin and ferritin). A small portion is also part of other compounds in the body (flavoproteins, catalase).

DETERMINATION:
Iron is determined by a direct photometric method. The sample for analysis is serum or heparinized plasma. Sample stability is 7 days at 20°C to 25°C, 3 weeks at 2°C to 8°C, and 1 year at -20°C. The sample for analysis must not be hemolyzed.

CLINICAL SIGNIFICANCE:
1) Physiological variations in iron concentration: Normal pregnancy – Progressive decrease in iron concentration after the expected delivery date with a simultaneous increase in TIBC. 2) Pathological changes in iron concentration: A) Increased iron concentration in cases of: Acute and portal cirrhosis / Acute and subacute liver necrosis / Acute intermittent porphyria / Acute lymphatic leukemia / Acute iron poisoning / Alcoholic cirrhosis / Anemia due to vitamin B6 deficiency / Aplastic anemia / Liver disease (acute hepatitis) / Cis-Platin therapy / Folic acid deficiency / Gaucher’s disease / Hemolytic anemia / Hepatogenic hypersideremia / Homozygous thalassemia / Hormonal therapy / Idiopathic hemochromatosis / Infections / Intake of iron-containing medications / Massive and frequent transfusions / Megaloblastic anemia / Liver cell necrosis / Oral contraceptive use / Pernicious anemia / Polyarteritis nodosa / Repeated blood transfusions / Porphyria cutanea tarda / Excessive iron intake (intravenous or intramuscular) / Secondary hemochromatosis / Sideroblastic anemia / Thalassemia minor and major / Lead poisoning / Estrogen use. B) Decreased iron concentration in cases of: Iron deficiency anemia / Celiac disease / Blood donors / Absorption defects / Infants and young children (low iron reserves in newborns) / Breastfeeding / Exudative enteropathy / Gastrointestinal bleeding / Hemodialysis / Hypo- and atransferrinemia / Hypothyroidism / Histoplasmosis / Myocardial infarction / Infections / Monotonous diet (alcoholics, pure cow’s milk in newborns, vegetarians) / Chronic inflammation / Bleeding due to salicylates or butazolidin / Kwashiorkor / Malaria / Malignant diseases / Massive hemoglobinuria due to intravascular hemolysis / Menorrhagia and metrorrhagia / Insufficient iron intake / Nephrotic syndrome / Neoplasia / Gastric or intestinal resection / Septicemia / Stress / Typhoid fever / Pregnancy / Uremia.

RISK FACTORS:
Decreased values:
Biological variation over 24 hours and day-to-day. Diurnal rhythm: evening. EDTA. Fluorides. Iron loss during deproteinization. Lipemia. Menstrual cycle. Oxalates. Stress. Pregnancy. Healthy individuals show variations up to 12.9% during the day and 26.6% day-to-day.
Increased values:
Alcoholism. Diurnal rhythm: morning. Hemoglobin – a concentration of 140 mmol/L increases iron concentration by 2–4 mmol/L. Hemolysis. Iron concentration depends on food intake and can change within 10 minutes. Lithium heparin. Inappropriate tubes. Sample contamination. Oral contraceptives. Tourniquet application > 1 min (6.7%). Serum obtained by routine collection methods contains 10–30 mg/L of free hemoglobin. 1 mg of hemoglobin binds 3.5 mg of Fe, which can lead to an increase in serum Fe of 0.6–2.2 mmol/L. Gender.

EFFECT OF MEDICATIONS:
Decreased values:
deferoxamine, penicillamine, pyrazinamide
Increased values:
cefotaxime, rifampin, iron dextran complex

RESULT:
The reference interval depends on gender, age, and the determination method. The reference interval is displayed on each validated report.