Iron Deficiency | Iron Studies - MedSchool
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Iron Studies
 

Iron Deficiency

 
 

Overview

    • Markers of Iron Deficiency

    • Reduced serum iron
    • Reduced ferritin
    • Increased serum transferrin
    • Reduced transferrin saturation
    • Microcytic, hypochromic anaemia
  • The most specific marker of iron deficiency is serum ferritin, and as such a reduced serum ferritin makes iron deficiency likely. Ferritin can be elevated in the setting of an acute phase response and can appear normal, though a serum concentration above 100μg/L makes iron deficiency unlikely.
  • Iron deficiency will present with an elevated serum transferrin and elevated total iron binding capacity; these two measures are proportional to each other and relatively interchangeable. The transferrin saturation (TSat) is the percentage of iron that is bound to transferrin and is reduced in iron deficiency, though inflammation, infection and malignancy can also reduce the TSat.
  • Serum iron (Fe3+) concentration tends to fluctuate with iron intake, acute and chronic disease and in itself is a poor marker of iron status.
  • The anaemia of iron deficiency tends to be microcytic and hypochromic and the blood film may exhibit poikilocytic changes such as target cells or elliptocytes. Often in early iron deficiency the anaemia is normocytic, with anisocytosis (i.e. an elevated RDW) due to a mix of normocytic and microcytic cells.
  • If iron deficiency is suspected but not confirmed, improvement in haemoglobin following a trial of iron supplementation can clinch the diagnosis.

Aetiology

    • Causes of Iron Deficiency

    • Nutritional deficiency
    • Malabsorption - e.g. coeliac disease, gastric surgery, PPIs
    • Blood loss - particularly menstrual and gastrointestinal loss; regular blood donation
    • Pregnancy
  • Blood loss is the most concerning cause of iron deficiency, most commonly due to menstrual or gastrointestinal loss. Poor iron intake is a common cause of deficiency, and less commonly deficiency can be caused by malabsorption. Iron deficiency may occur in late pregnancy, though the most common obstetric cause of anaemia is haemodilution.

Clinical Features

    • Clinical Features of Iron Deficiency

    • History

    • Symptoms of anaemia - fatigue, lethargy, lightheadedness, shortness of breath, chest pain, headache
    • Pica - craving of non-foods such as ice, chalk and dirt
    • Restless legs syndrome
    • Bleeding - trauma, haematemesis, malaena, haematochezia, menorrhagia
    • Plummer-Vinson syndrome: iron deficiency anaemia, dysphagia and oesophageal webs
    • Family history - bowel cancer
    • Examination

    • Signs of anaemia - conjunctival pallor, pale hand creases, tachycardia
    • Koilonychia: spoon-shaped nails
    • Brittle nails
    • Alopecia
    • Atrophic glossitis
    • Angular stomatitis
Last updated on January 13th, 2020
 
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 Andres E, Serraj K, Zhu J, Vermorken AJ. The pathophysiology of elevated vitamin B12 in clinical practice. QJM: An International Journal of Medicine. 2013 Jun 1;106(6):505-15. Baik HW, Russell RM. Vitamin B12 deficiency in the elderly. Annu Rev Nutr. 1999;19:357-377. Benz Jr EJ. Iron Loading Anaemia. eLS. Brugnara C. Iron Deficiency and Erythropoiesis: New Diagnostic Approaches. Clinical Chemistry. 2003; 49(10): 1573-1578. Cook JD, Flowers CH, Skikne BS. The quantitative assessment of body iron. Blood. 2003; 101: 3359-3363. Goot K, Hazeldine S, Bentley P, Olynyk J, Crawford D. Elevated serum ferritin: What should GPs know?. Australian family physician. 2012;41(12):945-9. Kelly AU, McSorley ST, Patel P, Talwar D. Interpreting iron studies. BMJ: British Medical Journal. 2017 Jun 15;357. Lieu PT, Heiskala M, Peterson PA, Yang Y. The roles of iron in health and disease. Molecular aspects of medicine. 2001 Feb 1;22(1-2):1-87. Lopez A, Cacoub P, Macdougall IC, Peyrin-Biroulet L. Iron deficiency anaemia. The Lancet. 2016 Feb 27;387(10021):907-16.
Metz J. Appropriate use of tests for folate and vitamin B12 deficiency. Australian Prescriber. 1999 Feb 1;22(1):16-8.
Muñoz M, Villar I, García-Erce JA. An update on iron physiology. World journal of gastroenterology: WJG. 2009 Oct 7;15(37):4617.
 Neumann WL, Coss E, Rugge M, Genta RM. Autoimmune atrophic gastritis--pathogenesis, pathology and management. Nat Rev Gastroenterol Hepatol. 2013;10(9):529-541. Rossi E. Hepcidin-the iron regulatory hormone. Clinical Biochemist Reviews. 2005 Aug;26(3):47. Snow CF. Laboratory diagnosis of vitamin B12 and folate deficiency: a guide for the primary care physician. Archives of internal medicine. 1999 Jun 28;159(12):1289-98. Stabler SP. Vitamin B12 deficiency. New England Journal of Medicine. 2013 Jan 10;368(2):149-60. Stanger O. Physiology of folic acid in health and disease. Current drug metabolism. 2002 Apr 1;3(2):211-23. Van Vranken M. Evaluation of microcytosis. American family physician. 2010 Nov 1;82(9). VanWagner LB, Green RM. Elevated serum ferritin. Jama. 2014 Aug 20;312(7):743-4. Waldvogel-Abramowski S, Waeber G, Gassner C, Buser A, Frey BM, Favrat B, Tissot JD. Physiology of iron metabolism. Transfusion Medicine and Hemotherapy. 2014;41(3):213-21.
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