Which anemia has red cell morphology similar to that seen in iron deficiency anemia?

1. Explain "tasting for eating ice". Spooning of nails.

• Pica: Desire for unusual items like Clay, Starch. Ice in this case. A peculiar symptom of iron deficiency anemia.

• Koilonychias: Spooning of nails seen in iron deficiency anemia.

2. How reliable is physical examination in diagnosing anemia?

• Early clinical recognition of anemia by assessing pallor of conjunctiva is poor.

Obviously patient is anemic. Her red cell mass is decreased. In order to understand and manage this patient we need to have some basic knowledge about Red cells..

3. What is the normal

• Maturation stages

• Morphological characteristics

• Hemoglobin synthesis

• Red cell turnover

• Control of erythropoiesis

Maturation stages

Morphological characteristics

• Normal RBC's

  • Anucleate biconcave discs

  • Disc with central pallor

  • Size

• Reticulocytes

  • Reticulocyte usually the first stage RBC"s released from marrow into peripheral blood

  • Cytoplasm may be slightly bluish-pink due to residual RNA (polychromasia)

Hemoglobin synthesis involves 2 biosynthetic pathways

• Heme

  •  Heme consists of 4 pyrrole groups joined into large ring with ferrous iron incorporated into center.

• Globin chains

  • Globin chains contain approximately 150 amino acids

  • Two globin dimers form hemoglobin 

  • Most important hemoglobin is hemoglobin A comprising 95% of the hemoglobin normal red cell.

  • Errors in globin synthesis result in hempglobinopathies or Thalassemias.

Red cell turnover

• A normal life-span of RBC's is about 120 days

• Aging RBC's are removed by mononuclear phagocytic engulfment in spleen

• Heme and globin chains are separated

• Heme is divided into iron (which is recycled) and porphyrin rings (eliminated as bilirubin)

• Globin is dismantled into amino acids

Control of erythropoiesis

• less than 1% of RBC's are replaced every day.

• Normal levels of Hg levels are maintained through a feedback mechanism involving erythropoetin

• A sensing mechanism responds to the tissue oxygen content within the kidney and results in the release of erythropoietin.

4. What is the main function of RBC's?

• Carry oxygen to the tissue

• Return to lungs carrying carbon dioxide

Transport of oxygen is influenced by pH, 2-3-DPG level and valence of iron.

Let us go through the steps in evaluation of a patient with anemia.

1. Distinction between hypo and hyperproliferative anemia

2. Use of red cell size to further narrow down the possibilities

3. Review the blood smear

5. First step is to make a distinction between hypo- and hyperproliferative anemia. How will you decide that? What is your understanding of  those terms?

Reticulocyte count helps to categorize the anemia into hypo-or hyper-proliferative type.

• Normal 0.5-1.5%

Hypoprolifearative: 

• Decreased reticulocytes

• Bone marrow unable to produce requisite number of RBC's 

• Lack of essential substance (iron, B12, folate) or invasion of marrow by a disease process as in leukemia , Aplastic anemia

Hyperproliferative: 

• Increased reticulocytes

• Cause of anemia outside marrow

  • Hemolytic anemia

  • Hemorrhage

  • Post anemia treatment

• Decreased survival of rbc's

• Marrow normal and responds adequately by increasing the output

6. How will you recognize reticulocytes in the peripheral smear?

• Reticulocytes are defined as immature red cells seen in the peripheral blood that contain at least two dots of reticulin material reactive with new methylene blue (NMB) in their cytoplasm. 

• More immature forms have multiple dots and small networks of skeins of bluish material. These remnants are residual ribosomal RNA used for hemoglobin synthesis in the developing erythrocyte. 

• The RNA is too finely distributed to form networks on Wright's stain; a supravital stain causes precipitation and aggregation of the RNA and creates the dots and skeins of reticulin. 

• RNA-containing red cells are usually grayish on Wright's stain and contrast well with mature, orthochromic or pink red cells, providing a clue to the presence of a reticulocyte response. 

7. How do you count and express reticulocyte count? 

There are three ways to express retic response

1. Retic count

2. Corrected retic count

3. Absolute retic count

Retic count: Reticulocytes are counted as the number of NMB-reactive cells per 1,000 red cells and expressed as percent reticulocytes (absolute number per 100 red cells).

•  Inter-observer variation and uneven distribution of reticulocytes on the new methylene blue smear introduces a high analytic variation in reticulocyte counting; interlaboratory coefficients of variation in the 20% range are common, a degree of imprecision of which every clinician should be aware. Duplicate reticulocyte counts or 3-day average values may help to reduce the imprecision of the raw reticulocyte count.

Her  reticulocyte count  is 2.5%. 

Corrected reticulocyte count  = %reticulocyte X (Patient's Hct/Expected normal Hct of 40)

Our patient's Corrected reticulocyte count is 2.5 x 23 / 40. It is 1.2%. 

Less than 2% =  hypoproliferative type. This means that her anemia is due to underproduction of red cells by the bone marrow. 

Absolute Reticulocyte count

• The absolute reticulocyte count can also distinguish between hypo/hyperproliferative anemia.

• If the absolute reticulocyte count is 100,000 mm3 or higher, the anemia is hyperproliferative type (i.e. hemolytic anemia or anemia of acute blood loss). 

• If it is less than 100,000 mm3 the anemia is hypoproliferative (iron, B12, or folic deficiency, anemia of chronic disorder etc.).

The absolute reticulocyte count in our patient is 69,000/mm3. 

Now we know that we are dealing with hypoproliferative anemia. The next step is to evaluate the size of RBC's

8. How do MCV and RDW help you in the diagnostic work-up of anemia? Do the other indices-Mean Corpuscular Hemoglobin (MCH) and Mean Corpuscular Hemoglobin Concentration (MCHC)-add anything?

• Normal MCV is 85-95fl

  • MCV divides the anemia in micro, normo, and macrocytic types. 

  • Each of these categories suggest a particular differential diagnosis. 

• RDW (red cell distribution width) measures anisocytosis. 

  • RDW is abnormal in a majority (more than 90%) of cases of iron deficiency. It is however normal in thalassemias and anemia of chronic disorder. 

  • Thus a patient who has low MCV and high RDW is very likely to have iron deficiency anemia. 

  • On the other hand if the RDW is normal the low MCV may suggest a thalassemic syndrome or an anemia or chronic disorder. 

• MCH and MCHC do not provide additional information.

In our patient the MCV is 74 fl  indicating that we are dealing with microcytic anemia. 

The next step is to review the peripheral smear. 

She has microcytic hypo chromic anemia.

9. What is the differential for microcytic hypo chromic anemia.

• Iron deficiency anemia

• Thalassemia

• Sideroblastic anemia 

• Chronic disease (Rheumatoid arthritis, Renal failure etc)

10. Does microcytic anemia represents a maturation defect or abnormal hemoglobin synthesis?

• Microcytic : Abnormal hemoglobin synthesis 

• Macrocytic: A maturation defect (B12, Folate deficiency)

11. Iron deficiency leads to faulty heme synthesis. What are the consequences?

• There is disturbance of proliferation and maturation of erythroblasts due to deficient heme synthesis

• Hemoglobin decreases and the red cells become small (microcytic with reduced hemoglobin concentration (hypo chromic)

12. How would you proceed to differentiate between the different possibilities for  microcytic anemia?

• Iron deficiency

  • Retic count decreased

  • RDW is high

• Thalassemia

  • Retic count elevated

  • RDW is normal

• Chronic disease

  • Retic count decreased

  • RDW is normal

13. What further tests would you like to do  to confirm iron deficiency in this patient? 

1. Serum Iron

2. Total Iron-binding capacity

3. Saturation

4. Ferritin

Serum Iron measures Transferrin-associated ferric ion  Normal Range: 12.7 to 35.9 �mol/L (60 to 180 �g/dl) Decreased serum iron levels may precede changes in red cell morphology or in red cell indices All transport iron in the plasma is bound in the ferric form to the specific iron-binding protein, transferrin. Serum iron refers to this transferrin-bound iron. Serum iron concentration is increased in the sideroblastic anemia's and in some cases of thalassemia.

Total Iron-binding capacity  Normal Range: 45.2 to 77.7 �mol/L (250 to 410 �g/dl) TIBC, the concentration iron necessary to saturate the iron-binding sites of transferrin, is a measure of transferrin concentration.

• Transferrin carries 2 iron atoms per molecule 

• Transferrin is normally 30% bound to iron 

• TIBC reflects a measurement of serum Transferrin 

• Measured by saturating all available binding sites 

Transferrin Normal range170-370 mg/dl 

Saturation of transferrin is calculated by the following formula % Transferrin Saturation = Serum Iron (mol/L) X 100.: Normal mean transferrin saturation is approximately 30%. Normal range 20% to 50%

• Iron deficiency anemia

  • Serum Iron Low

  • TIBC Increased

  • Saturation of Transferrin  Reduced often <16%

• Chronic disease

  • Serum Iron normal

  • TIBC Decreased or normal

  • Saturation of Transferrin  Reduced >16%

A normal plasma iron level and iron-binding capacity do not rule out the diagnosis of iron deficiency when the hemoglobin level of the blood is above 90 g/L (9 g/dl) (females) and 110 g/L (11g/dl) (males). 

Her serum iron is 21 microgram/dl and total iron binding capacity 408 microgram/dl.  Her iron saturation is about 5%. 

14. What is ferritin? How do you interpret low and high ferritin values?

• Ferritin is protein that carries iron. 

• Its exact function is not known. 

• Ferritin values however reflect the total iron stores of the body very well.

• Low ferritin values are diagnostic of iron deficiency.

• Most sensitive for iron deficiency anemia

• Since ferritin is an acute phase reactant high values do not necessarily rule out iron deficiency. 

• Very high values (about 1,000) may indicate presence of hemochromatosis.

• Normal : 32-100 ng/ml

Her Serum Ferritin is 3 

15. Is there a need to obtain a hemoglobin electrophoresis?

Hemoglobin electrophoresis should not be ordered at this time. She could have an alpha thalessemia trait but hemoglobin electrophoresis is not of any help in diagnosing that condition. In iron deficiency, levels of Hg A2 and F may also be low, making diagnosis of �-thalassemias more difficult.

16. Should one do a bone marrow test in this patient? If one did , what would you expect to see?

The bone marrow should not be done. There is already strong evidence for iron deficiency anemia. If it is done , stains for iron will show depletion of Iron stores. There will be erythroid hyperplasia.

17. Could she have 'anemia of chronic disorder'? What are the known mechanisms of anemia of chronic disorder?

• She should not have anemia of chronic disorder. 

• There are no apparent chronic disorders. (Chronic infection, Rheumatoid arthritis, Chronic renal failure, Malignancy)

• Iron studies in ferritin values, along with RDW suggest iron deficiency anemia.

• In anemia of chronic disorder, Fe utilization is poor, red cell survival is shorter. 

• This anemia is mediated through various cytokines, especially TNF, IL-1.

18. Your intern wants you to order a B12 and folate level also, for sake of completeness. Is that justifiable?

This patient has iron deficiency anemia due to multiple pregnancies in a short period of time. It is not justifiable to order a B12 and folic acid level in this patient.

Now that we have confirmed that this patient has iron deficiency anemia, let us understand few basics.

19. What tissues /cells require Iron for normal development?

• RBC's: Anemia

• Iron containing enzymes

  • Depletion results in changes in Nails and mucous membranes.

    • Ridges and spoon shaped nails

    • Mal-absorption

    • Esophageal web

20. What are the normal resource for iron in diet?

• Liver and red meats

• Apricots, peaches, prunes apples, grapes

• Eggs

• Spinach

Vitamins and many food items (Cereal) are fortified with iron.

21. What is the daily requirement of iron for a normal adult? Is it different for females or pregnant women?

• The daily requirement in a adult male is 1mg. 

• In woman it is 1.5 to 2mg. per day because of menstrual loss. 

• Pregnancy requires an additional intake of .9 to 1 gm of iron. Therefore, during pregnancy iron supplements are necessary.

22. This patient's old records indicate that she did not have a murmur in the past. Should one obtain an echocardiogram to rule out valvular heart disease?

She very likely has a flow murmur due to her anemia. If her murmur persist after iron therapy, further studies can be undertaken.

23. What are the common causes of iron deficiency anemia? Children, Young adult, Older adult. Males, Females.

Most important cause is chronic blood loss.

Menstruating women:

• Excessive menstrual flow. 2 mgm of iron per day.

• Multiple pregnancies close to each other. About 500-1000 mg of iron lost per pregnancy.

Males and Post menopausal women

GI tract blood loss

• Cancer colon

• Ankylostoma duodenale (Underdeveloped countries)

• Hemorrhoids

Nutritional deficiency (Not in USA)

Malabsorption (Sprue, gatrectomy)

Rare causes

• Hemoglobinuria

• Hereditary hemorrhagic telengiectasia (Nose bleeds, GI bleeds)

24. What are the clinical sequelae to iron deficiency anemia?

• Asymptomatic until late

• Pica

• Angulostomatitis

• Koilonychias

• Fatigue

• Dysphagia

• Angina

• High output state

• Congestive heart failure

25. What is your therapeutic strategy for treatment of iron deficiency anemia?

• Identify the source of blood loss and plan to take care of it

• Provide iron supplement

26. What treatment would you prescribe for this patient?  How soon should you expect a response?

• Ferrous sulfate 325 mg po tid

• Reticulocyte response in 2 weeks (<10%)

• About 8 weeks to near normal hemoglobin

27. How long will you treat her with iron supplement and why?

• This patient should be put on iron supplements, along with vitamin supplement for the duration of her pregnancy plus 6 to 8 months afterwards.

• Prolonged duration of therapy even after normalization of hemoglobin is to restore iron stores in bone marrow.

28. In which part of GI tract is iron absorbed? What else is necessary for iron absorption?

• Iron is absorbed in duodenum and proximal jejunum.

•  Hydrochloric acid produced by the stomach is helpful in iron absorption, as it reduces ferric to ferrous form.

29. Are there any problems associated with iron therapy?

• GI distress. Start with low dose and gradually increase

• Black stools: Without an advanced warning patient might think it is malena.

• Antacid use to be discontinued: Impairs absorption

30. Is there a role for Blood transfusion?

You do not need blood transfusions even in severe chronically anemic patients. Patients adapt to chronic anemia extremely well and Iron replacement therapy can correct the problem gradually. You can do harm from transfusion  by throwing them into heart failure, for already they have a high output state. 

Is microcytic anemia the same as iron deficiency anemia?

What is the morphology of RBC in iron deficiency anemia?

Is iron deficiency anemia normocytic or microcytic?

How do you differentiate b thalassemia and iron deficiency anemia?