Ginette A. Hinds

1. Ginette A. Hinds • Seminar Presentation 1 • “A method to estimate prevalence of iron deficiency and iron deficiency anemia in adolescent Jamaican girls.” • 02/23/00

2. RATIONALE • To determine the effectiveness of a 3-variable model, employing measurements of mean corpuscular volume (MCV), serum ferritin levels, and erythrocyte protoporphyrin levels, to define iron deficiency anemia in young Black girls.

3. ANEMIA Anemia is defined as a decrease in the ability of the blood to carry oxygen due to: • A decrease in the total number of erythrocytes, or • a diminished concentration of hemoglobin per erythrocyte

4. Erythrocytes The major functions of erythrocytes are: • · To carry oxygen taken in by the lungs to the tissues • · To carry carbon dioxide produced by the cells during cellular respiration to the lungs to be expired.

5. Hemoglobin • Hemoglobin (MW 64500) contains 4 iron-containing heme groups that are linked to 4 globular protein chains (2 alpha and 2 beta). • The heme group is a metal complex composed of a protoporphyrin IX ring with a ferrous iron (Fe2+) at its center. • The protoporphyrin IX ring consists of 4 pyrrole rings united by methene bridges. When iron is combined with the protoporphyrin IX ring, it is called heme. The oxygen transported by the hemoglobin binds to the iron at the center of the heme molecule.

6. The Study • The sample included 419 13-14 yr.-old girls of African Descent who lived at sea level. • Their blood was obtained by venipuncture.

7. 3 variables,besides hemoglobin concentration and hematocrit were measured: • · Serum Ferritin levels – measured by ELISA • · Erythrocyte Protoporphyrin Levels – determined by an extraction method • · Mean Corpuscular Volume (MCV) – machine counter

8. Hematocrit • ·The % volume of whole blood that is occupied by RBC’s • ·  Avg. for men is 45-49%; Avg. for women is 36-45% • Cutoff for anemia: < 36%

9. Hemoglobin Concentration • · A measure of the volume of hemoglobin in a whole blood sample • ·  Normally 1/3 of hematocrit • ·  Avg. for men is 140-180 g/L; Avg. for women is 120-160 g/L

10. Erythrocyte Protoporphyrin • ·A measure of the amount of protoporphyrin molecules that combined with iron to produce the heme group of hemoglobin. • ·  Erythrocyte protoporphyrin values • > 700g/L RBC’s is an indicator of iron deficiency

11. Serum Ferritin Levels • ·Ferritin is a protein that has a considerable store of iron (about 25% of body’s iron) • · Serum ferritin levels therefore measure how much iron is stored in the body. • · Iron deficiency is indicated if serum ferritin < 10g/L

12. Mean Corpuscular Volume (MCV) • Used to describe the average size and volume of red blood cells • Iron deficiency is indicated if MCV < 78fL

13. Iron deficiency was considered present if an individual had two or more abnormal values from among the last three indicators.

14. ResultsFig. 1 • Mean hemoglobin concentration decreases with increasing numbers of abnormal values. • The girls who were considered iron-deficient (>2 abnormal variables) had a mean Hb concentration of 106.4 +/- 13.6 g/L, and those who were non-iron deficient had a mean Hb conc of 126.1 +/- 9.2 g/L

15. ResultsTable 2 • ·  The % of girls having 2 or more abnormal variables (and therefore classified as iron deficient) was 7.6%, • The % of girls considered to have iron deficiency anemia (iron deficient AND Hb conc < 107g/L) was 4.3%

16. Conclusion • A hemoglobin cutoff value specific for iron-deficiency anemia: 107 g/L was obtained • The cutoff value to determine iron-deficiency anemia in the US is <118 g/L. • The Jamaican girls still had a higher prevalence (1.6 to 21 times) of iron-deficiency anemia with the lower 107 g/L value used in this study than their American peers.

17. Conclusion (con’t) • A hemoglobin cutoff for anemia for Blacks that effectively differentiates between iron-deficient and non-iron deficient individuals is lower than conventional cutoffs.