DIAGNOSTIC SIGNIFICANCE OF RED CELL INDICES IN BETA ...

1 E:/Biomedica/Biomedica/Vol. 21, Jul. Dec. 2005/Bio-6 (A). DIAGNOSTIC SIGNIFICANCE OF RED CELL INDICES . IN BETA-THALASSAEMIA TRAIT. *ZAHID HUSSAIN, **NAUMAAN MALIK, AND **A. S. CHUGHTAI. *Department of Hematology, Services Institute of Medical Sciences / Services Hospital, Lahore **Department of Pathology King Edward Medical College, Lahore znd **Chughtais Lahore Lab, Lahore The purpose of this study was to evaluate the formulae for the diagnosis of beta-thalassemia trait cases in settings where electrophoresis is not available. The study included 50 cases of beta-thalassaemia trait already diagnosed by Hb. electrophoresis. CBC samples were analyzed on Sysmex K4500 and red cell INDICES were used to evaluate formulae for differentiating beta- thalassaemia trait from iron deficiency anaemia. The formula MCV/RBC and MCH/RBC. identified 56% of the cases. Formula MCV - (5 Hb)- RBC - identified 54% of beta- thalassemia trait cases. The formula MCV MCH identified 92% of cases.

2 RBC INDICES given by 100. electronic counters can be used to differentiate iron deficiency anaemia from beta-thalassaemia trait at least provisionally in areas where Hb. electrophoresis is not available. Key words: Beta thalassaemia trait and red cell INDICES . INTRODUCTION than 5-0 107. Measuring coefficient of variation by Beta thalassaemia minor is the most common electronic counters is an excellent technique for form of thalassaemia. It is common in Greeks, rapidly distinguishing -thalassaemia trait from Turks, Cypriots, Italians and to a lesser extent the iron deficiency anaemia. It is more than 14% in Indian subcontinent. However it can occur in iron deficiency and less than 14% in -thalas- subjects of any ethnic saemia Several formulae have been Mostly the patients are diagnosed on routine proposed for differentiating iron deficiency from blood examination and sometimes the disease -thalassaemia trait. Although these formulae may manifests itself during stress such as identify majority of uncomplicated cases they do not work well in children, during pregnancy or The identification of -thalassaemia minor is when there are complicating The formula essential for two reasons.

3 Firstly to differentiate it MCV-(5 Hb)-RBC-K, where K is a constant from iron deficiency since both present as determined by calibrating the electronic counters, microcytosis and hypochromia. Secondly for a positive value indicates iron deficiency and a prevention of beta thalassaemia major by genetic negative value suggests -thalassaemia trait9 In counselling. Through genetic counselling birth rate 1973 Metzner10 gave the formula MCV/RBC. of -thalassaemia major can be reduced by as According to this formula a value less than 13. much as 90%.3. indicates -thalassemia trait. A similar formula Haemoglobin electrophoresis is essential for MCH/RBC was also A value of over definite diagnosis of -thalassaemia trait cases. indicates iron deficiency whereas a value under Normally Hb A2 is less than but in - indicates thalassaemia trait. MCV2 MCH/lOO is thalassaemia trait it is more than In areas another formula in which a value less than 1530. where modern equipments for diagnosis are not indicates thalassaemia Yet another method available, a simple morphologic criterion has been has been This method requires the proposed.

4 It is based on microcytic red cells , target availability of a newer generation of haematology cells and basophilic stippling on peripheral blood analyzers which can give percentage of hypo- films. Red cell INDICES are used for initial screening chromic red cells and prcentage of microcytic red of marriage cases in high risk areas6. The red cell cells . The formula is discriminating beta-thalas- INDICES give more reliable diagnosis. In thalas- saemia trait saemia trait cases MCV and MCH are low while index = RDW MCV % Hvpochromic RBC + MCH. MCHC is normal. Red cell count is often more 100 RBC % microcytic RBC. Biomedica Vol. 21 (Jul. - Dec. 2005). 130 ZAHID HUSSAIN, NAUMAAN MALIK, AND A. S. CHUGHTAI. According to them this formula is able to identify thalassaemia trait cases which was high and very 100% of beta-thalassaemia trait cases. similar results were quoted by another group. This study was designed to evaluate reliability Although the finding of a high HB A2 by Hb.

5 Of some of the above mentioned formulae. The aim electrophoresis is a gold standard for the diagnosis is to find some reliable means to provisionally of -thalassemia trait but it is not available at all diagnose thalassemia trait cases in settings where places. Thus several attempts have been made to electrophoresis is not available. diagnose the condition by using red cell INDICES . In the present study MCV/RBC ratio was able to detect 28 (56%) cases of -thalassaemia trait. The MATERIALS AND METHODS same ratio was studied by others9. Other and It was a retrospective study of 50 cases of - concluded a predictive value of for the thalassaemia trait from public sector hospitals of correct identification of -thalassaemia trait. Lahore area. They were diagnosed on Hb. MCH/RBC ratio was able to predict 28(56%). electrophoresis and for whom INDICES given by subjects having -thalassaemia trait. The discri- haematology analyzer were available. Haemato- minant factor MCV- (5 Hb)-RBC-84 was able logy counter Sysmex K4500 was used for red cell to predict 27 (54%) cases of -thalassaemia trait.

6 INDICES . Data of these cases was scrutinized for the The same formula was applied predicted 417 out of present study. However we are unable to analyze 455 cases of -thalassemia trait9. In another study the formula given by Vicinanza13 because of non- they were able to predict 398 out of 435 ( ). availability of haematology analyzer which can cases of -thalassaemia trait. Shine and Lal give percentage of microcytic and hypochromic red formula MCV^ MCH was applied by England cells . 100. and Fraser, and it failed to distinguish iron RESULTS AND OBSERVATIONS deficiency from heterozygous -thalassae-mia12. In In the present study a total of 50 cases of - the present study it was able to correctly identify thalassaemia trait diagnosed by Hb electrophore- 46(92%) subjects having -thalassaemia trait. In sis were included. Thirty (60%) of the subjects the present study we have selected only diagnosed were females while 20 (40%) were males. cases of -thalassaemia trait.

7 These formulae are In all the cases the value of haemoglobin was to be evaluated in cases having microcytic and low with a mean SD of gm/dl. Red hypochromic picture and there is a need for cell count was 10^12/L. Haematocrit further evaluation by another study. value was L/L. The MCV was also low fl. Similarly MCH was low Table 1: Formulae for distinguishing between p- pg. The MCHC was normal thalassemia trait and iron deficiency g/dl. Findings on Hb electrophoresis were anemia. characteristic. Hb A2 was in a range of to The formulae previously mentioned were Beta applied and the following results were found. Iron Formula thalassemia MCV/RBC and MCH/RBC correctly identified 28 deficiency trait (56%) cases. The formula MCV-(5 Hb) identified 27 (54%) cases of -thalassaemia trait. MCV / RBC <13 > Shine and Lal formula was relevant in maximum MCH / RBC < > number 46(92%) subjects of -thalassaemia trait. All the four formula had a predictive value in MCV - (HBx5) -RBC-K <0 >0.

8 24 (48%) subjects and in 4 (8%) subjects three formulae had this value. In one case (2%) two MCV^xMCH / 100 <1530 >1530. formulae and in 14(28%) cases one formula had a positive predictive value for -thalassaemia trait cases. It was concluded that the facility for Hb electro- phoresis is not available at many places in Pakistan. Red cell INDICES given by electronic DISCUSSION. counters can be reliably used to differentiate iron In the present study Hb, HCT, MCV and MCH. were low and MCHC was normal which is deficiency anaemia and -thalassaemia trait. By comparable to studies conducted by other authors. applying the aforementioned formulae it is Hb A2 is the important finding to diagnose - possible to identify majority of -thalassaemia Biomedica Vol. 21 (Jul. - Dec. 2005). DIAGNOSTIC SIGNIFICANCE OF RED CELL INDICES IN BETA-THALASSEMIA TRAIT 131. Table 2: Average SD as obtained in the study. Hb RBC HCT MCV MCH MCHC HbA HbA2. trait cases. Their accuracy is improved when read Pootrakul P, Fuchareon S.

9 Analysis of in conjunction with peripheral smears. Another hematological data of thalassaemia cases. Acta study need to be carried out involving microcytic Haematol JPN 1989: 52 (4) 792-95. and hypochromic cases. 8. Bessman JD, Feinstein DI. Quantitative anisocytosis as a discriminant between iron deficiency and thalassaemia minor. Blood 1979, 53. REFERENCES (2): 288-93. 1. Barbara J Bain; Blood cells , A practical guide. Ist 9. England JM, Fraser PM. Differentiation of iron Ed. Philadelphia: Lippincot Company 1989: deficiency from thalassaemia trait by routine blood 254-309. count Lancet 1973; 449-52. 2. Pearson HA, O Brien R, MC Intish SM. Screening of 10. Metzner WL. (1973) differentiation of iron thalassaemia trait by electronic measurement of deficiency from thalassaemia trait Lancet 882. MCV, N. Eng J Med 1973; 351-53. Quoted by Barbara J. Bain; Blood cells . A practical 3. Saleem M. Thalassemia in Pakistan. One day guide company East Washington symposium on thalassaemia in Pakistan 1991 Square Philadelphia, PA, 19105 USA.

10 Symposium 1-4. 11. Srivastava PC: Differentiation of thalassaemia 4. Motum PL, Lindeman, Hamilton TJ, Trent RJ minor from iron deficiency Lancet 1973; 154-55. Australian p-thalassaemia; A high hemoglobin A2 Quoted by Barbara J. Bain. Beta thalassemia due to a 12 Kb deletion 12. Shine I, Lal S. A strategy to detect -thalassaemia commencing 5 to the Beta globin gene. Br J. minor: Lancet 1977; 692. Haematol 1992; 82: 107-13. 13. Vicinanza P, Lucio C, Franco F, Vaccoro E, 5. CaoA, Rosatell MC, Leoni GB et al. Antenatal Cancellario S, Vicinanza M, Andretta C, Caputo D, diagnosis of beta thalassaemia in Sardinia. Ann NY Pistolese G, Rotoli B, Lab Hematol; 2002; 193-199. Acad Sci 1990; 215-25. 14. Hashmi JA., Farida Farzana, Nishat Ali, Razia J. 6. SamaVat A, Modell B. Iranian national Rahimatoola, Hematologic findings in 122 cases of thalassaemia screening programme. BMJ 2004: Beta thalassaemia trait studied at Karachi. Pakistan 1134-1137. J. Medical Res.