Megaloblastic anemia—etiology and management

indian J Pediatr 1987; 54 : 343-353

Megaloblastic anemia-etiology and management

A.K. Saraya and M.K. Gupta

Hematology Unit, Department qf Pathology, All India Institute of Medical Sciences, New Delhi

The term megaloblastic anemia refers to a characteristic morphology and fun- ctional abnormalities of erythrocytes, leu- cocytes, platelets and their precursors in the blood and bone marrow due to dis- turbed synthesis of deoxyribonucleic acid (DNA) resulting in anemia.

The term megaloblast coined by Ehrlich in 1980 l to describe the abnormal erythroid wecursors of pernicious anemia (PA) is now used in general to denote abnormal erythroid precursors of megalo- blastio anemia.

Pathogenesis of megaloblastic transforma- tion

Megaloblastic anemia results from the slowed DNA synthesis per unit time. 2-4 Megaloblast contains an increased level of ribonucleic acid (RNA) and a slightly increased DNA per cell.2Haemoglobiniza - tion accelerates the maturity of ~ ytoplasm earlier than that of the nucleus leading to nuclear-cytot.lasmic dissociation or asynchronism.

The deoxyuridine (dU) suppression testS, 4 suggests that megaloblastosis is

Reprint requests : Dr. A.K. Saraya, Professor & Head, Hematology Unit, Department of Patho- logy, All India Institute of Medical Sciences, New Delhi-110029.

associated with impaired conversion of deoxyuridine monophosphate (dUMP)5 to deoxythymidine monophosphate (dTMP) resulting in impaired synthesis of one or more nucleotides due to inhibition of thymidylate synthetase enzyme, leading to diminished synthesis of DNA, accumulation of dUMP and deoxyuridine triphosphate, uracil misincorporation, deletion excision of misinicorporated uracil, failure of repair of DNA due to lack of deoxythymidine triphosphate (dTTP) and leakage of DNA fragments. 6 Capacity to exclude uracil from DNA varies in different cells, which determines the sus- ceptibility of various cell lines to megaloblastic changes3 Megaloblastosis is associated with two pathophysiologic abnormalities of erythroid cells; ineffective ery- thropoiesis and decreased life span of circulating red blood cells. There is also ineffective leucopoiesis and thrombo- poiesis.

Etiology

Well known causes of megaloblastie anemia are deficiency of vitamin Bl2 (B12) aud/or foIic acid (FA). Megalo- blastic anemia resulting from other causes axe unresponsive to therapy with B~2 and FA. Figure 1 presents the flowchart of B12 and folate metabolism which

343

344 THE INDIAN JOURNAL OF PEDIATRICS Vol. 54, No. 3

B;i o, ~ t ~ r t . ~ r , ~ . ~ t B~7 ~t~ tv~a tC*~vt ~i i~uIA SE i \ ~ ,0Ar ,o~

c o ~

~ r ~ t t S-~DE t r p~s r f~as f

SYNI' f~S[

ar,ra S ~'C~,~YL Ik;,e ~ r~ to M f l ~ tEw [ l ~ f

J

Br, a (CO + + + ) Trivalent cobalt state of vitamin Bz2 Bl2r ( C O + + ) Bivalent cobalt state of vitamin

.B19 Bx2 s (CO+) Univalent cobalt state of vitamin Bz,,

.~THF Tetrahydrofolate. DHF Dihydrofolate.

provide the understanding of the role of deficiencies of these vitamins in causation of megaloblastosis.

Classification of megaloblastic anemia falls into any of the following etiologic categories : inadequate ingestion, absorption and utilisation; or increased require- merit, excretion or destruction (Table I). 7

Vitamin Bt2 deficiency

B12 is derived from bacterial source only. The chief dietary source for humans is animal protein. Vitamin Bt2 is required for the entry of folate inside the cells and provision of correct folate coenzyme for thymidylate synthetase coenzyme, but the exact mechanism how it is achieved is still uncertain)

Lack oj'Bl2 results in the following defects in folate metabolism 5

(i) Reduced formation of tetrahydrofolate (THF) from methyl tetrahydrofolate (CH 3 THF); (ii) diminished cell concentration of S-adenosyl methionine (SAM) leading to greater accumulation of CH 3 THF due to lack of inhibition of conversion of methylene tetrahydrofolate to CH 3 THF; and (iji) lack of formation of formyl THF, which is also a substrate for folate polyglutamate derivatives, storage forms of folate. Decreased concentrations of SAM is perhaps also responsible for neurological lesions of BI2 deficiency.2,5, 8

In the human cells there are only two cobalmin dependent reactions; adenosyl cobalmin dependent methylmalonyl Co-A mutase; and methyl cobalmin dependent methyl tetrahydrofolatc homo- cystine methyl transferase.2:, 9 Average daily requirement of Bt2 varies from I-2/~g in infants to about 1-5/~g in adults. Daily losses average to 1.3 pg. Total body stores range from 2-5 rag, I~ enough to meet body requirements for 3-5 years 2 of which about 1000 ~g are stored in the liver. Normal plasma levels range from 200-900 pg/ml. 2 A deficiency state is usually present with levels below 200 pg/ml. How- ever, low levels of B12 are not always associated with anemia) 1 In anemic patients with megaloblastosis 84 to 90% showed serum Bl2 below 80 pg/ml.12,13 In 50 non-anemic healthy subjects studied by authors, low serum Blz (<140 pg/ml) were found in 15 (30~o). 14 Ingested food Bi2 after having been freed from its bonds by gastric and intestinal enzymes 15 binds to salivary and gastric B12 binders called 'R' binders to form R-BIz complexes which when exposed to pancreatic pro- teases at intestinal pH of > 7 release its

SARAYA AN O GUPTA : MEGALOBLASTIC ANEMIA 345

Table I. Etiologic classification of megaloblastic anemia

Category

Vitamin B12 deficiency

Decreased ingestion

Impaired absorption

Increased requirements

Impaired utilization :

Folic acid deficiency Decreased ingestion Impaired absorption

II~creased rcquiremel3 t

Impaired utilization Increased Loss

Unresponsive af Vitamin B 12 and Folate

Etiologic mechanism

Poor diet, lack of animal products, strict vegetarianism.

1. Intrinsic factor deficiency. Pernicious anemia. Gastrectomy (total and partial) Destruction of gastric mucosa by caustics. Anti Intrinsic factor antibody in gastric juice. Abnormal Intrinsic Factor Molecule.

2. Intrinsic Intestinal diseases. Familial. Selective malabsorption (Imerslund syndrome). Ileal resection; ileitis, sprue, celiac disease. Infiltrative intestinal disease (e.g. lymphoma, scleroderma).

3. Competitive parasitic infestation. Fish tapeworm, bacteria in diverticula of bowel, blind loops.

4. Chronic pancreatic disease. Pregnancy. Neoplastic diseases, Hyperthyroidism.

Enzyme deficiencies. Abnormal serum vitamin Bxz binding proteins. Lack of transcobalmin II. Nitrous oxide administration.

Poor diet, lack of vegetables, alcoholism, infancy. Intestinal short circuits. Steatorrhoea. Sprue, celiac

disease. Intrinsic intestinal diseases. Anticonvulsants, oral contraceptives and other drugs.

Pregnancy, infancy, hyperthyroidism, hyperactive hae- mopoiesis, exfoliative skin dermatitis, neoplasetic diseases.

Folio acid antagonist, enzyme deficiencies. Haemodialysis. 1. Metabolic inhibitors of purine synthesis: 6 mercapto

purine, 6 tbioguanine; azothioprine. Pyrimidine synthesis : 6 azauridine, thymidylate synthesis : 5 Fluorouracil; deoxyribonueleotide synthesis : Hydroxyurea, Cytosar, arabinoeide, Severe iron deficiency.

2. Inborn Errors : Lesch Nyhan syndrome. Hereditary orotie aciduria Deficiency of Formininotransferase, methyltrans. ferase.

3. Unexplained disorders : Pyridoxine responsive megaloblastic anemia, thia, mine responsive megaloblastie anaemia, erythremic myelosis.

34~ THE INDIAN JOURNAL OF PEDIATRICS Vol. 54, No. 3

BI2 to be attached to intrinsic factor (IF) and form B I 2 - - I F complexes.16,17 The BI2 - - IF complexes pass into the ileum and get attached to the specific receptors in the presence of ionic calcium and p H > 7.18 The absorbed B12 is transported in the blood attached to the various B12 binding proteins. Transcobalmin II (TCII) delivers it to the liver, haemopoietic system and other proliferating cells. A portion of absorbed Bx2 is attached to coabalophilins; transcobalamins I (TCI) and III (TC III) deliver Ba2 only to the liver and perhaps are involved in clearing of undesirable B12 analogues from the body via the bile.19, 20 Normally plasma BI2 binding capacity is about one-third saturated. Of the unsaturated B12 binding capacity about 90~ is due to TC II. 19 Approximately 3 /zg of vitamin Bt2 is secreted into bile daily and reabsorbed from the ilieum. 2 Cobalmin analogues are selectively delivered to human bile, which appears to enhance only the uptake of free B12 and IF-B12 complexes by the receptor of small intestine. Thus enterohepatic cycle is important because it may be a filter of the body to get rid of noxious cobalmin analogues and at the same time selectively enhancing reabsorption of the useful metabolic forms of B12. Interference with this enterohepatic reabsorption of useful Bt2 molecules by intestinal diseases can lead to continued loss of B12.2

Inadequate dietary intake

Deficiency due to inadequate dietary intake is mostly seen in strict vegans.l?,9, 21 Occasionally B12 deficiency is associated with severe general malnutrition. Low serum cobalmin levels are seen in vegetarians and lactovegetarians. Daily cobal-

min availability of a vegetarian diet varies from 0.3/~g22 to 0.8 p.g.9

Infants born to B12 deficient mothers start life with low B12 stores. Such mothers also have low BI2 content in milk (serum content B12 =milk content BI2) 23 and suffer from B12 deficiency megaloblastic anemia during first two years of life. 24 Powdered milk prepared using substan- tial heat, if boiled for reconstitution prior to drinking, lacks B12 and person in whom it is the sole source of animal protein will develop deficiency of BI2. 25

Deficiency of BIe due to diminished absorption can be due to lack of IF or intestinal malabsorption. Gastric parietal cells produce IF. Gastric mucosal defect will decrease IF synthesis. In Pernicious anemia (PA) Blz deficiency results from complete lack of IF due to severe gastric atrophy. Only a few cases described amongst Indians could fit in the definition of PA and that to in some of these atrophic gastritis secondary to tropical sprue could not be excluded. 26 However, in few studies higher incidence of PA has been reported in Indians.2, z7 Pernicious anemia is a geneti- cally determined disease but presence of antibodies against gastric parietal cell cyto plasm, blocking and binding antibodies against IF or IF-BIE complexes and anti- thyroid antibodies suggest an auto-immune disorder. Juvenile PAl?8 of childhood may have etiology similar to adult PA or may be due to selective malabsorption of BI2 (Imerslund's syndrome), congenital lack of IF or production of bio- logically inert IF. Total gastrectomy patients develop megaloblastic anemia in 5-6 years time 29 whereas in those with partial gastrectomy less than 1~o only develop megaloblastic anemia while 2-6~0 have intermediate megaloblastic transfor- mation and 15~o have low serum B12.

SARAYA AND GUPTA : MEGALOBLASTIC ANEMIA 347

These patients also have a low serum iron in contrast to hyperferremia seen with BI2 deficiency from other causes, possibly due to the subsequent atrophy of remain- ing mucosa and decreased iron absorption. 1 Megaloblastic anemia due to gastritis is not uncommon in Indians patients with tropical sprue. 30

Intestinal disorders leading to defective absorption of B12 are listed in Table I. The commonest amongst these in India is tropical sprue. 31 Secondary failure of IF secretion is also found ill one-third of these patients. Localised stasis of intestinal contents (Blind loop syndrome) favours growth of colonic bacteria in the ileum, which complete with the host for B12 and 1F-B~2 complexes. In a similar way fish tapeworm infestation results in BI2 deficiency. Ileal resection, regional ileitis, B12 analogues, megadoses of vitamin C, 32 chronic pancreatitisIS, 16 hypothyroidism and administration of drugs like para aminosalicylic acid, colchicine are other causes of reduction of B12 absorption.

Vitamin BI2 requirements are increased during pregnancy hyperactive, erythro- poiesis and also with hyperthyroidism.

Exposure to anaesthetic gas nitrous oxide cause BI2 deficiency by destroying it.33, 34

Folie acid deficiency

Folate deficiency directly reduces the amount of 5,10 methylene THF available for thymidylate synthesis and results in defective DNA synthesis. Dietary sources of FA include rich sourcesla--liver, yeast (200/~g/100 g), good sources--green vegetables, nuts (50-100 /~g/100 g); moder- ately good sources--some vegetables, fruits, bread, cereals, fish, egg, cheese (10-50 tLg/100 g) and poor sources--rice, milk, meat and chicken (I0 /~g/100 g). Pasteurisation and boiling destroys more than two-third of available relate. Average daily requirement varies from 50-100/Lg. Total body relate stores in an adult are around 10 mg sufficient for only four to five months. 35 Normal serum levels have been varied between 3-20 /~g/l. Red cell and serum relate levels both are important to detect folate deficiency (Table II). Food relates mainly exist in polyglutamate form. These are split to monoglutamate by conSugase enzymes of bile and intestinal secretion. Folate is absorbed as

Table II. Correlation of vitamin B12 and folate levels with clinical status* (Three laboratory tests needed to separate four clinical situations)

Clinical situation Serum vitamin Serum relate Red cell folate Bts pg/ml nglml ng/ml

Normal Normal Nornal (5-16) Normal (> 150) (200-900) Indeterminate (3-5)

or Low (< 3) Vitamin BI~ deficiency Low (< 100) Normal (5--16) Low (< 150)

or High (> 16) Folic acid deficiency Normal Low Low Deficiency of both Low Low Low

*Taken from reference 2.


reduced monoglutamate and partly as oxidized pteroylglutamic acid across the upper third of the small intestine. It is transporated mainly as 5CH 3 T H F to sites of utilisation. In FA deficiency, unaltered folate (nonmethylated THF) appears much earlier (60rain) in circulation. 36 Vitamin Bl2 appears necessary for its cellular uptake and retention, since B12 deficiency results in "pile up" of folate in the serum.

Inadequate dietary intake

Folic acid deficiency develops faster due to low body reserves. Its deficiency compared to BIz deficiency is more in Indian population. Destruction of food folate due to excessive cooking is an important factor. Foetus gains maximum folate from mother during the third tri- mester. 26 Premature infants and infants born to folate deficient mothers and those fed on goat milk or heat sterilised arti- ficial milk suffer from eariy folate deficiency. Indian children with protein calorie malnutrition suffer from folate deficiency megaloblastic anemia. An intrinsic factor in mother 's milk (also cow and other milk) possibly enhances FA absorption in infants.38

Diminished absorption

Deficiency of folate due to intestinal malabsorption is a well known cause. Few cases of congenital folate malabsorption have been described. In these patients folinic acid is more actively transported than FA from the serum into the spinal fluid. It thereby implies that folinic acid is more appropriate for prevention of neurological impairement in this con- dition. 39 Folate is absorbed maximally

from the small intestine. Although sub- total gastrectomy and resection of upper intestine diminish folate absorption, megaloblastic anemia due to folic acid deficiency is not a common feature. Tropical sprue is the second most common cause of megaloblastic anemia in adults due to folate deficiency. 42 Defective polyglutamate absorption, decreased intake due to poor appetite, increased losses from GI tract, increased demand due to rapid intestinal cell turnover, deficiency of an intestinal conjugase, defective absorption, inborn errors of folate metabolism, presence of naturally occurring folate antagonist in the gut and pathogenic enteric microorganisms all contribute to folate deficiency.l, 4~ Other conditions asso~ ciated with FA malabsorption are non- tropical sprue, regional ilietis, lymphoma of small intestine, whipples disease, dia- betes mellitus and anticonvulsant drugs.

lncreased folate requirement

Deficiency due to increased requirement of folate are seen in pregnancy (300 /~g daily)2,26, 43 hyperactive hemopoiesis, skin diseases, neoplasia, chronic infections and diseases like rheumatoid arthritis and cirrhosis. About one-third of pregnant women suffer from dietary FA deficiency. 2 Its prevalence in Indiavaries due to a vari- ety of factors. In south Indian hospitals 60~o pregnant women had megaloblastic bone marrow and 75~o had serum folate below 6 ng/ml/a In a New York clinic 45 two third of the anemic women were deficient in folate and other factors, although only 9~o were deficient in folate alone. In England 46 95~o and in Australia 47 60~o women at term have low serum folate. Association between severe FA defciency and complications of pregnancy

SAKAYA AND GUPTA : MEGALOBLASTIC ANEMIA 349

such as abruptio placentae, embryopatho- logy, spontaneous abortions and bleeding have been suggested.48

Deficiency of folate due to folio acid antagonists and alcohol lead to megaloblastic anemia in spite &concurrent folate administration suggesting antifolate activity or impaired folate utilization.

Management of megaloblastic anemia

Investigations are undertaken to establish the cause of anemia. Treatment is given with the appropriate vitamin and other measures to remedy the underlying cause of deficiency of the vitamin (Bj2 and/or FA). Bed rest is often advisable until the hemoglobin level is about 9 g/ 100 ml. Diet should be well balanced and of high protein and vitamin content. Blood transfusion is seldom indicated unless anemia is severe (5 g/dl) and associated~c~ith intractable cardiovascular symptoms, circuJatory coIIapse, high out- put congestive cardiac failure, severe angina or mental deterioration. If transfusion is unavoidable packed red blood cells should be given slowly. Platelet concen- trates are of value in the rare case with severe thrombocytopenia. Potassium should be supplemented to obviate the danger of hypokalaemia that has been recorded in some patients during initial haematological response.

Vitamin Bl2 therapy

In patients with B12 deficiency therapy is done to correct anemia to arrest oi reverse nervous system lesions when present and to prevent them when absent. Blood morphology should be normal and depleted stores of B12 be corrected in- adequately treated patients. Low cost and lack of toxicity of B12 permits treatment

with large r doses than required: The hydroxycobalmin preparation is preferred. Various regimens are in practice. The following one is recommended. (i) BI2 1000 t,g I.M. daily for 1 to 2 weeks, followed by 1000/~g IM for four weeks or until haematocrit is normal, (ii) 1000/~g monthly for life time of patient, (iii) for- cases of CNS involvement additional 1000 t~g IM every two weeks for 6 months should be given.

Oral BI2 administration is not preferred. Only 17o of oral dose is absorbed in pernicious anemia. Oral administration is indicated in situations when the patient refuses injections, parenteral route may be hazardous as in bleeding disorders and occurrence of hypersensitivity reactions. Very large oral doses are required for therapeutic effect. 300 to 1000 ~g/day may be effective but the response is unpredict- able Depot preparations of BI2 are not employed currently, liver extracts, B12 plus IF are not recommended. Hydro- lysed yeast extracts however, have been recommended for vegetarians. 49

Folate therapy

Precautions to avoid BI2 neuropathy in patients being treated with large doses of FA are exclusion of B12 deficiency and its correction (Table II). To start with oral doses of FA 5 to 15 mg daily are satis- factory. Continue therapy for about four months by which time all folate deficient red cells will be eliminated. Long-term FA is given when the underlying cause of the deficiency cannot be corrected and the deficiency is likely to recur. In such patients it is important to measure the serum B,2 level once a year to exclude coinci- dental development of BI2 deficiency. Prophylactic FA therapy is to be given in


a pregnancy (300 to 400 t~g FA daily) throughout the period of gestation. It should be given to premature babies and to mature babies who require exchange transfusion or develop feeding difficulties, infections or vomiting and diarrhea. Patients of chronic hemolytic anemia and those on long-term hemodialysis should also receive FA. A parenteral preparation containing 15 mg/ml of sodium salt of FA may be used in severely ill patients or in patients incapable of taking oral medications.

Folinic acid is available as a paren- term preparation for use in cases of severe intoxication by FA antagonists that block folate reduction. It may also be more effective in prevention of neurological impairments associated with congenital folate malabsorption since it actively crosses to CSF from the serum.

Megaloblastic anemia unresponsive to vitamin B12 and folic acid

Megaloblastic anemia fails to respond to therapy with Bj2 or FA when caused due to the interference with DNA synthesis by antimetabolite drugs, inborn errors of metabolism and undermined etiology. The fundamental difficulty in all is an inability to duplicate DNA at a normal rate.

L Antimetabolite drugs causing megaloblastic anemia

(i) Inhibitors of purine synthesis (ii) Inhibitors of pyrimidine synthesis (iii) Inhibitors of deoxyribonucleotide

synthesis.

IL Inborn errors qf metabolism associated with megaloblastic anemia

(i) Hereditary orotic aciduria. (ii) Inborn errors of folate metabolism.

III. Unexplained disorders associated with megaloblastic anemia

(i) Pyridoxine responsive megaloblastic anemia.

(ii) Thiamine responsive megaloblastic anemia.

(iii) Refractory anemias (iv) Erythroleukaemia.

Conclusions

The problem of megaloblastic anemia in India basically emanates from B12 deficiency due to nutritional factors and FA deficiency due to infections, inadequate supplementation during pregnancy and prolonged diarrheal disorders, be- sides other etiological factors that would be common to this country and the developed world. To establish diagnosis of megaloblastic anemia peripheral blood and bone marrow examination is a neces- sity. Estimation of serum B12, folate and red cell folate is an additional evidence that would corroborate a deficiency of these vitamins as etiological factor. In patients of megaloblastic anemia, however, the inadequate facilities and extent of the problem are true limitations to advocate these estimations as part of investigations scheduled for its diagnosis. It is recommended that a therapeutic trial with BI2 followed by FA in cases where the former patients do not respond be carried out to establish the etiology of the disease and further investigations be carried out to elucidate the basic pathogenetic mechanism responsible for vitamin deficiency. The reticulocyte count done between 3rd and 7th day and at the peak on 5th day of the treatment and hemoglobin estimation after one week would establish the responsiveness to the vitamin employed for the trial. Caution however, has to be


exercised that seriously ill patients are no t put to the therapeut ic trials as it enhances the r isk to their lives. Severe anemia , angina pectoris, neurological disease, congestive cardiac disease and bleeding are contra- indicat ions for conduct ing a thera-

peutic trial. Such pat ients should be m a n a - ged symptomat ica l ly and at tempt should be made to increase the hemoglob in levels

by packed red cell t ransfus ions and there- after the regular therapy with B12 be insti tuted and if the responses is absent

or inadequate, F A be added. If the rise in hemoglobin level with Bi2 therapy ini- tially is good but if no rma l i s a t i on of hemoglobin does not take place, a reas- sessment would be necessary to exclude deficiency or i ron as a l imit ing factor.

Folic acid therapy should be ins t i tu ted

along with B12 therapy in the absence of concurrent i ron deficiency.

References

1. Beck SW. Erythrocyte disorders-anemias related to disturbance of DNA synthesis (megaloblastic anemias) In : William J Williams, Beutler E, Erslev AJ, Lichtman MA eds. Haematology 3rd edn. McGraw-Hill Book company 1983; 436-465

2. Herbert V. Megaloblastic anaemias. Lab Invest 1985; 52 : 3-19

3. Killmann SA. Effects of deoxyuridine on in- corporation of tritiated thymidine. Difference between normoblasts and megaloblasts. Aeta Med Scand 1964; 175 : 483-488

4. Beck SW. Metabolic features of cobalmin deficiency in man. In Cobalmins : Bioehe- mistry and pathophysiology ed. BM Babior Wiley-interscience. New York 1975 p 403

5. Hoffbrand AV, Wickremasinghe RG. Mega- loblastic anaemia. I n : Hoffbrand AV, ed. Recent advances in haematology. No. three Churchill Livingstone. The Pitman Press, Bath, 1982:25-44

6. Taheri R, Wickremasinghe RG, Hoffbrand AV. Alternative metabolic fates of thymine nucleotides in human cells. Bioehem J 1981; 194 �9 451-461

7. William SB. Megaloblastic anaemia in Cecil Textbook of medicine. James B, Wynaggar- den & Lloyd H Smith JR ed. Philadelphia : W.B. Saunders Company 1985; 893-899

8. Scott JM, Dinn J J, Wilson P, Weir DG. Pathogenesis of subaeute combined degene- ration : a result of methyl group deficiency. Lancet 1981:2 : 334-337

9. Chanarin 1. The megaloblastie anaemias 2nd ed. Oxford : Blackwell 1979.

10. Grasbeck R. Calculations on vitamin Bja turnover in man. Stand J Clin Lab Invest 1959; 11 : 250-258

11. Saraya AK, Choudhry VP, Ghai PP. Interre- lationships of vitamin B12, folio acid and iron in anaemia of infancy and childhood : effects of vitamin Bte and iron therapy on folate metabolism. Am J Clin Nutr 1973; 26:640-646

12. Saraya AK, Singla PN, Ghai OP, Ramchan- dran K. Nutritional Macrocytic anaemia of infancy & childhood. Am J Clin Nutr 1970; 23 : 1378-1384

13. Saraya AK, Choudhary VP, Ghai PP. Rela- tive roles of iron, vitamin B12 and folic acid deficiency in macrocytic anaemia in, infancy and childhood. J AIIMS 1977; 3 : 65-72

14. Saraya AK. Nutritional Anemia. In : Ahuja MMS ed. Progress in Clinical Medicine in India. Second series. New Delhi, Arnold Heinemann 1978:534-569

15. Brugg WR, Goff JS, Allen NG, Podell ER, Allen RH. Development of a dual label schilling test for pancreatic exocrine function based on the differential absorption of cobalmin bound to intrinsic factor and R protein. Gastroenterology 1980; 78 : 937-949

16. Allen RH, Seetharam B, Allen NC, PodeU ER, Alpers DH. Correction of cobalamin malabsorption in pancreatic insufficiency with a cobalamin analogue that binds with high affinity to R protein but not to intrinsic factor, J Clin Invest 1978; 61 : 1628-1634

17. Herzlich B, Herbert V. The role of pancreas in cobalamin (Vitamin Bt2) absorption. Am J Gastroenterol 1984; 79 : 489-493

18. Kanazawa S, Herzlich B, Herbert V. Enhan- cing effect of human bile on the uptake of free vitamin Blz and intrinsic factor-Bt2 by receptors on the small bowel epithelial-cells (abstr.) Blood 1982; 60 (Suppt. I) : 309

19. Jacob E, Baker S J, Herbert V. Vitamin B12 binding proteins. Physiol Rev 1980; 60 : 918- 960

352 THE INDIAN JOURNAL OF PEDIATRICS Vol. 54. No. 3

20. Kanazawa S, Herbert V, Herzlick B, Drivas G, Manusselis C. Removal of cobalmin analogue in bile by enterohepatic circulation of vitamin B~. Lancet 1983; I : 707-708

21. Chanarin I, Malkowska V, Marie O' Hea A, Rinsler MG, Price A B. Megaloblastic anaemia in a vegetarian Hindu community Lancet 1985; 2 : 1168-1172

22. Abdulla M, Anderson I, Asp N-G et al. Nutrient intake and health status of vegans. Chemical analysis of diets using the duplicate portion sampling technique. Am J Clin Nutr 1981; 34 : 2464-2477 p

23. Baker S J, Jacob E, Rajan KT, Suaminathan SP. Vitamin B~2 deficiency in pregnancy and puerperium. Br Med J 1962; 1 : 1658-1661

24. Jadhav M, Webb JKG, Vaishnana S, Baker SJ. Vitamin Br2 deficiency in Indian infants : A clinical syndrome. Lancet 1962; 2 : 903-907

25. Herbert V, Manusselis C, Drivas G, Colman N. Low Vitamin Bx~ content of heavily pro- cessed milk may explain vitamin Blo " deficiency in young adults in Mexico (abstr). Clin Res 1983;31 : 241A

26. Baker SJ. Megaloblastic Anaemia. In : Ahuja MMS, ed. Progress in clinical medicine in India. Series First. New Delhi. Arnold Heine- mann Publishers. 1981; 420-444

27. Mathews JH, Wood JK Megaloblastic anaemia in vegetarian Asians. Clin Lab Haematol 1984; 6 : 1-7

28. Spurling CL, Sacks MS, Jiji RM. Juvenile pernicious anemia. N Engi J Med 1964; 271 : 995-1003

29. Maclean LD, Sunberg RD. Incidence of megaloblastic anemia after total gastrectomy. N Engl J Med 1956; 254 : 885-93

30. Vaish SK, Sampath Kumar J, Jacob R, Baker SJ. The stomach in tropical sprue. Gut 1965; 6 : 458-465

31. Baker SJ. Tropical megaloblastic anaemia. Indian J Pathol Bact 1958; 1 : 11-26

32. Herbert V, Jacob E, Wong KT, Scot J, Pfeffer R. Low serum vitamin Bx~ - levels in patients receiving ascorbic acid in megadoses : Studies concerning the effect of ascorbate on radio- isotope vitamin B12 assay. Am J Clin Nutr 1978; 31 : 253-258

33. Deacon R, Lumb M, Perry J, Chanarin I, et al. Selective inactivation of vitamin B12 in rats by nitrous oxide. Lancet 1978; 2 : 1023- 1024

34. Chanarin I. Cobalamins and nitrous oxide : A review. J CUn Pathol 1980; 33 : 909-916

35. Herbert V. Experimental Nutritional folate deficiency in man. Trans Assoe Am Physns 1962; 75 : 307-20

36. Saraya AK. Interrelationship of vitamin Bt,, , folio acid and iron in anaemia of infancy and childhood : Folate distribution and dynamics in iron deficiency. Plenary session of third meeting of the Asian-Pacific Division of Haematology Programme 1975. p 34

37. Pereira SM, Baker SJ. Haematologic studies in kwashiorkar. Am J Clin Nutr 1966; 18 : 413-420

38. Colman N, Hettiarachchy N, Herbert V. Detection of a milk factor that facilitates folate uptake by intestinal cells. Science 1981 ; 211 : 1427-1429

39. Poncz M, Colman N, Hert V et al. Therapy of congenital folate malabsorption. J Pediatr 1981; 98 : 76-79

40. Baker S J, Mathen VI. Tropical sprue in southern India. In Tropical spure--A Wellcome Trust Collaborative Study. Churchill, London 1971

41. Jeejeebhoy KN, Desai HG, Borker AV et al. Tropical malabsorption syndrome in West India. Am J Clin Nutr 1968; 21 : 994-1006

42. Butterworth CE. Tropical sprue : A consi- deration of some possible aetiological mecha- nisms in malabsorption, edited by R.H. Girdwood and A.N. Smith. Pfizer Medical Monograph 4 Edinburgh : University of Edinburgh Press, 1969 p 238

43. Willoughby ML. An investigation of folio acid requirements in pregnancy. II. Br J Haemat 1967; 13 : 503-509

44. Yusufji D, Mathan UI, Baker SJ. Iron, folate and vitamin B12 nutrition in pregnancy : A study of 1000 women from southern India. Bull WId HIth Org 1973; 48 : 15-22

45. Benjamin F, Bassen FA, Mayer LM. Serum levels of folio acid vitamin B12 and iron in anaemia of pregnancy. Am J Obstet Gynec 1966; 96 : 310-315

46. Ball EW, Giles C. Folio acid and vitamin Bx2 levels in pregnancy and their relation to megaloblastic anemia. J CUn Pathol 1964; 17 : 165-174


47. Whiteside MG, Ungar B, Cowling DC. Iron, folic acid and vitamin Blo " levels in normal pregnancy and their influences on birth weight and duration of pregnancy. Med J Aust 1968: ! : 338-342

48. Streiff RR, Little AB. Folic acid deficiency in pregnancy. 1N Eagi J Med 1967; 276 : 776-779

49. Tylden E. Tropical macroeytic anemia. Lancet 1986; 1 : 94-95

ETHAMSYLATE FOR PREVENTION OF PERIVENTRICULAR H E M O R R H A G E IN LOW B I R T H W E I G H T INFANTS

rhe effectiveness of ethamyslate in the prevention of periventricular hemorrhage (PVH) in very low birthweight infants was evaluated by means of a multicentre, placebo- controlled, double-blind trial. In 330 infants without evidence of PVH on initial cranial ultrasound examination there was little difference between ethamyslate and placebo groups with respect to subependymal haemorrhage, but intraventricular and parenchy- real haemorrhages developed in 30/162 infants (18 .5~) in the treated group, compared with 50/168 (29 .8~) in the control (P<0 .05 ) . In 30 infants with evidence of PVH on the initial scan, ethamsylate treatment seemed to limit parenchymal extension. Analysis of the total cohort of 360 infants showed that the proportion of infants in whom an increase of two or more grades of severity of PVH was recorded during the trial was lower in the treated than in the placebo group (P<0 .01) . No adverse effects were attri- buted to ethamsytate therapy. The reported incidence of paten ductus arteriosus was lower in the treated than in the placebo group (P<0 .02) . Mortality was similar in the two groups.

In conclusion, ethamsylate reduced the incidence and severity of periventricular hemorrhage in very low birthweight infants when given soon after birth for 4 days. The effect was seen mainly on the more extensive grades of haemorrhage, which are more likely to produce later neurological deficit. Neurodevelopmental follow-up of the sur- viving infants from this trial is planned. There was also a potentially useful reduction in the reported frequency of patent ductus arteriosus during the trial period. Renal failure occurred less often in the ethamsylate group, perhaps a reflection of the lower incidence of PVH. No unwanted side-effects were noted. Ethamyslate prophylaxis in the con- junction with improvements in neonatal intensive care should improve the outlook for very low birthweight infants.

Abs t rac t ed fronT : Benson JWT et al. Lancet 1986; ii : 1297-1300.

Documents

Megaloblastic anemia—etiology and management