description about introduction, epidemiology, etiology, pathophysiology and treatment.

1. Assignment on: Megaloblastic Anemia
Subject: Clinical Pharmacy and drug Interaction
Course Code: PHA:585
Submitted by Submitted to
Ravi Rastogi Dr. Pushpraj S Gupta
16BPH081 Department of pharmaceutical science
B. Pharmacy (8th sem.) FHS, SIHAS, SHUATS

2. Acknowledgment
I have tried my best for preparing this
assignment. However, it was almost impossible
without kind support of my teacher, classmates
and seniors.
First of all, I am very thankful to our subject
teacher Dr. Pushpraj S Gupta for giving us this
opportunity to enhance our knowledge and
learn new things.
Similarly, I’d like to thank all my batchmates
for their continuous help and support to
complete this assignment.

3. Contents
Introduction
Epidemiology
Etiology
 Major causes of cobalamin deficiency include
 Major causes of folate deficiency
 Other causes for megaloblastosis
Pathophysiology
Diagnosis
 Specific diagnostic tests for folate and cobalamin deficiency
Treatment
 Therapeutic treatment
 Folic acid deficiency
 Cobalamin deficiency
 Monitoring Response to Therapy
 Non- Therapeutic Treatment
 Dietary Measures
 Vitamin B-12 Deficiency
 Folate Deficiency
 Treatment of Other Related Conditions
Conclusion
References

4. 1. Introduction
Megaloblastic anemia (MA) is a distinct type of anemia characterized by macrocytic RBCs
and typical morphological changes in RBC precursors. The RBC precursors are larger than
the cells of same stage and exhibit disparity in nuclear-cytoplasmic maturation. Basic
underlying pathogenetic mechanism in MA is deficiency of folic acid (FA) and/or vitamin
B12 at the cellular level with resultant impairment of DNA synthesis. In developing
countries, most cases of MA result from nutritional deficiency of these micronutrients.
Other than MA, deficiency of these hematopoietic micronutrients in children has been
incriminated to cause neuro-developmental dysfunction, abnormal movements and failure
to thrive. Neural tube defects result from deficiency of folate in mothers during pregnancy.
Because of these ill effects, folate has since long been included in the supplementation
programs to control anemia. At community level most cases of nutritional anemia result
from deficiency of iron and can be prevented or treated with iron administration. From
public health viewpoint, deficiency of folate and B12 has been regarded to contribute little
to nutritional anemia. Over the last two decades, role of these micronutrients and their
deficiency has been brought to the forefront by various workers. Presentation of patients
with MA with pancytopenia, vasculo-toxic effects of hyperhomocysteinemia resulting
from folate and/ or B12 deficiency and possible role of their deficiency in causing bone
loss leading to osteopenia, osteoporosis and pathological fractures has brought B12 and
folate deficiency and MA back in focus.
Figure: Diagnosed as megaloblastic anemia of Peripheral blood smear
2. Epidemiology
Epidemiological studies on megaloblastic anemia in Nigeria and in Africa are sparse.
However, the frequency of megaloblastosis is highest in countries in which malnutrition is

5. rampant and routine vitamin supplementation for elderly individuals and pregnant woman
is not available. Faulty preparations of foods and increased demand for folate during
pregnancy are the most common causes of megaloblastic anemias. About 1 in 7500 people
develops pernicious anemia in the US per year but this has been modified by current
fortification of foods and vitamin supplementations in elderly patients in the US.
International statistics showed that pernicious anemia and folate deficiency usually occur
in individuals older than 40 years and the prevalence increases with older populations. The
incidence of pernicious anemia is reported to be higher in Sweden, Denmark, and United
Kingdom than in other developed countries.
3. Etiology
The principal causes of megaloblastic anemia in clinical practice are folate and cobalamin
deficiency either directly or indirectly as sone in given table No.1
Cobalamin
deficiency
Folate deficiency Drug-induced
suppression of
DNA synthesis
Inborn errors
1 Dietary deficiency
2 Deficiency of
gastric IF Pernicious
anemia or
gastrectomy
3 Intestinal
malabsorption
Ileal resectionor
ileitis
Familial selective
cobalamin
malabsorption
Competitive parasites
or infections
Fish tapeworm
Bacteria overgrowth
in malformed small
bowel
1 Dietary
deficiency
2 Impaired
absorption Sprue
Extensive small
bowel disease or
resection
Intestinal short
circuits
Anticonvulsants
and oral
contraceptives
3 Increased
requirements
Pregnancy
Hemolytic anemia
Myeloproliferative
and other
1 Folate antagonists
2 Metabolic
inhibitors of purine
pyrimidine
thymidylate
synthesis Other
inhibitors
3 Alkylating agents
D. Nitrous oxide
4 Inborn errors
 Defective
transport of
cobalamin
 Defective
cobalamin
utilization
 Defective
folate
metabolism
 Hereditary
orotic
aciduria
1 Defective
transport of
cobalamin
2 Defective
cobalamin
utilization
3 Defective folate
metabolisms
4 Hereditary orotic
aciduria
E. Lesch-Nyhan
syndrome

6. 4 Increased
Requirement
hyperproliferative
disorders
 Lesch-
Nyhan
syndrome
3.1. Major causes of cobalamin deficiency include
Dietary: Dietary cause of cobalamin deficiency is rare except in strict vegetarians who
avoid taking meat, eggs, and dairy products.
Problems with cobalamin absorption: Atrophic gastritis and achlorhydria, which
commonly occur in elderly people are the two conditions which are responsible for
impaired release of cobalamins bound to food. Hence, cobalamin is not released from food
for absorptive process.
Also, autoimmune destruction of gastric parietal cellsmay lead to failure of intrinsic factor
production. This condition is called pernicious anemia. Pernicious anemia is recognized as
the best-known cause of cobalamin deficiency. It is diagnosed in 1% of people older than
60 years and the incidence is slightly higher in women than in men.
Inhibition of intrinsic factor production can also be caused by H2 antagonists. The release
of cobalamin from R-proteins can also be inhibited by the alkaline environment in the small
intestine emanating from pancreatic insufficiency.
On the contrary, the acidic environment seenin conditions like Zollinger Ellison syndrome,
also prevents binding of cobalamin to intrinsic factor hence leading to diminished binding
to intrinsic factor and ultimate interference with cobalamin absorption.
The disorders of the terminal ileum, site of uptake of cobalamin-intrinsic factor complex,
can cause cobalamin deficiency. Disorders that can possibly affect the terminal ileum
include tropical sprue, inflammatory bowel disease, lymphoma, as well as ileal resection.
Autoimmune destruction of the ileal receptor, cubilin, as found in Imerslund Grasbeck
syndrome equally distrupts the uptake ofcobalamin bound to intrinsic factor. Also, bacteria
colonization can occur in intestines deformed by strictures, surgical blind loops,
scleroderma, inflammatory bowel disease, or amyloidosis blind loop syndrome can result
to I. Cobalamin deficiency II. Folate deficiency III. Drug-induced suppression of DNA
synthesis IV. Inborn errors (i) Dietary deficiency (ii) Deficiency of gastric IF Pernicious
anemia or gastrectomy (iii) Intestinal malabsorption Ileal resection or ileitis Familial
selective cobalamin malabsorption Competitive parasites or infections Fish tapeworm
Bacteria overgrowth in malformed small bowel (iv) Increased Requirement (i) Dietary
deficiency (ii) Impaired absorption Sprue Extensive small bowel disease or resection
Intestinal short circuitsAnticonvulsants and oral contraceptives (iii)Increased requirement
Pregnancy Hemolytic anemia Myeloproliferative and other hyperproliferative disorders (i)

7. Folate antagonists (ii) Metabolic inhibitors of purine pyrimidine thymidylate synthesis
Other inhibitors (iii) Alkylating agents D. Nitrous oxide (IV) Inborn errors a. Defective
transport of cobalamin b. Defective cobalamin utilization c. Defective folate metabolism
d. Hereditary orotic aciduria e. Lesch-Nyhan syndrome (i) Defective transport of
cobalamin (ii) Defective cobalamin utilization (iii) Defective folate metabolism (iv)
Hereditary orotic aciduria E. Lesch-Nyhan syndrome Table 1. Pathogenetic classification
of megaloblastic anemia. 32 Current Topics in Anemia cobalamin deficiency. In this
condition, bacteria compete with the host for cobalamin for the uptake of cobalamin bound
to intrinsic factor.
Fish tapeworm such as Diphyllobothrium latum infestation, which is common in places
like Canada, Alaska, and the Baltic sea, feeds on cobalamin in the intestine thereby
reducing the amount of cobalamin available for ingestion by the host.
Miscellaneous causes of cobalamin deficiency include exposure to nitrous oxide, which
through oxidative inactivation of cobalamin causes megaloblastosis. Prolonged exposure
to nitrous oxide can lead to severe mental and neurological disorders. Various medications
like purine analogs (six mercaptopurine, six tioguanine), pyrimidine analogs (five
fluorouracil and five azacytidine), and drugs that affect cobalamin metabolism like P-
aminosalicylic acid, phenformin, and metformin that can cause cobalamin deficiency.
3.2. Major causes of folate deficiency
The main cause of loss of folate from food is poor food preparation through excessive
dilution of food in water, through excessive heating, and subsequent inactivation of folate
since folate is thermolabile. However, food fortificationwith folate and other vitamins are
circumventing this problem in developed countries. This has to be aggressively promoted
in many developing countries.
The storage of folate is for about 4 weeks after which folate deficiency sets in if folate
intake is stopped. The daily requirement for adult is about 0.4 mg/day. Folate deficiency
occurs in situations where there is impaired absorption due to certain intestinal disorders
like tropical sprue, nontropical sprue (celiac disease), amyloidosis, and inflammatory
bowel disease.
Folate deficiency occurs in situations where there is increased physiologic demand for
folate like chronic hemolytic states like sickle cell anemia, hereditary spherocytosis, and
elliptocytosis;pregnancy, lactation, rapid growth, hyperalimentation, renal dialysis, where
there is escalated loss of rapidly dividing cells like psoriasis and exfoliative dermatitis.
Also, medications such as phenytoin, metformin, phenobarbitone, dihydrofolate reductase,
folate inhibitors like trimethoprim and pyrimethamine, methotrexate, sulphonamides, can
cause folate deficiency.

8. Megaloblastic changes in human immunodeficiency virus (HIV) infection and
myelodysplastic disorders are due to direct effect on deoxyribonucleic acid (DNA) in
hemopoietic and other rapidly dividing cells.
3.3. Other causes for megaloblastosis
Megaloblastosis in HIV infectionand myelodysplastic disorders is due to a direct effect on
DNA synthesis in hematopoietic and other cells.
4. Pathophysiology
The two vitamins, that is, folate and cobalamin act synergistically in generating the
thymidylic acid used for DNA synthesis. Therefore, in cobalamin deficiency, the
megaloblastic arrest is actually caused by a deficit in folate utilization. As shown in Figure
1 (activated methyl cycle), methionine is generated by transfer of methylene group from
N5-methyl tetrahydrofolate (FH4) to homocysteine using the enzyme methyl transferase
(Methionine synthase). In this biochemical process, methylcobalamin is the factor that
assists in methyl transfer as coenzyme form of cobalamin. This is why the morphological
abnormalities emanating from either cobalamin or folate deficiency appear exactly alike.
dUMP dTMP DNA
Methylene FH4 FH2
Methyl FH4 FH4
Homocysteine Methionine
VitaminB12

9. 5. Diagnosis
One test used to diagnose many forms of anemia is the complete blood count (CBC). This
test measures the different parts of your blood. Your doctor can check the number and
appearance of your red blood cells. They will appear larger and underdeveloped if you have
megaloblastic anemia. Your doctor will also gather your medical history and perform a
physical exam to rule out other causes of your symptoms. Your doctor will need to do more
blood tests to figure out if vitamin deficiency is causing your anemia. These tests will also
help them find out whether it’s a vitamin B-12 or folate deficiency that’s causing the
condition.
One test that your doctor may use to help diagnose you is the Schilling test. The Schilling
test is a blood testthat evaluates your ability to absorb vitamin B-12. After you take a small
supplement of radioactive vitamin B-12, you’ll collect a urine sample for your doctor to
analyze. You will then take the same radioactive supplement in combination with the
“intrinsic factor” protein that your body needs to be able to absorb vitamin B-12. Then
you’ll provide another urine sample so it can be compared to the first one. It’s a sign that
you don’t produce intrinsic factor of your own if the urine samples show that you only
absorbed the B-12 after consuming it along with the intrinsic factor. This means that you’re
unable to absorb vitamin B-12 naturally.
Specific diagnostic tests for folate and cobalamin deficiency
Laboratory studies and diagnostic ranges Situations affecting results
Serum folate
<2 ng/mL is diagnostic
>4 ng/mL rules out deficiency
2---4 ng/mL = quantify methylmalonic
acid and homocysteine
Falselylow: Pregnancy, alcohol
consumption, anti-seizure drugs,
temporarily (a few days) deficient diet
(with normal intra-enterocyte folate).
Falselyelevated: Single intake of
folate-rich food.

10. Intra-enterocyte folate
(methyltetrahydrofolate [MTHF] and
formyltetrahydrofolate (FTHF]
<100---160 mg/L = deficiency
63% of patients with cobalamin
deficiency have low erythrocyte folate
levels.
Compared with serum folate, less likely
to alter due to
transient variations such as dietary
changes.
Serum cobalamin
<200 pg/mL diagnostic of deficiency
>300 pg/mL rules out deficiency in 95%
of cases
200---300 pg/mL = quantify
methylmalonic acid and homocysteine
Intra-individual variation: up to 23%
Methylmalonic acid (MMA)
Normal: 70---270 mmol/L
Intra-individual variation: up to 23%
Usually elevated with comorbid cobalamin
deficiency
Homocysteine
Normal: 5---14 mmol/L
Intra-individual variation: 17%
Usually elevated with comorbid cobalamin
and folate
deficiency
Falselylow: Pregnancy, alcohol
consumption, anti-seizure drugs,
temporarily (a few days) deficient diet
(with normal intra-enterocyte folate).
Falselyelevated: Single intake of
folate-rich food.
Falselylow: Pregnancy, folate
deficiency, HIV/Aids, anti-seizure
drugs, multiply myeloma, hairy cell
leukaemia, aplastic anaemia,
myelodysplastic syndromes, paroxysmal
nocturnal haemoglobinuria, Gaucher’s
disease, oral contraceptives, idiopathic
origin, laboratory error.
Falselyelevated: Kidney failure,
methylmalonic acidaemia.
Falselylow: Use of antibiotics.
Falselyelevated: Hereditary
hyperhomocysteinaemia: changes in
methyl-THFR, cystathionine beta-
synthase, betaine synthesis.
Note:
 Elevated MMA and homocysteine: cobalamin deficiency (sensitivity: 94%,
specificity: 99%).
 Normal MMA and homocysteine: rule out deficiency of both vitamins.

11.  Normal MMA and elevated homocysteine: folate deficiency (sensitivity: 86%,
specificity: 99%).
5. Treatment
5.1. Therapeutic Treatment
A. Folic acid deficiency
Before starting treatment for megaloblastic anaemia due to folic acid deficiency, it is
important to ascertain the absence of concomitant cobalamin deficiency, and even to
establish that cobalamin deficiency is not, in fact, the sole pathogenesis. When folates are
given to a patient with cobalamin deficiency as the sole cause of the anaemia, or when both
folic acid and cobalamin deficiency are involved, the blood picture will improve but
neurological manifestations will worsen. High-dose, oral supplements should be given. See
Fig.2 for an overview of pharmacological management.
B. Cobalamin deficiency
As in the case of folate deficiency, cobalamin deficiency therapy should continue until
blood levels return to normal, or the underlying condition is resolved. The best route of
administration is intramuscular. Excess cobalamin is excreted in the urine. Recent studies
suggest that oral cobalamin is a safe and effective alternative, even in patients with low
intrinsic factor levels. In patients that respond well to oral cobalamin, treatment should
continue indefinitely at a dose of 1000 mcg/day 9 as Fig. 2)

12. Figure 2: Pharmacological management of megaloblastic anaemia
5.2. Monitoring Response to Therapy
Although patients may feel better as soon as therapy is started, improvements must be
monitored with. Laboratory tests to order include the following:
 Complete blood cell count
 Reticulocyte count
 Lactate dehydrogenase (LDH) level
 Indirect bilirubin
 Hemoglobin level
 Serum potassium level
 Serum ferritin

13. Elevated levels of LDH and indirect bilirubin should fall rapidly. A prolonged elevation of
the LDH level indicates a failure of therapy, development of iron deficiency, or an error in
diagnosis.
Reticulocytosis should be evident within 3-5 days and peaks in 4-10 days. Leukocyte and
platelets counts are usually restored to normal within days after therapy has been started,
but hypersegmented neutrophils may persist for 10-14 days.
The hemoglobin should rise approximately 1 g/dL each week. This rise is valuable for
monitoring a complete response. If the hemoglobin does not rise appropriately and is not
normal within 2 months, other causes of anemia, such as iron deficiency, should be
considered.
Serum potassium levels can fall during therapy for severe cobalamin or folate deficiency
and can lead to sudden death. Therefore, potassium should be monitored and supplements
may be indicated.
Iron deficiency can occur in the course of treatment due to the consumption of iron stores
for RBC production. The development of iron deficiency can impede the response to
cobalamin or folate therapy. Iron therapy may be indicated.
5.3. Non- Therapeutic Treatment
5.3.1. Dietary Measures
A. Vitamin B-12 Deficiency
Foods that have vitamin B-12 in them include:
 eggs
 chicken
 fortified cereals (especially bran)
 red meats (especially beef)
 milk
 shellfish

14. A. Folate Deficiency
Dietary changes also help boost folate levels. Foods to include in your diet include:
 oranges
 leafy green vegetables
 peanuts
 lentils
 enriched grains
5.4. Treatment of Other Related Conditions
Other related conditions, if present, should be addressed as follows:
 Blind loop syndrome should be treated with antibiotics.
 Patients with transcobalamin II (TCII) deficiency may require higher doses of
cobalamin.
 Tropical sprue should be treated with both cobalamin and folate.
 Acute megaloblastic anemias due to nitrous oxide exposure can be treated with
folate and cobalamin.
 Fish tapeworm infection, pancreatitis, Zollinger-Ellison syndrome, and inborn
errors should be treated with appropriate measures.
Conclusion
It is very obvious that there is “resurgence” on folate-B12 deficiency/MA over the last two
decades. This clearly reflects renewed interest in the subject as more and more cases are
being seen in clinical practice. The phenomenon appears to be widespread. Many
developing countries like India have anemia control prophylaxis programs and in addition
there is overall improvement in general standard of living. In light of these facts, the causes
for increased incidence of folate-B12 deficiency and /or MA needs to be elucidated. As
pointed out earlier, over the last few yrs., B12 deficiency has taken over as more common
micronutrient deficiency as compared to folate. Even this shift needs to be explained. Role
of malabsorption and within country population migration towards urban areas
contributing to diminished endogenous B12 synthesis needs to be elucidated.

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