ATA 641-PART 2 BOĞAZİÇİ UNIVERSITY 2007 Prof. Dr. Zafer Toprak
International Journal of Laboratory Hematology (Blackwell) Volume 36 Issue 4 2014 [Doi...
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8/19/2019 International Journal of Laboratory Hematology (Blackwell) Volume 36 Issue 4 2014 [Doi 10.1111_ijlh.12158] Topra…
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Vitamin B12 and folate deficiency: should we use a different
cutoff value for hematologic disorders?
B. TOPRAK, H. Z. YALCIN, A. COLAK
Department of Clinical
Biochemistry, Tepecik Training
and Research Hospital, Izmir,
Turkey
Correspondence:
Burak Toprak, Department of
Clinical Biochemistry, TepecikTraining and Research Hospital,
Gaziler Cad., No:468, Yenisehir,
Izmir 35183, Turkey.
Tel.: +90-232-4696969;
Fax: +90-232-4330756;
E-mail: [email protected]
doi:10.1111/ijlh.12158
Received 27 August 2013;
accepted for publication 12 Sep-
tember 2013
Keywords
Anemia, B12, cutoff value,
folate, macrocytosis
S U M M A R Y
Introduction: Anemia and macrocytosis are well-defined expected
hematologic findings of vitamin B12 and folate deficiency; how-
ever, some previous studies did not show a significant association
of subnormal B12 with anemia and macrocytosis.
Methods: We retrospectively analyzed 17 713 laboratory patientrecords to evaluate vitamin B12 and folate levels in relation to
anemia and macrocytosis.
Results: In an age- and sex-adjusted logistic regression model, low
B12 status but not marginal B12 status was significantly associated
with anemia [ORs respectively, 1.291 (95% CI, 1.182 – 1.410),
1.022 (95% CI, 0.943 – 1.108)] and macrocytosis [ORs, respectively,
3.853 (95% CI, 3.121 – 4.756), 1.031 (95% CI, 0.770 – 1.381)]. Also
low folate status but not marginal folate status was significantly
associated with anemia [adjusted ORs, respectively, 1.819 (95% CI,
1.372 – 2.411), 1.101 (95% CI, 0.931 – 1.301)] and macrocytosis
[adjusted ORs, respectively, 2.945 (95% CI, 1.747 – 4.965), 1.228
(95% CI, 0.795 – 1.898)].
Conclusion: Our results show that increased anemia and macrocyto-
sis are observed at values below commonly used B12 lower-refer-
ence thresholds. Determining a hematologic cutoff value may help
physicians in clinical practice.
IN T R O D U C T IO N
Vitamin B12 and folate are important cofactors in the
DNA synthesis. Deficiency of both of these water solu-
ble vitamins is frequent health problems particularly
in the elderly [1, 2]. Common causes of cobalamin
deficiency are food-cobalamin malabsorbtion, perni-
cious anemia, and dietary deficiency [3 – 6]. A number
of biomarkers have been used for cobalamin defi-
ciency diagnosis, including serum cobalamin,
methylmalonic acid (MMA), homocystein, and holo-
transcobalamin II. The most common biomarker used
for diagnosis is serum cobalamin. Older studies used
lower cobalamin cutoff values
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therefore, usage of higher cobalamin cutoff values
was suggested by some authors for improvement of
sensitivity [9]. Vitamin B12 deficiency is associated
with hematologic and neurologic abnormalities.
Hematologic manifestations of cobalamin deficiencyinclude anemia, macrocytosis, pancytopenia and neu-
trophil hypersegmentation [10 – 14]. The effect of
cobalamin deficiency on hematopoiesis is documented
in the literature [15, 16], and the association between
pernicious anemia and cobalamin deficiency is well
known, but studies about hematologic response to
B12 treatment is inconsistent [10, 17 – 24]. Some stud-
ies failed to demonstrate a significant hematologic
response to cobalamin therapy [17 – 22].
The reasons for folate deficiency are reduced
intake, malabsorbtion, increased metabolism, and
increased requirements. Folate deficiency is associated
with megaloblastic anemia mood disorders and neural
tube defects [25]. The lower limit of the reference
range for serum folate is usually set at about 6.8 nM
(3 ng/mL) [26]. Some studies defined 200 pg/mL). Folate
levels were classified as low (≤2.2 ng/mL), marginal(2.2 – 3 ng/mL) and normal (>3 ng/mL). World Health
Organization criteria (hemoglobin 200 pg/mL (148 pM) and folate >3 ng/mL
(6.8 nM) were considered as reference and age- and
gender-adjusted ORs of marginal and low b12, and
folate status for anemia and macrocytosis was esti-
mated. To investigate the effect of age on vitamin B12
and folate deficiency, age groups (18 – 50, 51 – 60,
61 – 70, 71 – 80, 80 – 85) were generated. ORs of age
groups for low cobalamin and folate status were esti-
mated using logistic regression analyses. The age
group 18 – 50 was reference.
RESULTS
A total of 17 713 vitamin B12, folate, hemoglobin,
and MCV results were investigated. There were12 870 female and 4843 male subjects. The results
show that 14.7% of the subjects have vitamin
B12 ≤ 150 pg/mL (111 pM) and 34.1% have vitamin
B12 ≤ 200 pg/mL (148 pM). Only 1.1% of the subjects
have folate ≤2.2 ng/mL (5 nM) and 4.7% have folate
≤3.0 ng/mL (6.8 nM). There were 35% anemic sub-
jects, and 2.5% of the subjects have macrocytosis
(Table 1).
In an age- and sex-adjusted logistic regression
model, low B12 status but not marginal B12 status
was significantly associated with anemia [ORs, respec-
tively, 1.291 (95% CI, 1.182 – 1.410), 1.022 (95% CI,
0.943 – 1.108)] and macrocytosis [ORs, respectively,
3.853 (95% CI, 3.121 – 4.756), 1.031 (95% CI, 0.770 –
1.381)]. Low B12 status and marginal B12 status were
significantly related to male sex [age-adjusted ORs,
respectively, 1.300 (95% CI, 1.183 – 1.427), 1.134
(95% CI, 1.041 – 1.237)] (Table 2).
Also low folate status but not marginal folate status
was significantly associated with anemia [adjusted
© 2013 John Wiley & Sons Ltd, Int. Jnl. Lab. Hem. 2014, 36, 409–414
410 B. TOPRAK, H. Z. YALCIN AND A. COLAK | VITAMIN B12 AND FOLATE DEFICIENCY
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ORs, respectively, 1.819 (95% CI, 1.372 – 2.411), 1.101
(95% CI, 0.931 – 1.301)] and macrocytosis [adjusted
ORs, respectively, 2.945 (95% CI, 1.747 – 4.965), 1.228
(95% CI, 0.795 – 1.898)]. Both low and marginal folate
status were related to male sex [age-adjusted ORs,
respectively, 2.026 (95% CI, 1.720 – 2.386), 1.804
(95% CI, 1.350 – 2.409)] (Table 3).
Age over 70 was significantly associated with low
vitamin B12 status [ORs, 1.338 (95% CI, 1.183 –
1.513) for 71 – 80 age group, 1.500 (95% CI, 1.221 –
1.843) for 81 – 85 age group] and low folate status
[ORs, 1.725 (95% CI, 1.187 – 2.507) for 71 – 80 age
group, 2.705 (95% CI, 1.606 – 4.556) for 81 – 85 age
group] (Table 4).
D IS C U S S IO N
In this study, we evaluated vitamin B12 and folate
levels in relation to anemia and macrocytosis which
are major hematologic manifestations of vitamin B12and folate deficiency. Our data showed that low b12
status was significantly associated with increased ane-
mia and macrocytosis, but marginal B12 status was
not associated with increased anemia and macrocyto-
sis. Although it is well known that vitamin b12 defi-
ciency causes pernicious anemia, observational
studies reported inconsistent results about vitamin
b12 deficiency and anemia relation [30 – 33]. More-
over, intervention studies investigating response to
vitamin b12 treatment reported conflicting results
[17 – 21, 23, 24]. Some of the studies did not demon-
strate a significant hemoglobin increase and MCV
decrease to vitamin b12 therapy. The data of previ-
ous intervention studies show that subjects who
responded to vitamin b12 treatment with an eleva-
tion of hemoglobin or decrease of MCV have lower
vitamin b12 levels than nonresponders [17, 19, 23].
This evidence is consistent with our finding. Mar-
ginal vitamin B12 status (151 – 200 pg/mL) has very
limited nonsignificant effect on anemia and macrocy-
tosis. This suggests that the appropriate vitamin B12
cutoff value to expect hematologic consequences as
anemia or macrocytosis is lower than the frequentlyused cutoff 200 pg/mL (148 pM). This also may
explain the inconsistency between intervention stud-
ies. Studies that included subjects with very low
Table 2. Anemia and macrocytosis in the three vitamin B12 groups
Vitamin B12 status
Normal
(n = 11 675)
Marginal
(n = 3439)
Low
(n = 2599)
(%) (%) OR (95% CI) P (%) OR (95% CI) P
Male 26.1 28 1.134 (1.041 – 1.237)* 0.004 32.1 1.300 (1.183 – 1.427)†
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vitamin b12 levels demonstrated significant response
to cobalamin therapy. Possibly subjects with subnor-
mal or marginal vitamin b12 levels did not showed
any hematologic response to therapy and caused
some studies to report nonsignificant results. Diag-
nosing vitamin B12 deficiency may be a complicated
issue in some patients. Anemia and macrocytosis are
often absent in cobalamin deficiency; in addition,
deficiency may be subtle or only with minor
neuropsychiatric symptoms [34–36]. MMA and hom-
ocystein are sensitive biomarkers and may be
increased in many patients with normal and subnor-
mal vitamin B12 concentrations. Using a higher cut-
off (>200 pg/mL) value for defining deficiency is
useful for diagnosing patients with neuropsychiatric
disorders or elevated MMA and homocystein concen-
trations, but we think that the cutoff value for he-
matologic disorders should be different and lower
from the value which is useful for diagnosing subtle
deficiency states. Anemia is a frequently encountered
problem in medical practice. The major causes of
anemia are iron deficiency and chronic inflammation
[37]. To determine whether anemia is caused by
cobalamin deficiency or not may be problematic. In
clinical practice, a subject with anemia and subnor-
mal vitamin B12 concentrations may be regarded as
vitamin b12 deficiency anemia although the underly-
ing cause was different in many cases. Using a
higher cutoff value may lead to an overdiagnosis of
vitamin B12 deficiency and an increase in the num-
ber of misdiagnosed anemic patients. We think that
laboratories should provide a hematologic cutoff
value to expect anemia and macrocytosis and a dif-
ferent higher cutoff value for subtle or neurologic
deficiency states. Cascade testing was proposed by
some authors [19, 26]. We agree with cascade testing
Table 3. Anemia and macrocytosis in the three folate groups
Folate status
Normal(n = 16 872)
Marginal
(n = 640)
Low
(n = 201)
(%) (%) OR (95% CI) P (%) OR (95% CI) P
Male 26.6 42 2.026 (1.720 – 2.386)*
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approach, but that approach did not define a distinct
hematologic cutoff value.
Low folate status but not marginal folate status was
significantly associated with anemia and macrocytoses.
In the present study, odds ratios of marginal folatestatus for anemia and macrocytosis were higher than
marginal vitamin b12 status. Intervention studies
about hematologic response to folate therapy in sub-
jects with subnormal folate concentrations are limited.
We think that there is not enough evidence to deter-
mine a hematologic cutoff for folate deficiency. The
usage of higher folate cutoff values may improve
sensitivity to detect deficiency.
We found that age over 70 was significantly associ-
ated with low vitamin B12 and folate status. Our
results are consistent with several studies which
reported that vitamin b12 deficiency and folate
deficiency were related with increasing age [1, 2, 38].
This retrospective study has some limitations.
Firstly, medical history of the subjects was not avail-
able; therefore, confounding factors may exist. Our
results reflect an outpatient population, and it is not
representative of general population. Biomarkers as
homocystein and MMA which can be used to distin-
guish between deficiency and nondeficiency states
were not available in our study. We were not able to
evaluate the association of these biomarkers with ane-mia and macrocytosis when used together with vita-
min B12 and folate. Lack of standardization between
B12 and folate assays is another limitation which
makes difficult to use a uniform reference value.
As a conclusion, current study that is based on a
large data set suggests that vitamin B12 relation with
anemia and macrocytosis should be reconsidered.
Determining a hematologic cutoff value may help
physicians in clinical practice.
A U T H O R C O N T R IB U T IO N SBT designed the study and wrote the paper. HZY
obtained data, drafted the paper, and provided critical
revisions. AC substantially contributed to analyses and
interpretation of the data.
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© 2013 John Wiley & Sons Ltd, Int. Jnl. Lab. Hem. 2014, 36, 409–414
414 B. TOPRAK, H. Z. YALCIN AND A. COLAK | VITAMIN B12 AND FOLATE DEFICIENCY