Abril - 2017

levels

individuals

heterozygous

for

hemoglobin

variants

ssoc

ras

2017; 63(4):341-346

343

Data were tabulated using statistical software, Mi-

crosoft Excel

and GraphPad Software, Inc., version

Prisma 6. Comparison of HbA1c levels between individu-

als heterozygous for hemoglobin variants and controls

with no change in hemoglobin structure was performed

based on standard deviation, mean and G-Test.

esults

We analyzed 50 patients heterozygous for hemoglobin

variants with normal blood glucose levels, of which 23

were male, representing 46% of the study population, and

27 were female, totaling 54%. Of the total 50, 16% are AC

and the remaining 84% are AS.

Dividing the group by age, we found 39 adults with

a mean age of 34.6 years (21 ± 38 years) and 11 children

and adolescents with a mean age of 5.9 years, ranging

from 1 to 13 years. In this group, no interferer was ob-

served, as described in Table 1.

TABLE 1

Assessment of interferers in a heterozygous

population.

Tests

Mean Minimum

value

Maximum

value

Reference

value

Urea

27 mg/dL 17 mg/dL 39 mg/dL 15-40 mg/dL

Triglycerides 113 mg/dL 80 mg/dL 143 mg/dL < 150 mg/dL

Total bilirubin 0.9 mg/dL 0.6 mg/dL 1.2 mg/dL ≤ 1.2 mg/dL

Source: Clinical Laboratory at PUC Goiás.

The mean values of HbA1c in heterozygous children were

at 5.11%, with a minimum of 3.9% and maximum of 5.97%.

The mean fasting glucose in this group was 89.56 mg/dL,

ranging from a minimum of 75 mg/dL to a maximum of

97 mg/dL, while mean hemoglobin was 12.9 g/dL, rang-

ing from 12.1 g/dL and 14 g/dL.

The mean A1c of heterozygous adults was close to the

values found for children, at 5.0%, ranging from a mini-

mum of 3.1% to a maximum of 6.9%. As for mean fasting

blood glucose, the adult population presented 84 mg/dL,

ranging from a minimum of 69 mg/dL to a maximum of

97 mg/dL. Mean hemoglobin was at 13.8 g/dL, ranging

from 12.3 g/dL to 15.8 g/dL.

In order to compare the data, we analyzed the same

tests in 50 patients without heterozygosity for hemoglo-

binopathies, with normal glycemic levels, of which 71.4%

were female. This group included 11 children and adoles-

cents, with a mean age of 10 years (6 ± 14 years). The fol-

lowing results were found in this class: HbA1c 5.78%, fast-

ing blood glucose 78.8 mg/dL and hemoglobin 14 g/dL.

With regard to the adult control population, 39 people

withmean age of 45 years (22 ± 37 years) were analyzed. We

found in this group the following mean test results: HbA1c

5.84%, ranging from 4.1% to a maximum of 6.9%, fasting

blood glucose at 89.3 mg/dL, ranging from 60 mg/dL to

99 mg/dL, and mean hemoglobin at 13.6 g/dL, ranging

from a minimum of 12 g/dL to a maximum of 15.7 g/dL.

HbA1c standard deviation of the children was then

calculated, reaching the result of 0.40 in the control group

and 0.75 in the test group. The standard deviation from

the adult test population was also calculated, which was

1.09 and the control was 0.57.

The value of the G-test was also determined, repre-

senting the result of HbA1c in the normal group compared

to the altered group, reaching p=0.93 for children and

p=0.89 for adults (Figures 1 and 2).

Of the 50 heterozygous individuals, ten had results

below the lower limit of 4%. Of these, eight were adults

and two were children, of whom nine were female. The

electrophoretic pattern of this group was verified and

eight fit the AS profile, while two were AC.

iscussion

This study showed significant similarity with the findings

of Menezes et al.,

whose comparative inferential analy-

sis of HbA1c was: AA, AS, AC and SS obtained from blood

samples from 150 participants, including diabetics, was

not significant, the same being observed in our study with

100 subjects who had normal glycemic levels.

Yedla, Kuchay and Mithal

evaluated the levels of

fasting blood glucose, postprandial blood glucose, fruc

tosamine and HbA1c (immunoassay technique) of a dia

betic patient, resulting in higher levels of fasting blood

glucose, postprandial blood glucose and fructosamine,

but not HbA1c, which remained normal. They concluded

that the result was underestimated, and a different tech

nique should be performed for this type of examination.

According to the study, ion exchange chromatography

(HPLC) as a method used to measure HbA1c is not influ-

enced by heterozygous hemoglobinopathies, as Copeland

et al.

report that some methodologies may have interfer-

ence from heterozygous hemoglobins.

In a study by Camargo and Gross,

the authors ana-

lyzed more than 25,000 samples and found patients het-

erozygous for HbS, HbC or HbD, noting that the presence

of a hemoglobin variant may yield lower (false) results.

However, anemia is also a source of negative interference.

The hematological status should be considered for the

correct interpretation of GHb results.

Despite cation exchange, HPLC is the reference meth

od, and the presence of hemoglobin variants may inter-

fere with levels of HbA1c, yielding false high or low levels