Number 54 n July 12, 2012

Biological Variation of Hematology Tests Based
 

on the 1999–2002 National Health and
 

Nutrition Examination Survey
 by David A. Lacher, M.D.; Janet Barletta, Ph.D.; and Jeffery P. Hughes, M.P.H.,

Division of Health and Nutrition Examination Surveys

Abstract

Objective—Biological variation consists of between-person (BP) and

within-person (WP) variation. Estimates of WP coefficients of variation (CVw)

and BP coefficients of variation (CVg) for hematology laboratory tests were

estimated from the 1999–2002 National Health and Nutrition Examination

Survey (NHANES).

Methods—NHANES is a survey of the civilian noninstitutionalized U.S.

population that uses a stratified, multistage probability design. Between- and

within-person variations were estimated for 18 hematology tests. For WP

variation, a nonrandom sample was obtained with a median of 17 days between

two test measurements. Between-person variation was estimated from the WP

sample and additional participants were matched for age group, gender, and race

and ethnicity to the WP sample.

Results—The BP and WP variations were estimated on as many as 2,496

and 852 sample participants, respectively. Mean corpuscular hemoglobin

concentration had the lowest CVg (2.25% for men and 2.40% for women), and

mean corpuscular volume had the lowest CVw (0.31% for men and 0.37% for

women). The index of individuality (CVw /CVg) ranged from 0.06 for mean

corpuscular volume for men and women to 0.62 for segmented neutrophil

number for men, and 0.55 for segmented neutrophil percent for women. Women

had higher CVw compared with men for hematocrit, hemoglobin, mean

corpuscular volume, red blood cell count, and red blood cell distribution width.

Several hematology tests’ CVw also differed by age group, including mean

corpuscular volume; eosinophil, lymphocyte and segmented neutrophil percent;

monocyte and segmented neutrophil number; white blood cell count; and red

blood cell distribution width.

Keywords: within-person variation • between-person variation • laboratory tests

Introduction

Laboratory analytes for individuals

are subject to several sources of

variation, including biological,

preanalytical (specimen collection),

analytical (bias and imprecision), and

postanalytical (reporting of results).

Analytical bias is the closeness of an

analyte result to the ‘‘true value’’ of the

result. Precision is the repeatability of

an analyte result if the same sample is

tested many times. Biological variation

consists of within-person (WP) and

between-person (BP) variation. These

components of biological variation are

used to set analytical goals for bias and

imprecision, evaluate changes for a

person’s tests using delta checks, and

assess the clinical utility of populationbased reference ranges (1).

The goals of imprecision and bias

for a laboratory analyte are different

depending on the intended use in

screening, diagnosis, or monitoring the

course of diseases in patients. When the

WP variation is much smaller than the

BP variation, the individual results stay

within a narrow range compared with

the population-based reference interval

(range). Hence, the WP variation would

be used to monitor serial changes of

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Center for Health Statistics 
Page 2 National Health Statistics Reports n Number 54 n July 12, 2012

laboratory values in a person. Contrarily,

when the WP variation is similar to the

BP variation, the person’s results over

time have a wide range comparable with

the population-based reference interval.

In this situation, the BP variation

(population reference range) is used to

monitor serial change of the laboratory

values in a person. Ideally, desirable

goals for imprecision (I) and bias (B)

have been related to the WP coefficients

of variation (CVw) and the BP

coefficients of variation (CVg) of

laboratory analytes (1–3).

Buttarello discussed sources of

variation of hematology analytes (4).

Preanalytical sources of variation

include type of anticoagulant used,

specimen storage temperatures, and

stability. Postanalytical sources of

variation include delta checks

(differences between consecutive

laboratory values of a test), limit checks

(laboratory values when exceeded

requiring further investigation), and

reports of unusual cell morphology.

Analytical variation sources of

imprecision and bias of hematology tests

have been characterized by monitoring

quality controls, proficiency testing, and

comparing automated instrument

measurements with manual methods.

BP variation of hematology tests

has been studied extensively for

demographic characteristics including

age and gender. The WP source of

biological variation has been evaluated

for chemistry tests, but rarely for

hematology tests. Most hematology

studies of biological variation had few

subjects. Statland examined the mean

hourly, daily, and weekly intraindividual variation of hematology tests

in 20 adults (5). Costongs examined

daily, weekly, and 6-month intraindividual variations of hematology tests

for 62 adults aged 18–57 (6). Costongs

also examined the critical differences

(delta checks) using WP data. Costongs

noted that the WP coefficients of

variation were indirectly related to the

life span of cells, with red blood cells

(life span 120 days) having the lowest

CVw and white blood cells (life span

6–8 hours) having the highest CVw.

Fraser examined WP and BP variation

of hematology tests in 24 elderly

persons (mean age 75) over 20 weeks at

14-day intervals (7). Ricos (2) and

Fraser (1) have compiled lists of WP

and BP variation for laboratory tests,

including hematology tests.

The WP and BP variation of

laboratory tests has been examined in

several NHANES surveys. Looker

examined hematology and biochemical

markers of iron status in the Hispanic

Health and Nutrition Examination

Survey conducted from 1982 through

1984 for 80 persons (8). The effect of

increased WP variation on

overestimation of prevalence of

hematologic disorders was examined.

WP and BP variation have been reported

for selected analytes from the third

National Health and Nutrition

Examination Survey conducted from

1988 through 1994 (9). The BP and WP

variation for general biochemical,

nutritional, and environmental analytes

was analyzed for the 1999–2002

National Health and Nutrition

Examination Survey (10). In this report,

BP and WP variations of hematology

tests are presented for NHANES

1999–2002, and gender and age groups

are compared for WP variation.

Methods and

Procedures

Estimates of CVw and CVg for

laboratory tests were calculated from the

1999–2002 NHANES (11,12), a

cross-sectional survey that collected data

on the civilian noninstitutionalized U.S.

population through questionnaires and

medical examinations, including

laboratory tests. NHANES 1999–2002

used a stratified, multistage probability

design to collect a nationally

representative sample.

The hematology tests were collected

in EDTA tubes as part of a complete

blood and five-part differential cell

count profile and were analyzed on the

Beckman Coulter MAXM analyzer

(Beckman Coulter Corporation, Brea,

Calif.). Details of the laboratory

methods have been described (13) and

the 18 hematology tests are listed in

Tables 1–5.

The MAXM instrument is a

laser-based flow cytometer that uses

impedance, conductivity, and light

scatter to directly measure some of the

hematology tests. Other hematology

tests are calculated from the directly

measured analytes. The method

analytical CV (CVa ) used to calculate

the CVw was derived from imprecision

CV using bench quality controls or

imprecision based on manufacturer

information.

The BP and WP means, standard

deviations, and coefficients of variation

for hematology tests are shown for men

in Table 1 and for women in Table 2.

The BP sample was generated from the

WP sample, and two additional

participants were selected for every one

WP sample participant. The additional

BP participants were selected by

matching for gender, race and ethnicity,

and age group. BP participants were

matched in 3-year age groups (e.g.,

16–18, 19–21, 22–24, 25–27, etc.) to

have more participants to compare with

3-year age groups in the WP sample.

The BP variations were estimated on as

many as 2,496 sample participants from

NHANES 1999–2002. The WP

variations were estimated from a

convenience sample of 852 persons

based on NHANES 2000–2002 data.

The WP sample participants were

recruited for a second test measurement.

The WP participants were not selected

randomly but recruited according to

several criteria, including selecting

approximately equal proportions of men

and women with an approximately

uniform age distribution of 16–69 years.

Participants were recruited to obtain

about equal numbers for race and

ethnicity of Mexican-American,

non-Hispanic black, non-Hispanic white,

and other persons. The target size of the

WP sample was 5% of those participants

who had a venipuncture during the

initial visit to the NHANES mobile

examination center. The WP participants

were asked to return for a second

phlebotomy no sooner than 8 days after

their initial blood draw (1.8% of

participants had second phlebotomies

before 8 days). Because the BP sample

was matched for age and gender to the

WP sample, no differences in

proportions by gender were seen for the

age groups (16–29, 30–49, and 50–69).
National Health Statistics Reports n Number 54 n July 12, 2012 Page 3

A chi-square test showed no significant

differences between age groups by

gender for the WP ( p = 0.71) and BP

( p = 0.44) sample.

The WP variation was estimated

from a nonrandom, unweighted sample

with a median of 17 days (25th

percentile: 13 days, 75th percentile: 23

days, range: 3–51 days) between two

test measurements. The analytical

variation includes the imprecision and

changes in bias (for example, changes in

method calibration) that are usually

negligible. Hence, the CVa is estimated

by the method imprecision CV (CVi

).

The total coefficient of variation (CVt

)

of a laboratory analyte can be estimated

assuming that all sources of error are

measured at the same analyte mean and

that preanalytical and postanalytical

sources of variation are negligible. The

)

2

]

1/2 CVt is calculated as [(CVa)2 + (CVw

(1). Hence, the CV was calculated as

[(CVt)

2 – (CVa)2

]

1/2w

. The CVg was

calculated as SD/mean for the BP

sample. The distributions of several

hematology tests were nongaussian, and

extreme outliers were excluded to obtain

an approximately gaussian distribution

with more stable estimates of variation.

Outliers were eliminated by use of

Tukey’s method, which defines outliers

as three interquartile ranges below the

25th percentile or above the 75th

percentile (14). The basophil and

eosinophil number had extreme

nongaussian distributions and were

excluded. Gender and age group WP

variations were compared. Ninety-five

percent confidence intervals were

estimated for the CVw. A likelihood

ratio test was performed to determine if

the CVw for gender or age group for a

laboratory analyte were equal (15).

Statistical analyses were carried out with

SAS for Windows software (SAS

Institute, Cary, N.C.).

Results and Discussion

The BP and WP means, standard

deviations, and coefficients of variation

for 18 hematology tests are shown for

men in Table 1 and for women in

Table 2. The mean of hematology tests

of the BP and WP sample for men and

for women, respectively, were similar.

As expected, the BP mean red blood

cell-related hematology tests

(hemoglobin, hematocrit, and red blood

cell count) were higher for men

compared with women. The CVg

exceeded the laboratory CVi for all

hematology tests. The CVw exceeded

the laboratory CVi for 15 of 18

hematology tests. However, the CVw

was less than the laboratory CVi for

basophil percent, mean corpuscular

hemoglobin, and mean corpuscular

hemoglobin concentration. The CVw

cannot be estimated for these

hematology tests because the CVw is

calculated as [(CVt

2

) – (CVa)

2

]

1/2 and

CVa, as estimated by CVi

, exceeded the

CVt

. The imprecision of the hematology

tests were estimated from between-run

bench quality controls that are used

most commonly to estimate imprecision

of tests for biological variation. Because

the WP CV is estimated over several

runs, the between-run imprecision was

used.

Analytical goals for imprecision and

bias can be judged using the CVw and

CVg. Imprecision should ideally be less

than one-half of the CVw, and bias

should be less than 0.25 [(CVw)

2 +

(CVg)

2

]

1/2 (1). The total error of a

laboratory measurement reflects the

underlying bias and imprecision of an

analyte. The goal for total error should

be less than kI + B, where k = 1.65 for

α = 0.05 (1). For example, the observed

hemoglobin imprecision of 1.1% was

less than the imprecision goal of

one-half of CVw (2.46%), or 1.23% in

men (Table 1). The bias for hemoglobin

in men should ideally be less than

)

2

]

1/2 0.25[(CVw)2 + (CVg , or

0.25[(0.0246)2 + (0.0785)2

]

1/2, or 8.2%.

The total error is estimated as B +

1.65(I), or 8.2% + 1.65(1.1%), or

10.0%. Thus, the total error for

hemoglobin in men estimated at the BP

mean of 15.3 g/dL (Table 1) was 1.53

g/dL (15.3 g/dL multiplied by 0.10). The

total error of 10.0% for male

hemoglobin exceeded the Clinical

Laboratory Improvement Amendments

acceptable performance for total error

for hemoglobin of 7% (16).

The mean corpuscular hemoglobin

concentration (MCHC) CVg of 2.25%

was lowest among all the hematology

tests in men (Table 1) and 2.40% for

women (Table 2). Compared with all

other hematology tests, the MCHC

between-person CV was lowest in all

age groups, with 2.33% for participants

aged 16–29 (Table 3), 2.39% for

participants aged 30–49 (Table 4), and

2.29% for participants aged 50–69

(Table 5). The mean corpuscular volume

(MCV) CVw was lowest among

hematology tests in men (0.31%) and

women (0.37%). The MCV withinperson CV was also lowest among

hematology tests in all age groups with

0.28% for ages 16–29, 0.51% for ages

30–49, and 0.18% for ages 50–69. The

low within-person CV for MCHC can

be seen for men and women (Figure 1).

High CVg was seen in eosinophil

and basophil percent for men and

women (range 52.4%–64.4%) and in all

age groups (range 50.8%–68.6%), which

reflects very low analyte values. Other

hematology analytes also had relatively

high CVg (greater than 25%) including

white blood count, segmented

neutrophil, lymphocyte and monocyte

number, and lymphocyte and monocyte

percent. High CVw was seen in

eosinophil percent and segmented

neutrophil number in men and women

(range: 21.5%–25.2%) and in all groups

(range: 19.1%–26.5%). High withinperson CV reflects individual variation

due to gender, age, diurnal or cyclical

variation, disease, or very low analyte

values. The high within-person CV for

segmented neutrophil number can be

seen for men and women in Figure 2.

The ratio of CVw to CVg, also

known as the index of individuality, is

important in determining the use of

population-based reference (normal)

intervals in detecting changes of disease

status in individuals (17,18). When the

index of individuality is low (< 0.5), the

individual results stay within a narrow

range compared with the populationbased reference interval. Hence, a low

index suggests the utility of evaluating

serial changes in analyte values in an

individual, whereas population-based

reference intervals would be of limited

use. A high index (≥ 0.5) suggests that

the population-based reference interval

is appropriate when interpreting a

person’s laboratory analyte value. The
Page 4 National Health Statistics Reports n Number 54 n July 12, 2012

0 70 75 80 85 90 95 100 105 110 

0 

70 

80 

90 

100 

110 

0 70 75 80 85 90 95 100 105 110 

0 

70 

80 

90 

100 

110 

NOTE: fL is femtoliter. 

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey, 1999–2002. 

First-day mean cell volume (fL) 

Women 

Men 

Second-day mean cell volume (fL) 

Figure 1. First-day versus second-day cell volume, by gender

index of individuality ranged from 0.06

for mean corpuscular volume for men

and women, to 0.62 for segmented

neutrophil number for men and 0.55 for

segmented neutrophil percent for women

(Tables 1 and 2). The index of

individuality was lowest for mean

corpuscular volume for all age groups

(0.05 for ages 16–29, 0.09 for ages

30–39, and 0.03 for ages 50–69)

(Tables 3–5). The index of individuality

was highest for segmented neutrophil

percent (0.63) for ages 16–29. For ages

30–49, segmented neutrophil and

lymphocyte percent had the highest

index of individuality (0.52); and for

ages 50–69, segmented neutrophil

number and percent had the highest

index of individuality (0.53).

The BP and WP variations were

analyzed by gender. The sample size,

means, standard deviations, and

coefficients of variation for hematology

analytes are presented for men (Table 1)

and women (Table 2). Several laboratory

analytes had significant differences (p

< 0.001) in the CVw when males and

females were compared. Women had

higher CVw compared with men for

tests associated with red blood cells

including, hematocrit, hemoglobin, mean

corpuscular volume, red blood cell

count, and red blood cell distribution

width. For example, the red blood cell

count CVw in women was 3.45%

compared with 2.53% in men. Females

may have more within-person variation

due to blood loss during menstruation or

increased iron utilization during

pregnancy.

The BP and WP variations of

hematology analytes were also analyzed

by age group. The sample size, means,

standard deviations, and coefficients of

variation of hematology analytes are

presented for age groups 16–29

(Table 3), 30–49 (Table 4), and 50–69

(Table 5). Several hematology tests also

differed (p < 0.05) by age group while

controlling for gender. Participants aged

16–29 had higher CVw than those aged

30–49 and 50–69 for eosinophil,

lymphocyte, and segmented neutrophil

percent, and segmented neutrophil

number. Also, participants aged 16–29

had higher CVw than those aged 50–69

for monocyte number, red blood cell

distribution width, and white blood

count. Participants aged 30–49 had

higher CVw than those aged 50–69 for

monocyte number, red blood cell

distribution width, and white blood

count. Mean corpuscular volume CVw

was highest in the middle age group,

with 0.28% for those aged 16–29,

0.51% for those aged 30–49, and 0.18%

for those aged 50–69 (Figure 3).

In this report, BP and WP estimates

of coefficients of variation were

obtained for 18 hematology analytes.

The literature on WP hematology

variation is very limited, and this report

adds information on within-person

coefficients of variation. NHANES

1999–2002 provides a better estimate of

BP variation than other locally

representative studies because the

NHANES sample was nationally

representative and had a larger sample

size. The WP variation estimate was

limited by the nonrandom, self-selected

design and reflected a median of 17

days between two measurements. In

addition, the CVw and CVg estimates in

NHANES were based on a relatively

healthy sample of the population. The

CVw and CVg would be increased in a

sample of unhealthy individuals because

of changes in disease status and

treatment. The BP and WP sample
National Health Statistics Reports n Number 54 n July 12, 2012 Page 5

0 2 4 6 8 10 12 

0 

2 

4 

6 

8 

10 

12 

0 2 4 6 8 10 12 

0 

2 

4 

6 

8 

10 

12 

NOTE: μL is microliter. 

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey, 1999–2002. 

First-day segmented neutrophil number (1,000 cells/μL) 

Second-day segmented neutrophil number (1,000 cells/μL)

Women 

Men 

Figure 2. First-day versus second-day segmented neutrophil number, by gender

participants were restricted to those aged

16–69. The estimate of CVw could be

improved by use of a stratified,

multistage probability design over

different time periods.
Page 6	 National Health Statistics Reports n Number 54 n July 12, 2012

0 70 75 80 85 90 95 100 105 110 

0 

70 

80 

90 

100 

110 

0 70 75 80 85 90 95 100 105 110 

0 

70 

80 

90 

100 

110 

NOTE: fL is femtoliter. 

SOURCE: CDC/NCHS, National Health and Nutrition Examination Survey, 1999–2002. 

First-day mean cell volume (fL) 

0 70 75 80 85 90 95 100 105 110 

0 

70 

80 

90 

100 

110 

Second-day mean cell volume (fL) 

16–29 years 

30–49 years 

50–69 years 

Figure 3. First-day versus second-day mean cell volume, by age group

References

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From principles to practice.

Washington, DC: AACC Press;

p 151. 2001.

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et al. Current databases on biological

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4.Buttarello M. Quality specification in

hematology: the automated blood cell

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Burdsall MJ, Saunders AM.

Evaluation of biologic sources of

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6.Costongs GM, Janson PC, Bas BM,

Hermans J, Van Wersch JW,

Brombacher, PJ. Short-term and

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RG, Knox JD, King JF, MacWalter

RS. Biologic variation of common

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the elderly. Am J Clin Pathol

92:465–70. 1989.

8.Looker AC, Sempos CT, Liu K,

Johnson CL, Gunter EW. Withinperson variance in biochemical

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Biological variation of laboratory

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National Health and Nutrition

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MD: National Center for Health

Statistics. 2010.
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11. National Center for Health Statistics.

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www.cdc.gov/nchs/nhanes/

nhanes1999-2000/nhanes99_00.htm.

Accessed December 28, 2011.

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NHANES 2001–2002 public data

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nhanes2001-2002/nhanes01_02.htm.

Accessed December 28, 2011.

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Page 8 National Health Statistics Reports n Number 54 n July 12, 2012

Table 1. Between-person (CVg), within-person (CVw), and method (CVa) coefficients of variation for men

Between-person Within-person Method1 Index2

CVg CVw CVa

Analyte (units) n Mean SD (percent) n Mean SD (percent) (percent) CVw /CVg

Basophil percent (percent) ................. 1,202 0.6136 0.3401 55.43 404 0.6113 0.2520 † 43.6 †
 

Eosinophil percent (percent) ................ 1,187 2.8726 1.7027 59.27 401 2.8434 0.7251 23.19 10.6 0.39
 

Hematocrit (percent) ..................... 1,209 45.2174 3.4936 7.73 411 44.8138 1.3504 ††2.49 1.7 0.32
 

Hemoglobin (g/dL) ...................... 1,209 15.2793 1.1993 7.85 411 15.1369 0.4083 ††2.46 1.1 0.31
 

Lymphocyte number (103

/μL) ............... 1,203 2.0331 0.6239 30.69 409 2.0359 0.3190 15.25 3.6 0.50
 

Lymphocyte percent (percent) ............... 1,208 30.2634 8.2636 27.31 411 30.4782 4.6946 15.13 2.9 0.55
 

Mean corpuscular hemoglobin (pg) ............ 1,205 30.3496 1.9173 6.32 411 30.2988 0.3293 † 1.9 †
 

Mean corpuscular volume (fL) ............... 1,205 89.7963 4.9216 5.48 411 89.6760 0.6870 †0.31 0.7 0.06
 

Mean corpuscular hemoglobin concentration (g/dL) . . 1,207 33.7803 0.7595 2.25 411 33.7725 0.4470 † 2.0 †
 

Mean platelet volume (fL).................. 1,208 8.3079 0.8620 10.38 411 8.2764 0.3052 3.32 1.6 0.32
 

Monocyte number (103

/μL) ................. 1,208 0.5810 0.1798 30.95 410 0.5719 0.1025 16.96 5.8 0.55
 

Monocyte percent (percent) ................ 1,204 8.5485 2.1076 24.65 409 8.4719 1.2026 13.13 5.4 0.53
 

Platelet count (103

/μL). . . . . . . . . . . . . . . . . . . . 1,209 255.7469 59.0561 23.09 411 254.8273 22.4919 8.26 3.1 0.36
 

Red blood cell count (106

/μL) ............... 1,209 5.0512 0.4461 8.83 411 5.0107 0.1475 ††2.53 1.5 0.29
 

Red blood cell distribution width (percent)........ 1,200 12.5278 0.7365 5.88 404 12.5238 0.1844 ††0.85 1.2 0.14
 

Segmented neutrophil number (103

/μL) ......... 1,206 4.0595 1.5038 37.04 409 4.0158 0.9241 22.86 2.6 0.62
 

Segmented neutrophil percent (percent) ......... 1,208 57.5146 9.3889 16.32 411 57.3492 5.6188 9.67 1.6 0.59
 

White blood cell count (103

/μL) .............. 1,206 6.9368 1.9161 27.62 409 6.8861 1.0490 15.09 2.1 0.55
 

† CVw could not be calculated because the CVt (total coefficient of variation) was less than the CVa. †† p < 0.001 where the CVw for men is equivalent to the CVw for women.
 1

Method analytical CV is the laboratory method precision assuming no method bias exists.
 2

Index of individuality.
 

NOTE: CV is coefficient of variation, n is the size of the sample, and SD is standard deviation; g/dL is grams per deciliter, μL is microliter, pg is picogram, and fL is femtoliter.
 

Table 2. Between-person (CVg), within-person (CVw), and method (CVa) coefficients of variation for women

Between-person Within-person Method1 Index2

CVg CVw CVa

Analyte (units) n Mean SD (percent) n Mean SD (percent) (percent) CVw /CVg

Basophil percent (percent) ................. 1,264 0.6275 0.3290 52.43 432 0.6089 0.2472 † 43.6 †
 

Eosinophil percent (percent) ................ 1,263 2.2864 1.4722 64.39 431 2.3305 0.6363 25.16 10.6 0.39
 

Hematocrit (percent) ..................... 1,287 39.2953 3.5273 8.98 441 38.8971 1.4150 ††3.22 1.7 0.36
 

Hemoglobin (g/dL) ...................... 1,286 13.3306 1.2251 9.19 441 13.1939 0.4408 ††3.15 1.1 0.34
 

Lymphocyte number (103

/μL) ............... 1,271 2.1952 0.6571 29.93 435 2.1785 0.3405 15.21 3.6 0.51
 

Lymphocyte percent (percent) ............... 1,275 30.4178 8.7653 28.82 438 30.6664 4.7715 15.29 2.9 0.53
 

Mean corpuscular hemoglobin (pg) ............ 1,276 30.3926 2.0561 6.77 438 30.4028 0.3874 † 1.9 †
 

Mean corpuscular volume (fL) ............... 1,276 89.5221 5.1025 5.70 438 89.5771 0.7072 †0.37 0.7 0.06
 

Mean corpuscular hemoglobin concentration (g/dL) . . 1,285 33.9005 0.8126 2.40 440 33.9013 0.4600 † 2.0 †
 

Mean platelet volume (fL).................. 1,286 8.3452 0.8685 10.41 440 8.3045 0.2850 3.04 1.6 0.29
 

Monocyte number (103

/μL) ................. 1,274 0.5448 0.1811 33.24 434 0.5355 0.0956 16.88 5.8 0.51
 

Monocyte percent (percent) ................ 1,271 7.4059 1.9803 26.74 434 7.4089 1.1047 13.90 5.4 0.52
 

Platelet count (103

/μL). . . . . . . . . . . . . . . . . . . . 1,284 284.1636 65.7434 23.14 440 286.2356 25.8905 8.50 3.1 0.37
 

Red blood cell count (106

/μL) ............... 1,287 4.4085 0.4112 9.33 441 4.3609 0.1639 ††3.45 1.5 0.37
 

Red blood cell distribution width (percent)........ 1,255 12.6133 0.8957 7.10 426 12.6033 0.2088 ††1.14 1.2 0.16
 

Segmented neutrophil number (103

/μL) ......... 1,269 4.5634 1.8853 41.31 434 4.4961 0.9756 21.54 2.6 0.52
 

Segmented neutrophil percent (percent) ......... 1,275 59.1355 9.8992 16.74 438 58.8229 5.4819 9.18 1.6 0.55
 

White blood cell count (103

/μL) .............. 1,284 7.5669 2.2940 30.32 439 7.4773 1.1411 15.12 2.1 0.50
 

†CVw could not be calculated because the CVt (total coefficient of variation) was less than the CVa. †† p < 0.001 where the CVw for women is equivalent to the CVw for men.
 1

Method analytical CV is the laboratory method precision assuming no method bias exists.
 2

Index of individuality.
 

NOTE: CV is coefficient of variation, n is the size of the sample, and SD is standard deviation; g/dL is grams per deciliter, μL is microliter, pg is picogram, and fL is femtoliter.
 
National Health Statistics Reports n Number 54 n July 12, 2012 Page 9

Table 3. Between-person (CVg), within-person (CVw), and method (CVa) coefficients of variation for ages 16–29

Between-person Within-person Method1 Index2

CVg CVw CVa

Analyte (units) n Mean SD (percent) n Mean SD (percent) (percent) CVw /CVg

Basophil percent (percent) ................. 933 0.5855 0.3250 55.51 316 0.5720 0.2522 6.56 43.6 0.12
 

Eosinophil percent (percent) ................ 927 2.4787 1.7016 68.65 314 2.5250 0.7212 ††§26.52 10.6 0.39
 

Hematocrit (percent) ..................... 948 42.1853 4.9338 11.70 323 41.7453 1.4448 3.01 1.7 0.26
 

Hemoglobin (g/dL) ...................... 948 14.2814 1.6471 11.53 323 14.1255 0.4472 2.97 1.1 0.26
 

Lymphocyte number (103

/μL) ............... 942 2.1193 0.5775 27.25 322 2.1269 0.3607 16.57 3.6 0.61
 

Lymphocyte percent (percent) ............... 942 29.7635 8.4699 28.46 323 30.3860 5.3899 ††§17.50 2.9 0.61
 

Mean corpuscular hemoglobin (pg) ............ 944 29.9992 1.8863 6.29 322 29.9315 0.3430 † 1.9 †
 

Mean corpuscular volume (fL) ............... 944 88.5487 4.7171 5.33 322 88.3978 0.6674 ††§0.28 0.7 0.05
 

Mean corpuscular hemoglobin concentration (g/dL) . . 947 33.8528 0.7871 2.33 323 33.8376 0.4536 † 2.0 †
 

Mean platelet volume (fL).................. 948 8.3373 0.8468 10.16 323 8.3117 0.2755 2.90 1.6 0.29
 

Monocyte number (103

/μL) ................. 942 0.5715 0.1805 31.58 319 0.5596 0.1084 §18.48 5.8 0.59
 

Monocyte percent (percent) ................ 938 7.8592 2.1430 27.27 321 7.8378 1.2305 14.74 5.4 0.54
 

Platelet count (103

/μL). . . . . . . . . . . . . . . . . . . . 947 274.7899 62.2138 22.64 322 275.0288 23.6701 8.03 3.1 0.35
 

Red blood cell count (106

/μL) ............... 948 4.7779 0.5685 11.90 323 4.7345 0.1666 3.18 1.5 0.27
 

Red blood cell distribution width (percent)........ 938 12.4317 0.7725 6.21 317 12.4518 0.2088 ††§1.17 1.2 0.19
 

Segmented neutrophil number (103

/μL) ......... 937 4.5216 1.8752 41.47 320 4.4185 1.1077 ††§24.93 2.6 0.60
 

Segmented neutrophil percent (percent) ......... 942 59.1222 10.0118 16.93 323 58.4152 6.2716 ††§10.62 1.6 0.63
 

White blood cell count (103

/μL) .............. 945 7.4681 2.1937 29.37 321 7.3608 1.2311 §16.59 2.1 0.56
 

† CVw could not be calculated beause the CVt (total coefficient of variation) was less than the CVa. †† p < 0.05 where the CVw for ages 16–29 is equivalent to the CVw for ages 30–49. § p < 0.05 where the CVw for ages 16–29 is equivalent to the CVw for ages 50–69. 1

Method analytical CV is the laboratory method precision assuming no method bias exists. 2

Index of individuality.

NOTE: CV is coefficient of variation, n is the size of the sample, and SD is standard deviation; g/dL is grams per deciliter, μL is microliter, pg is picogram, and fL is femtoliter.

Table 4. Between-person (CVg), within-person (CVw), and method (CVa) coefficients of variation for ages 30–49

Between-person Within-person Method1 Index2

CVg CVw CVa

Analyte (units) n Mean SD (percent) n Mean SD (percent) (percent) CVw /CVg

Basophil percent (percent) ................. 711 0.6338 0.3478 54.88 247 0.6059 0.2592 † 43.6 †
 

Eosinophil percent (percent) ................ 704 2.5851 1.5915 61.56 243 2.5565 0.6195 ††21.79 10.6 0.35
 

Hematocrit (percent) ..................... 717 42.1471 4.7161 11.19 250 41.7556 1.3438 2.73 1.7 0.24
 

Hemoglobin (g/dL) ...................... 716 14.2804 1.6163 11.32 250 14.1346 0.4259 2.81 1.1 0.25
 

Lymphocyte number (103

/μL) ............... 711 2.1187 0.6526 30.80 246 2.0975 0.3122 14.44 3.6 0.47
 

Lymphocyte percent (percent) ............... 713 30.0931 8.2474 27.41 247 29.8556 4.3174 ††14.17 2.9 0.52
 

Mean corpuscular hemoglobin (pg) ............ 708 30.4545 2.0584 6.76 248 30.4521 0.3662 † 1.9 †
 

Mean corpuscular volume (fL) ............... 709 89.8405 5.2307 5.82 248 89.9136 0.7764 ††§0.51 0.7 0.09
 

Mean corpuscular hemoglobin concentration (g/dL) . . 714 33.8506 0.8092 2.39 250 33.8259 0.4622 † 2.0 †
 

Mean platelet volume (fL).................. 717 8.3230 0.8853 10.64 250 8.3039 0.3061 3.32 1.6 0.31
 

Monocyte number (103

/μL) ................. 712 0.5534 0.1829 33.05 247 0.5466 0.0982 §17.00 5.8 0.51
 

Monocyte percent (percent) ................ 712 7.8206 2.1465 27.45 247 7.7437 1.0870 12.96 5.4 0.47
 

Platelet count (103

/μL). . . . . . . . . . . . . . . . . . . . 716 270.3324 63.9326 23.65 250 274.1162 27.0170 9.36 3.1 0.40
 

Red blood cell count (106

/μL) ............... 717 4.7159 0.5541 11.75 250 4.6680 0.1499 2.84 1.5 0.24
 

Red blood cell distribution width (percent)........ 702 12.5634 0.8169 6.50 244 12.5686 0.2073 §

1.13 1.2 0.17
 

Segmented neutrophil number (103

/μL) ......... 710 4.3717 1.7671 40.42 245 4.3998 0.9214 ††20.78 2.6 0.51
 

Segmented neutrophil percent (percent) ......... 713 58.7757 9.3722 15.95 247 59.1327 4.9860 ††8.28 1.6 0.52
 

White blood cell count (103

/μL) .............. 716 7.3325 2.2344 30.47 249 7.3099 1.1019 §14.93 2.1 0.49
 

†CVw could not be calculated because the CVt (total coefficient of variation) was less than the CVa.

†† p < 0.05 where the CVw for ages 30–49 is equivalent to the CVw for ages 16–29. § p < 0.05 where the CVw for ages 30–49 is equivalent to the CVw for ages 50–69. 1

Method analytical CV is the laboratory method precision assuming no method bias exists. 2

Index of individuality.

NOTE: CV is coefficient of variation, n is the size of the sample, and SD is standard deviation; g/dL is grams per deciliter, μL is microliter, pg is picogram, and fL is femtoliter.
Page 10 National Health Statistics Reports n Number 54 n July 12, 2012

Table 5. Between-person (CVg), within-person (CVw), and method (CVa) coefficients of variation for ages 50–69

Between-person Within-person Method1 Index2

CVg CVw CVa

Analyte (units) n Mean SD (percent) n Mean SD (percent) (percent) CVw /CVg

Basophil percent (percent) ................. 822 0.6494 0.3301 50.83 273 0.6579 0.2372 † 43.6 †

Eosinophil percent (percent) ................ 819 2.6615 1.5270 57.37 275 2.6576 0.6841 ††23.46 10.6 0.41

Hematocrit (percent) ..................... 831 42.1535 4.0522 9.61 279 41.7727 1.3478 2.74 1.7 0.29

Hemoglobin (g/dL) ...................... 831 14.2627 1.3862 9.72 279 14.1416 0.3983 2.59 1.1 0.27

Lymphocyte number (103

/μL) ............... 821 2.1110 0.7125 33.75 276 2.0993 0.3079 14.22 3.6 0.42

Lymphocyte percent (percent) ............... 828 31.2165 8.7549 28.05 279 31.4283 4.2513 ††13.21 2.9 0.47

Mean corpuscular hemoglobin (pg) ............ 829 30.7252 1.9741 6.43 279 30.7499 0.3747 † 1.9 †

Mean corpuscular volume (fL) ............... 828 90.7583 4.9009 5.40 279 90.7854 0.6562 ††§0.18 0.7 0.03

Mean corpuscular hemoglobin concentration (g/dL) . . 831 33.8232 0.7756 2.29 278 33.8528 0.4462 † 2.0 †

Mean platelet volume (fL).................. 829 8.3191 0.8699 10.46 278 8.2550 0.3063 3.35 1.6 0.32

Monocyte number (103

/μL) ................. 828 0.5598 0.1808 32.30 278 0.5515 0.0880 ††§14.87 5.8 0.46

Monocyte percent (percent) ................ 825 8.2001 2.0554 25.07 275 8.1850 1.1173 12.54 5.4 0.50

Platelet count (103

/μL). . . . . . . . . . . . . . . . . . . . 830 265.3976 66.2470 24.96 279 263.7113 22.3984 7.91 3.1 0.32

Red blood cell count (106

/μL) ............... 831 4.6569 0.4696 10.08 279 4.6127 0.1492 2.87 1.5 0.28

Red blood cell distribution width (percent)........ 815 12.7395 0.8533 6.70 269 12.6921 0.1725 ††§0.64 1.2 0.10

Segmented neutrophil number (103

/μL) ......... 828 4.0412 1.4670 36.30 278 3.9632 0.7627 ††19.07 2.6 0.53

Segmented neutrophil percent (percent) ......... 828 57.0955 9.4604 16.57 279 56.8519 5.1126 ††8.85 1.6 0.53

White blood cell count (103

/μL) .............. 829 6.9653 1.9639 28.20 278 6.8919 0.9152 ††§13.11 2.1 0.46

† CVw could not be calculated because the CVt (total coefficient of variation) was less than the CVa. †† p < 0.05 where the CVw for ages 50–69 is equivalent to the CVw for ages 16–29. § p < 0.05 where the CVw for ages 50–69 is equivalent to the CVw for ages 30–49. 1

Method analytical CV is the laboratory method precision assuming no method bias exists. 2

Index of individuality.

NOTE: CV is coefficient of variation, n is the size of the sample, and SD is standard deviation; g/dL is grams per deciliter, μL is microliter, pg is picogram, and fL is femtoliter.
National Health Statistics Reports n Number 54 n July 12, 2012 Page 11
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National Health Statistics Reports n Number 54 n July 12, 2012

Suggested citation

Lacher DA, Barletta J, Hughes JP. Biological

variation of hematology tests based on the

1999–2002 National Health and Nutrition

Examination Survey. National health statistics

reports; no 54. Hyattsville, MD: National

Center for Health Statistics. 2012.

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Division of Health and Nutrition
 

Examination Surveys
 

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