T H E AMEBICAN JOURNAL OF CLINICAL PATHOLOGY
Vol. 36, No. 3, pp. 212-219
September, 1961
Copyright © 1961 by The Williams & Wilkins Co.
Printed in U.S.A.
T H E PARTIAL THROMBOPLASTIN T I M E WITH KAOLIN
A SIMPLE SCREENING TEST FOR FIRST STAGE PLASMA CLOTTING FACTOR
DEFICIENCIES
R O B E R T R. P R O C T O R , M . D . , AND SAMUEL I. R A P A P O R T , M . D .
University
of Southern California
Medical School, Los Angeles,
The partial thromboplastin time (PPT)
test2 consists of recalcifying plasma in the
presence of a lipid reagent that supplies
optimal platelet thromboplastic factor-like
activity. Thus, the test measures the overall adequacy of the intrinsic plasma-clotting
factors. It has proven particularly valuable6,10 in the recognition of hemophilia and
the hemophilioid states, i.e., deficiencies of
antihemophilic globulin (AHG, Factor VIII),
of plasma thromboplastin component (PTC,
Factor IX), of plasma thromboplastin antecedent (PTA), and of Hageman factor (HF).
Despite its simplicity, the P T T is not
widely used in clinical laboratories. Instead, when faced with the task of screening
patients for possible plasma thromboplastic
factor deficiencies, most laboratories either
rely upon insensitive or erratic technics,
such as clotting times or prothrombin consumption tests, or resort to the complicated
thromboplastin generation test.
This neglect of the partial thromboplastin
time technic has stemmed partly from the
lack of a commercially available partial
thromboplastin and partly from a failure to
obtain short clotting times consistently with
normal plasma in some laboratories. Waaler12
has demonstrated that long times with normal plasma may be caused by inadequate
contact activation of the test plasma when
Received, J a n u a r y 24, 1961; revision received,
April 4; accepted for publication M a y 31.
D r . Proctor is Instructor in Medicine; D r .
R a p a p o r t is Associate Professor of Medicine.
Presented in p a r t a t t h e Southern California
Regional Meeting of the American College of
Physicians, Santa Barbara, California, F e b r u a r y
4, 1961.
Aided by grants from the Leukemia Research
Foundation, Los Angeles, California, and from
the National I n s t i t u t e of Arthritis and Metabolic
Diseases, Bethesda, Maryland (A-2989).
California
improperly washed glass clotting tubes are
used.
This paper deals with a technic for determining a standardized partial thromboplastin time, in which activation has been
made independent of the surface of the test
tube by Margolis' technic3 of providing
optimal contact activation with kaolin
powder. Data are included with reference to
2 partial thromboplastins, a "cephalin"
reagent made by extracting tissue from the
human brain with ether4 and a chloroform
extract made according to the instructions of
Bell and Alton.1 The latter was used because
any laboratory can prepare it easily from
commercially available rabbit brain thromboplastin.
MATERIALS AND METHODS
The Standard Screening PTT with Kaolin
Three reagents are required for the test.
1. Test plasma. Venous blood is obtained
from a clean venipuncture with a singlesyringe technic. Monocote (Armour Laboratories)-treated needles and silicone (SC-87
Drifilm, General Electric)-treated syringes
are used. Nine volumes of blood are added to
1 volume of anticoagulant solution in polyethylene tubes. The anticoagulant is made
by mixing 2 parts of 0.1 M citric acid with 3
parts of 0.1 M sodium citrate. (This is the
routine anticoagulant in our laboratory because it prevents the pH value of plasma
from rising on storage; inasmuch as the PTT
uses fresh plasma, 0.1 M sodium citrate alone
would serve as an equally satisfactory anticoagulant.)
Platelet-poor plasma is obtained by means
of centrifugation at 10,000 r.p.m. for 10 min.
in a Servall SS-1 centrifuge at 4 C. Any technic of centrifugation should prove satisfactory, inasmuch as the platelet concen-
212
Sept.
1961
PARTIAL THROMBOPLASTIN
TABLE 1
T H E LACK OF I N F L U E N C E OF THE P L A T E L E T C O N TENT OF T H E T E S T
PLASMA ON T H E P A R T I A L
THROMBOPLASTIN T I M E W I T H K A O L I N
Partial Thromboplastin Time with B and A
Extract-Kaolin.
1
2
Platelet Rich
Plasma*
Platelet Poor Plasmaf
Mixturet
sec.
sec.
sec.
43
38
42
37
43
37
* Centrifuged at 800 r.p.m. in an International
clinical centrifuge.
t Centrifuged at 10,000 r.p.m. in a Servall SS-1
centrifuge.
t A mixture of equal parts of 1 and 2.
tration of the test plasma does not influence
the PTT with kaolin, as indicated in Table 1.
Although we standardized the test using
silicone technic for the preparation of the
test plasma, there are no theoretic reasons
why the test could not be standardized,
using untreated needles and glass syringes,
if it were performed promptly after obtaining the blood samples. This point was
checked in 5 apparently normal persons.
Blood was taken in 2 syringes from the same
venipuncture site. The first syringe was
silicone-coated; the second syringe was glass.
The first sample was handled with silicone
technic until tested; the second sample was
further exposed to glass surfaces during
preparation of the plasma for testing. The
total time from drawing the samples to completing the tests was 2)4 hr. As is indicated
by the data in Table 2, there was not a significant difference in the P T T with kaolin
of the 2 samples in any subject.
2. Partial thromboplastin-kaolin reagents.
Stock "cephalin" reagent, an ether-soluble
extract of human brain tissue, is prepared as
described elsewhere.4 Inasmuch as it will
not be widely used, details of its preparation
will not be repeated.
Stock Bell and Alton chloroform extract
(B and A extract) 1 is made by adding 25 ml.
of reagent-grade acetone to the contents of 8
vials (150 mg. each) of rabbit brain thromboplastin (Bacto-Thromboplastin, Difco Laboratories). The mixture is allowed to stand
213
TIME
for 2 hr. at room temperature and is then
centrifuged at full speed for 5 min. in an
International clinical centrifuge. The supernatant fluid is discarded.
The residue is dried at room temperature
and the dried material is suspended in 25
ml. of chloroform in a stoppered flask that
is continuously agitated for 2 hr. It is then
filtered through filter paper and the precipitate is discarded.
The clear yellow filtrate is placed in a
100-ml. beaker and allowed to evaporate at
room temperature. The gummy, dark yellow
residue is scraped from the bottom of the
beaker and homogenized in 12 ml. of physiologic saline solution, using a glass tissue
grinder. A fine milky suspension forms
within 2 to 3 min.
This suspension is stored frozen at —20 C.
in 0.5-ml. lots as the stock extract. It stands
frozen indefinitely without loss of activity.
Furthermore, the same aliquot can be frozen
and thawed repeatedly without loss of activity.
Stock kaolin suspension is made by suspending 2 Gm. of kaolin powder (China
Clay, Braun Chemical Co.) in 50 ml. of
physiologic saline solution. It is stored in a
glass bottle at room temperature. I t must
be mixed thoroughly immediately before use.
The partial thromboplastin-kaolin reagent
is made by mixing equal aliquots of diluted
stock partial thromboplastin and stock
kaolin reagent. The dilution of stock partial
thromboplastin to use is determined whenever new stock reagent is made; it is obTABLE 2
A COMPARISON OF T H E P A R T I A L THROMBOPLASTIN
TIMES
WITH
WITH
KAOLIN
OF PLASMA
PREPARED
SILICONE T E C H N I C AND O F PLASMA E X -
POSED TO G L A S S
SURFACE
P a r t i a l Thromboplastin Times with B
and A Extract-Kaolin
Patient
1
2
3
4
5
"Silicone" plasma
" G l a s s " plasma
sec.
sec.
37
37
37
38
39
36
38
38
38
38
214
PROCTOR AND
served by measuring the PTT of normal
plasma with varying dilutions of stock
reagent between 1:25 and 1:200.
In order to make our B and A extractkaolin reagent, an initial 1:50 dilution of
stock B and A extract is made by adding 0.1
ml. of stock B and A extract to 4.9 ml. of
Veronal buffer (sodium diethylbarbiturate,
11.75 Gm.; sodium chloride, 14.67 Gm.; 0.1
N HC1, 430 ml.; and distilled water to 2000
ml.). Equal aliquots of the diluted B and A
extract and stock kaolin suspensions are
then mixed in order to give a final reagent
consisting of B and A extract diluted 1:100
in 20 mg. per milliliter of kaolin suspension.
3. Calcium chloride. A 30-mM solution is
made by diluting a 1 M aqueous stock solution with distilled water.
In order to perform the test, 0.2 ml. of the
partial thromboplastin-kaolin reagent is
pipeted into a 12- by 75-mm. glass clotting
tube. Inasmuch as kaolin settles rapidly, the
reagent must be mixed thoroughly (preferably by blowing through the pipet) immediately before pipeting. Then, 0.2 ml. of test
plasma is added to the clotting mixture and
the clotting tube is incubated at 37 C. for
3 min.
The prewarmed calcium is then added and
a stop watch is started. The tube is shaken
once immediately after adding the calcium
and returned to the incubator block. Thirty
seconds after adding the calcium and at successive 5-sec. intervals, the tube is picked
up and tilted gently. The end point, which is
read against a glass mirror with a strong
overhead light, is taken as the first clumping
of the kaolin. This is followed almost immediately by the formation of a solid clot. Tests
are performed in duplicate, averaged, and
the clotting times are rounded off to the
nearest half-second.
The Four-Component PTT
If a long screening PTT is observed, a 4component PTT may be performed next in
order to determine which reagent, adsorbed
plasma, or normal serum, shortens the time.
The additional "correcting" reagents for
the 4-component test are prepared as
follows:
1. Diluting fluid. Six hundred milliliters
RAPAPORT
Vol. 36
FIG. 1. The distribution of the partial thromboplastin time (PTT) with kaolin in a normal
adult population. K-B & A represents the B
and A extract reagent; K-C represents the
"cephalin" reagent.
of 0.9 per cent sodium chloride solution are
mixed with 200 ml. of 0.025 M sodium citrate
solution (prepared by adding 50 ml. of 0.1
M sodium citrate to 150 ml. of distilled
water) and with 200 ml. of Veronal buffer.
2. Adsorbed plasma. Aluminum hydroxide
gel (Cutter Laboratories) is diluted 1:4 with
distilled water and 0.1 ml. of this diluted
suspension is added to 1 ml. of fresh, normal
human citrated plasma. After 3 min. at 37
C. the aluminum hydroxide is removed by
means of centrifugation. Adsorbed human
plasma must be used fresh. Barium sulfateadsorbed, oxalated ox plasma may be used in
place of the human plasma.6 It has the advantage of standing up on storage at — 20 C.
3. Normal serum. Clotted blood is allowed
to stand for 2 hr. in a glass tube at 37 C.
Then, 0.1 M sodium citrate is added in the
ratio of 1 part of anticoagulant to 9 parts of
blood, and the tube is allowed to stand for 2
hr. more at 37 C. The citrated serum is
separated by means of centrifugation. It may
be used fresh or stored in small aliquots at
- 2 0 C.
In order to perform the 4-component test,
Sept. 1961
PARTIAL THROMBOPLASTIN
215
TIME
-K-C
-K-B&A
0100
-K-C
-K-B&A
100
80
g
i/) 8 0
I 60
i
=5*=.
40
60
I 40
c
20 10
_1_
_J
I
L_
20 30 4 0 5 0
%AHG
"TOO
20 -_,
X)
J 1_
20 30 40 50
°/o PTC
D1
100
F I G . 2 (left). A plot of clotting times against calculated levels of antihemophilic globulin (AHG)
in mixtures of normal and AHG-deficient plasma. K-B & A represents t h e B and A extract reagent;
K-C represents the "cephalin" reagent. The short vertical lines indicate t h e calculated level at
which t h e clotting time exceeds t h e upper limit of t h e normal range.
F I G . 3 (right). A plot of clotting times against calculated levels of plasma thromboplastin component (PTC) in mixtures of normal and PTC-deficient plasma. K-B & A represents t h e B and A
extract reagent; K-C represents t h e "cephalin" reagent. The short vertical lines indicate t h e calculated level at which the clotting time exceeds the upper limit of the normal range.
0.2 ml. of a "correcting" reagent is added to
3 pairs of clotting tubes. Diluting fluid alone
is added as a control to the first pair; adsorbed plasma diluted 1:5 in diluting fluid
is added to the second pair; and normal
serum diluted 1:5 in diluting fluid is added
to the third pair. The test is then performed
exactly as described above for the screening
PTT.
The AHG assay used in this laboratory is
a modification of the Pool-Robinson assay
and has been described in detail elsewhere.6
The PTA assay is based upon the ability of
a test plasma to correct the prolonged PTTkaolin time of a known PTA-deficient substrate plasma; it has also been described
elsewhere.9 A modification of Stapp's PTC
assay was used.11
RESULTS
The Normal Range
The PTT's with kaolin of 40 apparently
normal adults (20 men and 20 women bebetween the ages of 22 and 42 years) were
measured. The range for the "cephalin"kaolin reagent fell between 39.0 and 52.5
sec; the mean was 44.5 ± 3.0 sec. Slightly
shorter times were obtained with the B and
A extract-kaolin reagent. The normal range
was 35.0 to 44.5 sec. with a mean of 39.5 ±
2.0 sec.
The individual values have been plotted
on probability paper against standard devia-
tions from the mean in Figure 1. The reasonable linearity of the plots is consistent with
sampling from a homogenous population.
Therefore, we have set the upper limit of
normal at + 3 standard deviations, which
would include 99.7 per cent of a normally
distributed population. This is 53.5 sec. for
the "cephalin"-kaolin reagent, and 45.5 sec.
for the B and A extract-kaolin reagent.
These upper limits are much shorter than
our previously reported upper limit of 90
sec. for the PTT, 6 and the normal mean of
76 ± 13 sec. reported by Rodman and coworkers.10 This reflects the optimal surface
activation of the test plasma which is produced by adding the kaolin powder.
Sensitivity
The sensitivity of the PTT with kaolin to
deficiencies of the plasma thromboplastic
factors was evaluated in 2 ways. In the first,
the PTT with kaolin of mixtures in vitro of
normal plasma (called 100 per cent) and
severe specific deficiency plasmas (called 0
per cent) were measured. Figures 2 through
5 are plots on log-log paper of the clotting
times vs. the calculated levels of the deficient plasma thromboplastic factors in
these mixtures. With the "cephalin"-kaolin
reagent the clotting time exceeded the upper
limit of normal cited above, when the calculated level of AHG fell below 50 per cent, the
level of PTC below 30 per cent, the level of
216
Vol. 36
PROCTOR AND RAPAPORT
— K-C
—K-B&A
•nlOO
° 80
60
60
P 40 -
40
20
10
20
304050
a K-C
.—K-B&A
00
80
—1
100
r,u 20
~"*" : : : : -- : 8 : f^^-
-
i
i
i
10
%
20
HF
i
i
i
30 4 0 5 0
i
100
FIG. 4 (left). A plot of clotting times against the calculated levels of plasma thromboplastin
antecedent (PTA) in mixtures of normal and PTA-deficient plasma. KB & A represents the B and
A extract reagent; K-C represents the_"cephalin" reagent. The short vertical lines indicate the
calculated level at which the clotting time exceeds the upper limit of the normal range.
FIG. 5 (right). A plot of clotting times against the calculated levels of Hageman factor (HF) in
mixtures of normal and HF-deficient plasma. K-B & A represents the B and A extract reagent;
K-C represents the "cephalin" reagent. The short vertical lines indicate the calculated level at
which the clotting time exceeds the upper limit of the normal range.
PTA below 25 per cent, and the level of H F
below 25 per cent. With the B and A extractkaolin reagent the clotting times exceeded
normal when AHG fell below 50 per cent,
PTC below 35 per cent, PTA below 40 per
cent, and HF below 30 per cent.
The second way in which sensitivity was
evaluated was to compare the PTT with
kaolin of plasma from patients with hemophilia and the hemophilioid states with the
levels of the deficient factors, as measured in
quantitative assays. These data are listed in
Table 3.
The prime requisite of a satisfactory
screening test for first stage plasma-clotting
factor deficiencies is that it detects without
fail the patient with mild hemophilia A or B,
i.e., the patient whose level of AHG or PTC
lies between approximately 10 and 30 per
cent of normal. Note that several such patients are listed in Table 3; all had clearly
abnormal partial thromboplastin times.
W.N., whose AHG level is 17 per cent, is a
good example of a mild hemophiliac person.
He is a physician in whom a pulmonary resection for tuberculosis was being seriously
contemplated, despite a history of excessive
bleeding after a dental extraction. His
clotting time was reported as normal in
another laboratory; in our laboratory, it was
very slightly prolonged. In contrast, his
screening PTT with kaolin clearly established that he had a significant plasmaclotting factor defect.
M. H. is an example of a patient with
vascular hemophilia, a disorder characterized by a long bleeding time associated with
a deficiency of AHG, which may vary from
a very mild to a profound deficiency. His
AHG deficiency is very mild; his value of
47 per cent AHG falls just below the lower
limit of normal for our laboratory (normal
AHG range, 52 to 133 per cent). This degree
of AHG deficiency probably does not contribute to his bleeding tendency for we have
seen many carriers of hemophilia A with
AHG levels between approximately 35 and
50 per cent of normal who have not bled
abnormally.7 The important point to note is
that his PTT with kaolin, using the B and A
extract, just exceeded the upper limit of
normal. This observation reinforces the
evidence provided by the patients with mild
hemophilia A that the PTT with kaolin will
not miss the patient with a clinically significant deficiency of AHG, i.e., the patient
with less than 30 per cent of normal.
The carriers of hemophilia B listed in
Table 3 provide evidence of the sensitivity
of the PTT with kaolin to clinically significant deficiencies of PTC. Carrier D. H., the
sister of a severe hemophiliac person, complained that she also bled abnormally. Her
PTT with kaolin was definitely prolonged;
her PTC level was 21 per cent. In contrast,
carrier D. S. R., whose PTC level of 40 per
cent is outside the range of abnormal bleed-
TABLE 4
TABLE 3
A
COMPARISON
TIMES
OF PARTIAL
AND QUANTITATIVE
THROMBOPLASTIN
ASSAYS
CORRECTION
TIAL THROMBOPLASTIN
FOR A N T I -
COMPONENT
THROMBOPLASTIN
PLASMA
FROM
(PTC),
GREES O F SPECIFIC
Disorder
WITH
Vascular
hemophilia
L. B .
D . V.
G. T .
J. B .
F. H.
P. R.
M . R.
D . R.
W. N .
M. G.
D . R.
M. H .
3
3
4
8
9
10
14
16
17
17
30
47
normal
<S3.S
sec.
normal
<45.S
sec.
115.0
100.5
86.0
65.5
62.0
68.5
68.5
68.0
60.5
62.5
69.5
51.5
101.0
74.5
76.5
58.0
54.5
79.0
70.5
74.0
51.5
51.5
58.0
47.0
]
PTC
Hemophilia B
Female carriers of
hemophilia B
J. G.
T. H.
W. M.
E. F .
D. H.
D . S. R .
3
7
11
11
21
40
96.5
92.5
66.0
65.0
59.0
51.0
86.0
77.0
53.0
61.0
52.0
45.0
131.5
115.0
95.0
112.0
87.5
95.0
93.0
84.0
90.5
87.5
102.0
89.5
53.5
52.5
56.6
55.0
48.5
47.0
121.5
107.0
87.0
102.0
82.0
87.0
92.0
78.0
82.0
77.0
97.0
77.0
47.5
49.5
52.0
47.0
44.0
46.0
364.0
448.0
PTA
Major P T A
deficiency
Minor PTA
deficiency
R. K.
D . G.
J. L.
S. S.
M. M .
S. L.
G.J.
E. G.
E. F .
L. J .
F . M.
M. T .
M. J .
F. B.
R. L .
M. L.
J. L.
H . G.
3
4
4
6
7
8
8
8
10
10
12
12
33
36
38
39
40
43
HF
Hageman factor
deficiency
N. E.
<1
THROMBOPLASTIN
Partial Thromboplastin Time with
IN
P a r t i a l Thromboplastin Time
Per
(Sec.) with
cent
"Cephalin"Factor Kaolin and B and
A ExtractKaolin
AHG
Hemophilia A
(PTA)
VARYING D E -
Patient
Deficiency
Diluting
fluid
DEFICIENCIES
Patient
PAR-
( P T T ) USING T H E
AND PLASMA
ANTECEDENT
PATIENTS
TIME
B AND A EXTRACT P A R T I A L
HEMOPHILIC G L O B U L I N ( A H G ) , PLASMA T H R O M BOPLASTIN
STUDIES IN THE 4-COMPONENT
Adsorbed
plasma*
Serum*
sec.
sec.
sec.
D . V.
J. B .
W. N .
AHG
AHG
AHG
85.5
74.0
57.0
44.5
44.0
39.0
84.0
71.0
51.5
J. G.
T. H .
E. F .
PTC
PTC
PTC
95.0
88.0
68.0
85.5
83.0
60.5
52.0
51.5
53.5
S. S.
G. J .
M. T .
PTA
PTA
PTA
117.5
100.0
78.0
83.0
76.5
58.0
70.5
69.0
57.5
* Diluted 1:5 in diluting fluid.
ing, had a partial thromboplastin time at the
upper limit of normal.
Recently we reported8 that PTA deficiency exists in 2 forms; homozygous or
major PTA deficiency and heterozygous or
minor PTA deficiency. Major PTA deficiency is a hemorrhagic disorder in which
PTA levels between 3 and 20 per cent of
normal are associated with the potential
for serious bleeding after surgery or dental
extraction. As the data in Table 3 indicate,
these patients all have greatly prolonged
PTT's with kaolin.
In contrast, minor PTA deficiency is a
clinically insignificant disorder which exists
in the parents and children of patients with
major PTA deficiency. Most of these persons give no history of abnormal postoperative or postextraction bleeding. An occasional patient will describe an episode of
bleeding that might be interpreted as abnormal but not as serious, e.g., a brief episode
of bleeding from a tooth socket on the second
day after a dental extraction. These persons
have PTA levels above 30 per cent of normal.
As the data reveal, their clotting times with
B and A extract are usually slightly prolonged. With the "cephalin" reagent, the
values overlap the upper limit of normal.
In summary, the data in Table 3 parallel
the data obtained from the in vitro mixtures
and indicate that the P T T with kaolin
readily detects clinically important de217
218
PROCTOR AND
ficiencies of each of the plasma thromboplastic factors.
The Four-Component PTT
The characteristic screening findings in a
first stage plasma-clotting factor disorder
are (1) a normal screening test for the extrinsic coagulation reactions, i.e., a normal
Quick "prothrombin time" coupled with (2)
an abnormal screening test for the intrinsic
coagulation reactions, i.e., a prolonged
screening PTT with kaolin. A clue to the
specific defect may be obtained quickly by
noting which added reagent—adsorbed
plasma or serum—shortens the prolonged
time in a 4-component PTT.
Approximately 80 per cent of patients
with a first stage disorder will turn out to
have hemophilia A.6 As indicated in Table 4,
their prolonged 4-component PTT's will
be completely corrected by a 1:5 dilution of
adsorbed plasma; diluted serum will not
shorten the control time significantly.
Approximately 20 per cent of the patients
will turn out to have hemophilia B. Their
4-component PTT's will be shortened almost
to within normal limits by a 1:5 dilution of
serum; adsorbed plasma will have little
effect.
Rare patients with PTA deficiency will be
observed. They will reveal partial correction
with both adsorbed plasma and serum.
Although strongly suggestive of the diagnosis, the correction patterns revealed in
Table 4 are not final proof of the specific
deficiency. This rests either upon quantitative assay of the missing factor or upon cross
correction experiments with known prototype deficiency plasmas.
DISCUSSION
There has been a need for a simple, reliable, sensitive, one-stage screening test for
hemophilia and the hemophilioid disorders
that can be used in any well supervised
routine clinical laboratory. The data presented above reveal that the PTT with
kaolin meets these requirements.
Although the original P T T technic of
Langdell and associates2 has proven its usefulness in screening large hemophilic populations, 6, 10 it contains the uncontrolled vari-
Vol. 36
RAPAPORT
able of a suboptimal and unpredictable
contact activation of the test plasma. Contact activation depends entirely upon the
surface characteristics of the glass tubes used
for storing and testing the test plasma; this,
in turn, depends upon the technic of washing
the glassware.12
Adding kaolin powder to the clotting mixture, a suggestion first advanced by
Margolis,3 provides a standard, optimal
contact activation of the test plasma. It
eliminates the need for special washing
technics for test tubes and removes a
troublesome variable from the test. It
greatly shortens the PTT of normal plasma
and narrows the limits of the normal range.
As the data presented above clearly indicate, optimal contact activation does not
impair the sensitivity of the test. The PTT
with kaolin of plasma containing less than
approximately 30 per cent of normal of
AHG, PTC, PTA, or HF exceeds the upper
limit (3 standard deviations) of the normal
range. Therefore, the test will detect the
patient with a clinically significant deficiency of a plasma thromboplastic factor;
in particular, it will discover the "mild
hemophiliac."
The data also indicate that the chloroform
extract of Bell and Alton is slightly superior
to the "cephalin" preparations that were
originally used as the partial thromboplastin. 6 ' 10 Inasmuch as the chloroform extract can be made simply from commercially
available rabbit brain thromboplastin, there
are no practical deterrents to the widespread use of the test. A clinical laboratory
can prepare enough reagent in 1 day to last
for many months.
In addition to its usefulness in diagnosis,
the PTT with kaolin can be used in evaluating replacement therapy in hemophilia.
By making a curve of mixtures in vitro of
normal and patient's plasma (as illustrated
in Figs. 2 to 5) and relating the patient's
PTT with kaolin during replacement
therapy to this curve, one can quickly determine the effectiveness of replacement
therapy.
SUMMARY
This paper deals with the description of a
technic for determining a modified partial
Sept. 1961
PARTIAL THROMBOPLASTIN
thromboplastin time (PTT), in which optimal contact activation of the test plasma is
provided by adding kaolin powder to the
partial thromboplastin reagent. Data are
given for 2 partial thromboplastins, the
originally described "cephalin" preparation
and the chloroform extract of Bell and Alton
that has the advantage of being easily prepared from commercially available rabbit
brain thromboplastin.
The normal limits of the P T T with kaolin
are denned for an adult population. The
times of plasma containing less than approximately 30 per cent of normal AHG, PTC,
PTA, or H F have been demonstrated to exceed the upper limits of the normal range.
The test meets the requirements for a
reliable, sensitive, one-stage screening test
for hemophilia and the hemophilioid disorders. It is simple enough for use in any
well supervised routine clinical laboratory.
219
TIME
un fidel e sensibile test preliminari uniphasic
pro hemophilia e le disordines hemophilioide.
Illo es satis simple pro esser usate in le routine de un ben controlate laboratorio clinic.
Acknowledgment. We wish t o t h a n k Miss M a r y
Jane P a t c h for her technical help in some of these
studies.
REFERENCES
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Iste communication describe un methodo
pro determinar, sub forma modificate, le
tempore de thromboplastina partial (TTP)
in que optimal activation de contacto pro le
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addition de kaolin pulveriforme al reagente
de thromboplastina partial. Es citate datos
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Alton que ha le avantage que illo es facilemente preparate ab commercialmente disponibile thromboplastina de cerebro de
conilio.
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del plasma, antecedente de thromboplastina
de plasma, o de factor Hagemann excede le
limites superior del region normal.
Le methodo satisface le requirimentos pro
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