THE QUANTITATIVE ESTIMATION OE THE 
RENNET-ZYMOGEN: 
Its Diagnostic Value in Certain Diseases of the Stomach. 
BY 
JULIUS FRIEDENWALD, A.B., M.D., 
CLINICAL PROFESSOR OF DISEASES OF THE STOMACH, COLLEGE OF PHYSICIANS 
AND SURGEONS, BALTIMORE. 
FROM 
THE MEDICAL NEWS, 
June 22, 1895. [Reprinted from THE MEDICAL NEWS, June 22, 1895.] 
THE QUANTITATIVE ESTIMATION OF THE 
RENNET-ZYMOGEN; ITS DIAGNOSTIC 
VALUE IN CERTAIN DISEASES 
0 F THE S TOM AC H} 
By JULIUS FRI EDEN WALD. A.B., M.D., 
CLINICAL PROFESSOR OF DISEASES OF THE STOMACH, COLLEGE OF 
PHYSICIANS AND SURGEONS, BALTIMORE. 
The detection and the estimation of free hydro- 
chloric acid in the gastric contents are of consider- 
able importance in the diagnosis of diseases of the 
stomach, but conclusions based upon these facts 
alone may be wholly fallacious, as it is well known 
that mental conditions and various external influ- 
ences, as well as disturbances of the circulation, 
influence the secretion of hydrochloric acid. Not 
only marked changes in the mucous membrane, 
therefore, but also functional disturbances may 
cause diminution or absence of hydrochloric acid. 
Quantitative examinations for free hydrochloric 
acid give us but little knowledge of the degree of 
destruction of the gastric mucous membrane, for, 
while free hydrochloric acid is usually entirely 
absent in marked change of the mucous membrane, 
we frequently find the same condition when the 
1 Read at the annual meeting of the Medical and Chirurgical 
Faculty of Maryland, April 24, 1895. 2 
changes are but slight. It is, therefore, generally 
admitted that, in order to draw proper conclusions 
concerning the true condition of the stomach from 
examinations for free hydrochloric acid, the examin- 
ations should be frequently repeated. But even then 
we may still be in doubt as to whether there is a 
nervous anacidity, slight or marked catarrh, or a 
hyperemic condition of the stomach, secondary to 
diseases of some other organ. 
While such variations are found in regard to the 
secretion of hydrochloric acid, the secretion of the 
ferments, or rather of their zymogens, bears a defi- 
nite relation to the pathologic changes present. 
Boas has shown that external influences, as well 
as congestive conditions, have little effect on the 
secretion of these substances, and that a marked 
diminution in their quantity is aways indicative of 
some serious gastric lesion. The quantitative esti- 
mation of pepsin and its proenzyme has, until re- 
cently, been attended with great difficulty. Methods 
have been devised for this purpose by Boas,1 Johan- 
nessen,2 and others, but exact results cannot be 
obtained by any of these methods. It'is, therefore, 
necessary, in exact examinations, to test the peptic 
strength by weighing the fibrin before, and then 
again after partially digesting it in a given quantity 
of gastric juice. 
This method is quite complicated and wholly 
unsuited for practical purposes. A new method for 
1 Boas: Allgemeine Diagnostik und Therapie, 3. Auflage, S. 
187. 
2 Johannessen : Studienuber die Fermente des Magens, Zeit- 
schrift fur klin. Medicin, Bd. 17, H. 3 und 4. 3 
the estimation of pepsin, which is simple and 
seems to give exact results, has recently been de- 
vised by Hammerschlag.1 This method has not as 
yet been generally employed. 
The estimation of the rennet-ferment (lab) and 
its proenzyme (labzymogen) is very simple. The 
method usually employed is that of Boas: 
The detection of the milk-curdling ferment is as 
follows:2 Ten c.cm. of gastric filtrate are exactly 
neutralized with a y normal NaOH solution, and 
10 c.cm. of neutral milk are added, and the mixture 
placed in an incubator at 38° C. If the rennet- 
ferment is present, a casein-coagulum is formed in 
from ten to fifteen minutes. 
The detection of the rennet-zymogen is as fol- 
lows : 
To 10 c.cm. of gastric filtrate, made slightly alka- 
line, 2 c.cm. of a 1 per cent, solution of calcium 
chlorid are added, and then 10 c.cm. of milk, and 
the mixture placed in the thermostat. 
If the rennet-zymogen is present, a heavy cake of 
casein is precipitated in a few minutes. 
The quantitative estimation of the milk-curdling 
ferment is made as follows: A part of the gastric 
filtrate is exactly neutralized, and portions are 
diluted with distilled water (y y , etc.). Five 
c.cm. of each of these portions are placed in 
beakers, 5 c.cm. of neutral milk are added, and the 
mixtures placed in the thermostat. It can thus easily 
be determined at which dilution the ferment is no 
longer active. 
As to the quantitative estimation of the rennet- 
1 Hammerschlag: Ueber eine neue Methode zur quantitative 
Pepsinbestiumung. Internationale klin. Rundschau, Jahrg. viii., 
Sept. 1894, No. 59. 
2 Loc. cit., S. 188. 4 
zymogen, a part of the gastric filtrate is made slightly 
alkaline and portions diluted y’y, y 3T> 
etc.). To 5 c.cm. of each of these portions x c.cm. 
of a i per cent, solution of calcium chlorid is added, 
and 5 c.cm. of milk. The dilution can thus be deter- 
mined at which the rennet-zymogen is no longer 
active. 
By means of this method Boas has arrived at the 
following conclusions: 
1. In spite of the absence of free hydrochloric 
acid, the rennet-ferment may still be present, but 
only in small amount, in dilutions of from y*y to -^y. 
2. In the absence of free hydrochloric acid the 
zymogen may be present in normal amount, even in 
dilutions of from to yiy. The repeated 
demonstration of the normal proportion of the 
zymogen proves with great certainty that an or- 
ganic gastric disorder is not present, and that 
there is either a neurosis or a secondary gastric con- 
gestion. 
3. The zymogen may be diminished one-half. 
This is most frequently due to a catarrh of moderate 
intensity. The more nearly the zymogen reaches the 
normal the greater is the probability of entire re- 
covery under proper treatment. 
4. If the labzymogen is much diminished in 
quantity, e. g., Jy, or entirely absent, there is always 
a severe and incurable catarrh, which may be pri- 
mary, or due to another disease, as carcinoma, 
amyloid degeneration, etc. 
5. In the conditions represented by 1, 2, and 3, 
the secretion of hydrochloric acid may be increased 
by proper treatment. In the condition represented 5 
by 4, there is but little hope of renewing the secre- 
tion of hydrochloric acid. 
During several years I have as a routine practice 
made examinations of the gastric contents obtained 
one hour after an Ewald test-breakfast, to determine 
the activity of the milk-curdling ferment and its 
zymogen. It is to the result of these examinations 
that I wish to call attention. 
Of the cases selected from many hundreds only 
those have been tabulated in which at least three 
examinations were made. In order to reduce the 
tables still more I have omitted many cases giving 
results exactly similar to others already given. 
In Table I are represented the cases in which there 
was a normal percentage of free hydrochloric acid. 
There are here tabulated the results obtained from 
three normal cases, three cases of atony, a case of sim- 
ple dilatation, and three cases of nervous dyspepsia. 
In order to make the tables more intelligible, the 
points of dilution at which the milk-curdling fer- 
ment and its zymogen were still present are placed 
in full numbers in this as well as in the following 
tables. They should, therefore, read j for 12 ; fa 
for 50, etc. 
It is seen that the degree to which the milk- 
curdling ferment may be diluted is much less than 
that of its zymogen, for, while the former is never 
present in dilutions less than fa, its zymogen may 
at times be still distinctly recognized in dilutions 
°f T3TT- 6 
Table I.—Cases with Normal Percentage of 
Free Hydrochloric Acid. 
Number ot 
examination. 
Name. 
Disease. 
Total 
acidity. 
Per cent, of 
free HC1. 
Milk-curdling 
| ferment. 
Milk-curdling 
| zymogen. 
I 
F. j. 
Normal .... 
50 
0.175 
12 
150 
2 
64 
0.161 
15 
150 
3 
48 
0.148 
28 
IOO 
4 
E. F. 
Normal .... 
42 
O.139 
24 
75 
5 
46 
0.158 
22 
40 
6 
54 
0.149 
22 
50 
7 
J. M. 
Normal .... 
55 
0.169 
18 
80 
8 
Si 
0.160 
40 
25 
9 
5« 
0.154 
32 
150 
10 
F. B. 
Atony .... 
40 
0.143 
IO 
125 
II 
44 
0.145 
34 
75 
12 
42 
0.141 
1.5 
IOO 
13 
M. W. 
Atony .... 
48 
0.159 
18 
150 
M 
5° 
0.151 
15 
75 
15 
44 
0.139 
40 
50 
16 
L. P. 
Atony .... 
50 
0.148 
3« 
70 
17 
48 
0.139 
12 
125 
18 
55 
0.152 
40 
5° 
19 
H. k. 
Simple dilatation . 
68 
0.169 
12 
90 
20 
62 
0.165 
IO 
IOO 
21 
6.3 
0.160 
35 
55 
22 
H. T. 
Nervous dyspepsia . 
48 
0.142 
40 
35 
23 
44 
0.149 
12 
90 
24 
40 
0.134 
16 
IOO 
25 
K. S. 
Nervous dyspepsia . 
42 
O.I4O 
15 
125 
26 
44 
0.139 
40 
35 
27 
48 
0.134 
20 
ICO- 
28 
H. T. 
Nervous dyspepsia . 
50 
0.138 
18 
75 
29 
46 
O.I4I 
12 
150 
30 
40 
0.135 
24 
70 7 
Table II.—Cases with Increased and Diminished 
Percentage of Free Hydrochloric Acid. 
Number of 
examination. 
Name. 
Disease. 
Total 
acidity. 
Per cent, of 
free HC1. 
Milk-curdling 
ferment. 
Milk-curdling 
zymogen. 
I 
B. C. 
Supersecretion 
89 
0-305 
40 
5° 
2 
86 
0.302 
35 
45 
3 
82 
0.2Q7 
40 
25 
4 
J.A. 
Superseeretion 
98 
O.3OI 
32 
25 
5 
96 
0.302 
3° 
55 
6 
82 
O.289 
25 
IO 
7 
D. W. 
Superacidity; ulcer 
84 
0.286 
15 
25 
8 
89 
0.305 
25 
20 
9 
90 
O.3OI 
20 
3° 
IO 
P- J. 
Superacidity; nerv. dysp. 
90 
0.302 
20 
3° 
II 
89 
0.302 
20 
35 
12 
88 
O.298 
15 
3° 
13 
G. A. 
Superacidity; nerv. dysp. 
88 
O.3OI 
25 
IS 
14 
92 
0.302 
20 
20 
15 
98 
O.3IO 
15 
25 
l6 
F. L. 
Superacidity; nerv. dysp. 
92 
O.3OI 
15 
20 
17 
89 
O.29S 
20 
55 
18 
86 
0.302 
35 
45 
19 
F. k. 
Subacidity ; nerv. dysp. . 
3° 
o.oc,8 
35 
3° 
20 
28 
0.084 
20 
35 
21 
26 
0.082 
IO 
4° 
22 
J- D. 
Subacidity ; nerv. dysp. . 
24 
0.081 
25 
40 
23 
28 
0.086 
25 
20 
24 
29 
0.089 
IO 
25 
25 
S. F. 
Chronic gastritis 
34 
0.102 
20 
50 
26 
26 
O.O9I 
12 
40 
27 
24 
0.084 
14 
35 
28 
K. M. 
Chronic gastritis 
34 
0.096 
18 
25 
29 
3« 
O.O99 
12 
20 
3° 
36 
O.IO4 
14 
25 
31 
L. P. 
Chronic gastritis 
37 
0.098 
IO 
25 
32 
34 
0.098 
14 
20 
33 
32 
O.O92 
20 
15 8 
In Table II are represented the cases with increased 
or diminished percentage of free hydrochloric acid. 
There are two cases of supersecretion, a case of 
superacidity due to ulcer, two cases of nervous dys- 
pepsia, all with marked superacidity, besides three 
cases of subacidity (nervous dyspepsia), and three 
cases of chronic gastritis with subacidity. 
The milk-curdling ferment is not found in dilu- 
tions beyond ; its zymogen may be present in 
dilutions of from to y1^. 
In Tables III A and III B are found the cases of 
nervous dyspepsia and secondary gastric disturb- 
ances, with entire absence of free hydrochloric acid. 
It is seen that while the ferment may be markedly 
diminished, its zymogen may still be present in 
dilutions of from to giy. 
Table III.—Gastric Disturbances in which there 
is an Absence of Free Hydrochloric Acid. 
A. Nervous Dyspepsia. 
G\Ln [0 h 
No. of exami- 
nation. 
K. T. 
J-s. 
Name. 
tO M M M 
O to to M 00 
Total acidity. 
Cn tn w Cn 00U\ 
Milk-curdling 
ferment. 
tin oovj ONVl O 
O O O O Cn O 
Milk-curdling 
zymogen. 
to m O vO 00 vj 
No. of exami- 
nation. 
P. L. 
f.’m. 
Name. 
M to to M M 
00 to O O to 00 
Total acidity. 
00 Cn to 0 tn tn 
Milk-curdling 
ferment. 
8o 
no 
13° 
IOO 
80 
60 
Milk-curdling 
zymogen. 9 
B. Secondary Gastric Disturbances (Hyperemic Condition ot 
Stomach). 
No. of 
exami- 
nation. 
Name. 
Primary disease. 
Total 
acidity 
Milk- 
curdling 
ferment. 
Milk- 
curdling 
zymogen. 
X 
K. F. 
Pulmonary tuberculosis 
8 
s 
75 
2 
12 
8 
80 
3 
IO 
S 
75 
4 
L. F. 
Pulmonary tuberculosis 
15 
5 
65 
5 
14 
IO 
75 
6 
8 
8 
lOO 
7 
P. M. 
Pulmonary tuberculosis 
12 
S 
120 
8 
IO 
12 
80 
9 
14 
5 
65 
IO 
J. P. 
Heart-disease 
20 
l6 
150 
II 
12 
5 
75 
12 
IO 
8 
150 
13 
J. F. 
Heart-disease 
14 
IO 
75 
14 
IO 
IO 
IOO 
15 
14 
is 
80 
l6 
w.'s. 
Heart-disease 
18 
14 
IOO 
17 
9 
8 
150 
18 
is 
IO 
80 
C. Chronic Gastritis. 
Cn-£u> 10 m O vO OO'O OMn 4- CO to h 
No. of exami- 
nation. 
. . . os. . y>. . o. . w 
5® y SC 
Name. 
Total acidity. 
LnCn to O O 00 Cn u\ Cn to O Cn O CO Cn. 
Milk-curdling 
ferment. 
MtOCOtOtOtOMOOMtO H to to 
Cn O Cn O Cn O Cn O O Ln Ln Lr\ O Ln O 
Milk-curdling 
zymogen. 
tOtOtOtOtOtOtOtOMMMM 
'O CKn CO to M O vO oov} Q\ 
No. of exami- 
nation. 
V. . O. . § 
• • ■■?»■• 5»- ■ 
Name. 
oooooooooooo 
Total acidity. 
oooooooooooo 
Milk-curdling 
ferment. 
W Cn in vj Ui S OiCn 0 Cn Cn 
Milk-curdling 
zymogen. 10 
In Table III C we have represented cases of 
chronic gastritis. The milk-curdling ferment is 
much diminished (even to o), the zymogen between 
-gy- and In cases of carcinoma, Table III D, the 
milk-curdling ferment is diminished, its zymogen 
reduced to from to y’y. 
D. Carcinoma. 
to M o VO 00V3 OnLn LO to m 
No. of exami- 
nation. 
. . to . Ti. . . a 
H p n co 
Name. 
tOWMMWWWWM 
HVO to 4* to O ON4> 00 
Total acidity. 
00 OO Ln La La CO to La La O 00 O 
Milk- curdling 
ferment. 
to to to to to lOWW to H to w 
La La O O La La La 0 La La O O 
Milk-curdling 
zymogen. 
tOtOtOtOtOMMMMMMM 
Lo to M 00 v} ON La 4*- LO 
No. of exami- 
nation. 
. . C/3 f O . 
r h g r 
Name. 
00 o to O 00 00 ON 00 to to 4- Ln 
Total acidity. 
Ln La 00 00 La La La to O O O La 
Milk-curdling 
ferment. 
LO LO LO LO LO tO 4* LO LO 4* LO 
O La La O La O La O La La OLa 
Milk-curdling 
zymogen. 
We have thus shown that in conditions in which 
the free hydrochloric acid is absent, but in which 
there is no pathologic change in the stomach, such 
as in nervous dyspepsia and secondary gastric 
catarrh, the zymogen is still present in dilutions 
ranging between and In those conditions, 
however, in which there are structural changes in 
the gastric mucous membrane, such as in chronic 
gastric catarrh and carcinoma, the zymogen is 
markedly diminished depending upon the 11 
severity of the disease. The more nearly the zymo- 
gen reaches the zero-point the greater the destruc- 
tion of the gastric mucous membrane, and the less 
the chance for complete recovery. 
Our conclusions may be summed up as follows: 
1. Under normal conditions the milk-curdling 
ferment may be present in dilutions the 
zymogen up to T^. 
2. In those cases in which there is a normal or 
diminished percentage of free hydrochloric acid, 
the milk-curdling ferment and its zymogen may be 
present in normal quantities or may be markedly 
diminished. Their estimation, therefore, in these 
cases is of little value. 
3. The estimation of the milk-curdling ferment 
and its zymogen is of great diagnostic as well as 
prognostic importance in those cases of gastric dis- 
order accompanied by an entire absence of free 
hydrochloric acid. In these cases (chronic gas- 
tritis or carcinoma) there is marked diminution of 
the zymogen (^-0)> depending upon the severity 
and extent of the disease. In cases of nervous dys- 
pepsia, as well as in secondary catarrh, the zymogen 
is present in normal proportions in dilutions of from 
Tlhr to rV We can, therefore, readily determine 
whether there is actual disease of the gastric mucous 
membrane or simply a nervous or congestive condi- 
tion. 
4. In those cases in which there is an absence of 
free hydrochloric acid, and in which the labzymogen 
falls between g- and it is impossible to deter- 
mine at once whether there is a catarrhal condition 
or nervous dyspepsia present. Several examinations 12 
must be made to determine whether the labzymogen 
ranges above g or below 
5. In cases of chronic gastritis the examination 
for the labzymogen is of considerable prognostic 
importance. In those cases in which the labzymogen 
is diminished from T to o there is no chance of 
recovery; in those in which it is diminished from 
to to 30 there is a possibility that judicious treatment 
may result in recovery. The Medical News. 
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