By PETER I. ZEEDICK, M. D.
Epidemic influenza, unlike other acute infectious processes as
diphtheria and scarlet fever, seemingly attacks the kidney in a rather
mild manner. This statement refers only to the uncomplicated cases, as
other bacterial or toxic agents do play a part in the nephritides
occurring so often with the pneumonias or other complications
following influenza. It is, however, true that in many simple epidemic
cases there is evidence of a transient mild nephritis, or possibly,
more correctly stated, a nephrosis. Some writers observed albuminuria
in 80 per cent. of the cases, while the incidence in other reports
varies from 4 to 66 per cent. It is not always stated with reference
to these figures that the patients clinically were free from the
common complication—pneumonia. The findings of various observers
differ greatly, but they all agree that acute nephritis as a serious
sequel is somewhat rare.
In the literature of the past epidemics general acknowledgment has been
accorded to the presence of albumin in the urine during the acute stage
of the disease. Many times this has received no further notice or
comment than “febrile albuminuria.” The association of occasional
hyaline and granular casts has also been mentioned. One is impressed
with the fact that the older observers laid but little emphasis on the
urinary findings. It also seems to be true that nephritis as a clinical
entity is not prone to follow the epidemics. In general, our conclusions
from the last epidemic are about the same.
The data for this paper was obtained from examination of 994 specimens
of urine from 750 patients; of this number 517 specimens were examined
at the Magee Hospital, where members of the S. A. T. C., all young men,
were treated, and 447 specimens from the Mercy Hospital, where, in
addition to the S. A. T. C., we had men, women and children. On account
of the large amount of material and work on hand, as a rule only one
specimen of urine was examined from each patient, but where
complications were suspected repeated daily examinations were made. We
have grouped our results in tables, so that the various points may be
more readily followed.
Table I shows the urinary findings of uncomplicated influenza cases
admitted to the wards of the Mercy Hospital. None of these cases
developed pneumonia and, after running the usual course, recovered. We
would call attention to the fact that 25 per cent. showed albuminuria.
The amount of albumin was never excessive, and very often was little
more than a faint trace. On the other hand, we have had a few patients
where a previous kidney lesion was known to be present, and naturally in
these cases a heavy cloud of albumin was met with. The albuminuria was
almost always a transient affair, lasting only during the acute part of
the illness, and would rightly come under the class of febrile
albuminuria. We regard it as being more the evidence of nephrosis than a
nephritis. As a rule, the time for the appearance of albumin was after
the fever had been present for at least two or three days. One rarely
met with it in the short attacks of influenza where the temperature came
to normal in less than 72 hours. A certain time factor appeared to be
necessary in order for the nephrosis to develop. Another point of
interest is the presence of red and white blood cells seen relatively
frequently during the early days of the illness. One wonders if this
finding is analogous to the bleeding from the nose and lung so often met
with at the onset of the disease. The red blood cells were seen
microscopically, and only very rarely did we encounter a smoky urine.