In the diagnosis of any given case it is well to outline the points to be determined, then carefully to weigh them one against the other in the final analysis. Roughly the subject divides itself into a consideration of (a) the general physical condition; (b) the urinary findings; (c) the cardiac adequacy; (d) the arterial involvement; (e) the bloodpressure picture; (f) the renal functional efficiency; and (g) the ocular manifestations.

(a) The General Physical Condition. Much can be determined by a careful physical examination and a thorough history that throws light upon the patient's general efficiency, including mentality, assimilation, nurtrition, and general muscular development.

(b) The Urinary Findings.-In parenchymatous nephritis the urine picture is very similar to that of acute Bright's disease in which the amount of urine is scant, of high specific gravity, with a relatively large albumin content, a variety of casts; and differing from it only in the usual absence of blood casts, though there may be an occasional red cell, together with hyaline and epithelial casts. Chronic interstitial nephritis and contracted kidney show increased volume of urine with low specific gravity, a scant or absent albumin reaction, while hyaline and granular casts are usually found, if diligently sought, but are often overlooked in routine examination. In the examination of single specimens occasional red cells and epithelia may be found.

(c) Cardiac Efficiency.-The functional capacity of the kidneys in cases coming under this head is almost entirely dependent upon cardiac efficiency, as measured by the ability of the heart to maintain a normal circulation against

the elevated blood-pressure which is the result of general arterial involvement including its immediate effect on heartmuscle nutrition. A high pressure with extensive arterial involvement may present a better picture in the presence of an hypertrophied and muscularly competent heart than 19/12| | |1912/19/3 | | 1974 |19/5/19/16

FIG. 60.-Female. Aged fifty-eight. High-grade chronic interstitial nephritis of many years standing. Has had several attacks of chronic uremia with tendency to muscular weakness on left side. The case, which has been under continuous observation for a period of five years, shows the most consistently high systolic pressure ever encountered by the author.

At the last observation, both symptomatically and by physical examination, the patient appears to be in a generally better condition than in 1910. The urine still shows increased volume, reduced specific gravity, occasional granular and hyaline casts and traces of albumin.

a case showing less arterial involvement and a lower pressure accompanied by a poor myocardium. Therefore it is important in every case (see Fig. 60), not only at the first examination but during the subsequent course, to follow closely the muscular efficiency of the heart in relation to the handicap under which it is operating.

(d) Arterial Involvement.-We have seen that arterial involvement, as demonstrated by the examination of superficial vessels, is not always a safe criterion upon which to judge the degree of renal change. Arterial involvement may be very irregular in its distribution and we are not justified in condemning the kidneys upon the evidence offered by a study of the superficial branches of the arterial tree. It is also recognized that marked superficial involvement may occur without marked elevation of blood-pressure; at the same time we do not believe that a blood-pressure persistently of 200 or more can exist without some degree of general arterial and renal involvement.

(e) Blood-pressure. It has just been stated that the majority of observers now hold that a systolic pressure of over 170 is gravely suspicious, that a systolic pressure of persistently 200 or more is almost conclusive evidence of kidney involvement (see Fig. 60). This, together with a continuously increased pulse pressure, may be accepted as evidence of renal involvement per se, while the higher the systolic pressure and the longer the duration of the high pressure the more likely is this to be true.

(f) Renal Functional Efficiency. However attractive it may appear, from the scientific point of view, to estimate the degree to which the anatomic elements of the kidney are involved, it would seem that the mixed type of nephritis, so frequently encountered clinically, practically disposes of any attempt to arrive at fine diagnostic distinctions concerning the reactions secured by differential function tests. Even in the simplest clinical type of nephritis there is enough general structural alteration to render conclusions as to special functional involvement hazardous.

Therefore as the matter stands, the only methods available for clinical usage are such as furnish information as to the total function of the kidneys, i.e., their excretory capacity.

The original deductions of Roundtree and Geraghty, which have been fully corroborated by subsequent obververs, show that the amount of phthalein excreted varies, as a general rule, with the extent of renal damage. The test is also valuable in cardiorenal cases with failing heart and kidney engorgement. Such a condition is accompanied by a low phthalein output, which rapidly rises as the heart's action improves, so that this change in such a case may be the earliest sign of restoration of compensation, when it becomes of considerable prognostic importance. On the other hand, a persistently low excretory capacity with apparent clinical evidence of cardiac improvement points to a severe nephritis and to a less favorable prognosis.

Efforts to explain the relation of the phthalein test, as seen in practice, to the anatomic conditions revealed in the kidney in necropsy have been made by many, including Thayer and Snowden.1 Their cases show that in severe chronic nephritis there occurs most uniformly an unusually low phthalein output, which as a rule, unless interrupted by an acute terminal process, decreases steadily up to the onset of uremia, and that excretion may be nearly or wholly suppressed for from only a day or two to a month before death. These authors state that not in all their studies for five years have they met with a good phthalein excretion in a case of chronic nephritis.

There seems to be no question as to the usefulness of this

1 Am. Jour. Med. Sci., 1914, cxviii, 781.

test, which when periodically employed constitutes a method of value in nephritic and high-pressure states generally. It has been observed that the response to the test is on an average higher in ambulatory than in hospital cases, irrespective of the clinical condition present.

It was first suggested by Miller and Cabot and has been more or less confirmed since, that the excretion of the phthalein grows progressively less with advancing years, irrespective of the kidney condition.

It is a common experience to note that the output is well within the requirements in the majority of cases grouped as nephritis, when accompanied by good cardiac compensation, so that while these observations therefore may not be of great value in diagnosis, they are of undoubted service in the study of nephritis, where they may often furnish the much-needed clue to the presence of doubtful and unsuspected uremic conditions. The phthalein test is also of value in separating the cardiorenal from the cardiovascular cases. Finally from the prognostic standpoint the test offers us great assistance when employed periodically.

The general consensus of opinion now bears out the original conclusions of Folin, Dennis and Seymour regarding this test in relation to the nonprotein nitrogen of the blood, namely, that cumulative phenomena occur only when excretion of phthalein falls below 40 per cent. in the first two hours.

(g) Eye-ground Examination.-Ocular symptoms are often among the very earliest signs which are susceptible of detection by careful examination, although in some cases these changes may be greatly delayed. This fact