ALBUMINURIA The almost universally accepted dictum that albumin in the urine was always a symptom of disease of the kidney, was not refuted until the celebrated investigations of von I.eube in the year IST7. Prior to this the isolated observations, which went to show that occasionally albumin might be found in the urine of otherwise healthy individuals, had utterly failed to shake the general acceptance of the relation between albuminuria and nephritis, which had first been propounded by Bright.
Von Leube has asserted that albumin was present in the urine of 4 per cent. of healthy persons examined by him, and Haat albumin in 16 per cent. was to be found when the muscles had been previously exerted, and these remarkable results have since been repeatedly confirmed and amplified by a great number of workers.
In examining the urine with the most delicate albumin reagents, the fundamental law has been established that every normal urine contains albumin, and that therefore the excretion of albumin is a physio logical phenomenon (Horner, Posner, Senator). It is true that the albumin normally excreted is in sueh infinitesimal quantities that it cannot be shown by the common albumin tests (boiling, acetic acid, ferroeyanide of potassium), and this strictly physiologieal albuminuria has no importance for the practitioner, "for w hom a latent albuminuria is of no moment, but only the excretion of albumin which responds to the usual tests, without any preparation of the urine." On the other hand if albumin can be demonstrated in otherwise untreated urine, by boiling or the addition of acetic acid, and ferrocyanide of potassium (it is always best to employ both) the result may be taken to prove the existence of abnormal conditions. The practitioner must now decide the question, hich is often difficult, hether the albumin is connected with kidney disease, or whether it is one of the forms of so-called physiological albuniinuria, sueh as may result from the upright position, tnuscular exertion, fatigue, psyehial emotion, cold baths, or diet.
Von Leube has designated all these latter forms of alburninuria as " physiological," "because, we cannot seriously speak of conditions as pathological, when in routine examination the great majority of healthy individuals show more or less albumin in the urine treated by the ordi nary tests."
It is not my intention to take part in the discussion which has resulted from this proposition, but for practical motives I have refrained from using in the following discussion the term "physiological albu minuria" in the meaning of von Leube. I understand by the term only that latent excretion of albumin which cannot be shown by ordinary tests.
The physician may meet with two varieties of albuminuria which fall within the range of physiological processes. One is the albuminuria of the newborn which appears almost always immediately after birth, and lasts for a few days; the other is the albuminuria seen in older chil dren due to the upright position, or resulting from a change from the recumbent to the erect attitude. Pavy called the latter cyclie: Stirl ing, postural: Heubner, orthotic. None of these terms has been gener ally accepted, and to reconcile the matter, Posner has proposed the name "Essential," while Neukirch suggested "Intermittent Albuminuria." To avoid repetition it will be convenient first of all to consider tbe albuminuria of childhood (including those which are the result of dis eases of the kidney) from the chemical standpoint.
The albumin appearing in the urine may come from the blood, the kidneys, the urinary tracts, or from other organs. Furthermore it may be albumin taken up directly into the vessels from the alimentary canal, i.e., nutritive albumin. Our present chemical method:3 do not permit us to separate these different forms of albumin, and to determine their exact source. But concerning the nutritive albumin we are in a slightly better position since it may be identified by the so-called pre cipitation reaction, i.e., the albumin coming from food, will be precipi tated by the blood serum of an animal hich has previously- been treated by repeated injections of this form of albumin.