THE URINE IN THE FIRST DAYS OF LIFE The secretion of urine (hiring the first day of life amounts to only a few cubic centimetres: sometimes none is voided. On the second and third days, still very little urine is voided, hut here the amount is dis tinctly dependent Ott the ingestion of fluid. From now on the amount secreted depends mostly on the amount of fluid taken, so that GO to 70 c.c. urine are secreted for each 100 c.c. milk taken. Accordingly, the amount of urine secreted in 21 hours may be calculated as 200 c.c. on the fourth clay, and as 300 c.c. on the seventh day. The frequency of urination varies greatly, and may amount to 20 or 25 times in 21 hours. Corresponding to the small quantity, the concentration and the nitrogen content of the urine are relatively great in the beginning. The specific gravity varies between 1.008 and 1.012: it diminishes rapidly to 1.003 to 1.004, to remain for months at this level. The color of the urine is intensely yellow in the first days, and the reaction is acid: even the freshly voided urine is somewhat turbid, owing to the precipitation of urates and epithelial cells the urinary passages. In the second half of the first week the urine becomes clear and its color a light yellow, corresponding to the low concentration.
The chemical examination shows in numerous newborn infants (in all, according to Flensburg) the presence of albumin (nucleoproteid). Toward the end of the first week, in the majority of cases, this surpris ing phenomenon ceases, but sometimes a trace of albumin may be found for weeks. The morphological elements to be found are epithelial cells from the urinary passages, leucocytes, amorphous or crystalline uric acid. hyaline, granular, and epithelial casts, brown masses of ammonium orate in the shape of casts, and occasionally epithelial cells from the kidneys. While the number of casts becomes very small on the third day and these soon disappear completely, leucoeytes, epithelial cells from the urinary passages, and large quantities of urates are still found to the end of the first week.
A complete agreement of opinion in regard to the causes and the meaning, of this albuminuria or the newborn has not been reached. but it seems probable that it is not due to any morbid process in the mother or the child, but is a physiological phenomenon. The changes in the culation, in the quality of the blood, and in the metabolism from bryonic to extra-uterine life may be regarded as the foremost causes. Closely connected with this are the uric acid infarcts in the kidneys., of the newborn, first described by Virchow. In the great majority of infants dying on the second or third day, a large number of yellowish red stria. are to he Seim microscopically in the pyramids, starting from the middle or occasionally from the border of the medullary substance, and converging like the straight urinary tubules toward the papilla. Alicroscopically, the straight uriniferous tubules are filled with cylin druid pieces of yellowish brown and partly gray color or with granular masses. They are composed of ammonium orate or crystals of uric acid, imbedded in a hyaline-like, partly unformed, portly cylindroid substance. after careful investigations, explains the origin
of the uric acid infarct as follows (cited from Czerny and Keller, D Kindes Er r zing , etc., part I, p. Time primary part of the infarct is formed by the proteid-like substance, which is secreted in the convo luted tubules of the kidney luring embryonic life. When during the first days of life the kidneys secrete it very concentrated urine rich in unites, the hyalin-like elements of the infarct block its way and prevent its passage. The almost insoluble ammonium unites, present in large quantities, are deposited on this byalin-like substance like salts crystal lizing from a concentrated solution on a string.'' Flensburg and Hens sing explain the increase in the excretion of uric acid during the first week by the supposed hyperleucocytosis of the first days of life. A large number of leucocytes perish, and furnish the material for the in creased production of uric acid. according, to the well known investiga tions of ITorbaczewski. Although it is not certain that the concentra tion of the urine and its content of uric acid in the first days of life constitute the only causes of the uric acid infarct, it may be per missible to assume that the infarct is not due to a morbid process. but represents more or less a physiological phenomenon. This assumption is strengthened by the fact that the kidneys frequently do not show any pathological changes, in spite of the presence of an infarct.
From the foregoing it will be readily understood that the formation of a uric acid infarct is rarely to be found in still-born infants or in in fants dying a few hours after birth. and this fact has frequently been made use of in forensic medicine. Most frequently the infarct is observed in infants dying in the second half of the first day or on the second or third day: it is seen much less frequently on the fourth and fifth day. and from then on only very exceptionally. Taken as a whole, a uric acid infarct is found in more than half of the infants between two and fourteen days of age, on which a post-mortem is performed (Hecker).
The fact that the albuminuria occurs at the time \viten the uric acid infarct is observed, points to a connection between these two mani festations. Virchow, and particularly Hofineier, called attention to this connection. It is probable that as a rule the mechanical or chemical irritation caused by the infarct gives rise to the albuminuria, and the appearance of casts, etc., might easily be dependent on the same causes. But sometimes the course of these two processes shows certain differences.
For instance, the infarct is seen in only a small number of cases during the second week of life, while albumin is still excreted though in dimin ished quantities. Therefore, as Flensburg justly remarks, the presence of the infarct is not sufficient to explain the occurrence of the albumin uria. Further investigations are needed to decide this question finally.