The urine should be examined daily throughout the illness for albumen. This may be found at any time from the second to the twenty-first day.
It is, however, in the course of the third week that it is especially liable to be met with.
Alburainuria does not bear any relation to severity of attack. It may be present in mild cases and absent in severe ones. By itself it does not indicate serious renal mischief, and if small in quantity does not affect the prognosis.
If the albuminuria is due to anything more than a simple congestion of the kidneys, which is of little consequence, the urine soon shows signs of the presence of nephritis. Its quantity is reduced : its colour is smoky from the presence of blood, or even deep red if the lnemorrhage is co pious ; boiling throws down a copious precipitate of albumen ; and renal epithelium, Wood-disks, and casts, granular and epithelial, are discovered by the microscope. At the same time or shortly afterwards the face is. pale or puffy-looking ; the eyelids are stiff and swollen ; and more or less oedema is noticed about the legs and ankles.
The beginning of the kidney complication is generally announced by vomiting, headache, loss of appetite, a dry skin, a pallid complexion, an ir regular pulse, and a rise in the temperature. The temperature is not very high, seldom exceeding 101°; and the vomiting is not often repeated, al though sometimes it becomes a distressing symptom. The cedema varies in amount. Sometimes it is little more than a puffiness of the skin. In other cases the swelling may be general and severe, so as completely to alter the natural expression of the face, and greatly distend the limbs and lower part of the back. At the same time effusion may take place into the se rous cavities, the lungs, and even the glottis. If these effusions are rapid and copious, great lividity and dyspncea may ensue, and death may take place with startling rapidity. The most violent attacks of dyspncea may be induced by interstitial cedema of the lungs. The patient is found gasping for breath, with a haggard, livid face. His eyes are staring and congested, his lips blue, and his nails purple. His pulse is weak and rapid and his heart's action feeble and fluttering. On examination of the chest few physical signs are to be discovered. The rhonchi are scanty and
scattered, for very little fluid, if any, exudes into the air-passages and al veoli.
In a certain proportion of cases urmmic symptoms may occur. The child is, perhaps, violently convulsed several times, and may lapse into a state of coma ; or he may be seized with headache of a very distressing character. Fortunately these symptoms usually pass off under the influ ence of judicious treatment. It is exceptional for a child to die of scarla tinous nephritis. The occurrence of the renal complication appears to be dependent in a great measure upon the character of the epidemic ; for while in some it is a common symptom, in others it is almost entirely ab sent. The popular impression that it is always the consequence of a chill has been disproved over and over again. There is no doubt that if albu minous nephritis be present, a chill may hasten the occurrence of dropsy ; but that slight exposure, such as occurs during convalescence from scarlet fever, can determine the occurrence of the nephritis is now very generally disbelieved.
In the earlier stage of the nephritis the amount of urine is diminished and its specific gravity is raised. After a time the secretion becomes more copious and at the same time its density falls. Usually the pyrexia sub sides when the quantity of urine increases. Dropsy is not an invariable symptom. It may be completely absent, although the other phenomena are well marked. As a rule the nephritis is rapidly recovered from, and the albuminuria and in-mic symptoms quickly disappear • but some times, although improvement takes place in other respects, the water still continues to throw down a deposit on boiling ; for a long time a certain amount of albumen may be present, and under the microscope the sediment may continue to exhibit casts of tubes. In exceptional cases a permanent alb miinuria may be left. In other instances, and these are probably more common than is usually supposed, the urine ceases to contain albumen and casts, and, indeed, with the exception of a low specific gravity, may pre sent all the characters of health. Still the restoration of the kidneys is not complete, and slight causes, such as a passing chill, may determine a return of all the acute symptoms which have been described.