IV. THE URINE IN DISEASE

In this section the characteristics of the urine in those diseases which produce distinctive urinary changes will be briefly reviewed.

1. Renal Hyperemia.—Active hyperemia is usually an early stage of acute nephritis, but may occur independently as a result of temporary irritation. The urine is generally decreased in quantity, highly colored, and strongly acid. Albumin is always present—usually in traces only, but sometimes in considerable amount for a day or two. The sediment contains a few hyaline and finely granular casts and an occasional red blood-cell. In very severe hyperemia the urine approaches that of acute nephritis.

FIG. 60.—Sediment from acute hemorrhagic nephritis: Red blood-corpuscles; leukocytes; renal cells not fattily degenerated; epithelial and blood-casts (Jakob).
FIG. 61.—Sediment from chronic parenchymatous nephritis: hyaline (with cells attached), waxy, brown granular, fatty, and epithelial casts; fattily degenerated renal cells; and a few white and red blood-corpuscles (Jakob).

Passive hyperemia occurs most commonly in diseases of the heart and liver and in pregnancy. The quantity of urine is somewhat low and the color high, except in pregnancy. Albumin is present in small amount only. The sediment contains a very few hyaline or finely granular casts. In pregnancy the amount of albumin should be carefully watched, as any considerable quantity, and especially a rapid increase, strongly suggests approaching eclampsia.

2. Nephritis.—The various degenerative and inflammatory conditions grouped under the name of nephritis have certain features in common. The urine in all cases contains albumin and tube-casts, and in all well-marked cases shows a decrease of normal solids, especially of urea and the chlorids. The characteristics of the different forms are well shown in the table on opposite page, modified from Hill.

THE URINE IN NEPHRITIS
PHYSICAL. CHEMIC. MICROSCOPIC.
Acute nephritis. Quantity diminished, often very greatly. Color dark; may be red or smoky. Specific gravity, 1.020 to 1.030. Urea and chlorids low. Much albumin: up to 1.5 per cent. Reaction acid. Sediment abundant, red or brown. Many casts, chiefly granular, blood and epithelial varieties. Red blood-cells abundant. Numerous renal epithelial cells and leukocytes.
Chronic parenchymatous nephritis. Quantity usually diminished. Color variable, often pale and hazy. Specific gravity, 1.010 to 1.020. Urea and chlorids low. Largest amounts of albumin: up to 3 per cent. Reaction acid. Sediment rather abundant. Many casts of all varieties: fatty casts and casts of degenerated epithelium most characteristic. Blood present in traces: abundant only in acute exacerbations. Numerous fattily degenerated renal epithelial cells, often free globules of fat, and a few leukocytes.
Chronic interstitial nephritis. Quantity markedly increased, especially at night. Color pale, clear. Specific gravity, 1.005 to 1.015. Urea and chlorids low in well-marked cases. Albumin present in traces (often overlooked), increasing in late stages. Reaction acid. Sediment very slight. Few narrow hyaline and finely granular casts. No blood except in acute exacerbations. Very few renal cells. Uric acid and calcium-oxalate crystals common.
Amyloid degeneration of kidney. Quantity moderately increased. Color pale, clear. Specific gravity, 1.012 to 1.018. Slight decrease of urea and chlorids. Variable amounts of albumin and globulin. Sediment slight. Moderate number of hyaline, finely granular, and sometimes waxy casts.