Question

The yellow color of urine is due to the presence of ___.
A. Urea
B. Uric acid
C. Urochrome
D. Bilirubin

Answer 1

Hint: Urine color is generally pale-yellow to amber. The pigment urochrome, which is a breakdown product of hemoglobin from dead RBCs, gives the yellow color to the urine.

Complete answer:
Urine color is generally pale-yellow to deep amber. The urine of a healthy person contains water, urea, inorganic salts, creatinine, ammonia, and pigmented products of blood breakdown. Hemoglobin released from dead RBCs which contain heme.

This heme converts into biliverdin and then to bilirubin. Bilirubin is then excreted as bile, bilirubin is further degraded by microbes present in the large intestine and form urobilinogen.

Some of the urobilinogen remains in the large intestine, and converts into stercobilin, which gives brown color to feces. Some urobilinogen is reabsorbed into the blood and then reaches the kidney and releases through urine. When urobilinogen is exposed to air, it is oxidized to urobilin, which is found in urine and gives yellow color to urine.

Our first option is urea. Urea is a metabolic waste of the body and it doesn't give color to urine. The next option is uric acid. The uric acid dissolve in blood and release through the kidney. It is bright orange in color. The 3rd option is urochrome. As we already mentioned, urochrome is produced from hemoglobin and gives yellow color to urine. The last option is bilirubin. Bilirubin is found in urine and it is not normally not present in the urine.

Hence, The correct answer is option (B).

Note: In a urine test we can analyse urine the amount of urobilin in urine. The amount of urobilinogen is very important for detection of urinary tract infection as the color of urine changes during urinary tract infections.