Which solute is a major component of a 24-hour urine sample?

Which solute is a major component of a 24-hour urine sample?

• A. Sodium
• B. Mucus
• C. Erythrocytes
• D. Urea

Answer: (D)

Urea is the major organic solute excreted in urine over a 24-hour period. It’s produced from amino acid catabolism in the liver and then filtered into the urine by the kidneys. Because protein intake drives urea formation, and it’s the primary nitrogenous waste, it contributes the largest single portion of dissolved solutes in a daily urine sample. Sodium and other electrolytes are important inorganic solutes but don’t usually outnumber urea as a single component, while mucus and erythrocytes are not normal major urine solutes. Thus, urea best fits as the major component of a 24-hour urine sample.

Urea is the major organic solute excreted in urine over a 24-hour period. It’s produced from amino acid catabolism in the liver and then filtered into the urine by the kidneys. Because protein intake drives urea formation, and it’s the primary nitrogenous waste, it contributes the largest single portion of dissolved solutes in a daily urine sample. Sodium and other electrolytes are important inorganic solutes but don’t usually outnumber urea as a single component, while mucus and erythrocytes are not normal major urine solutes. Thus, urea best fits as the major component of a 24-hour urine sample.