A markedly alkaline urine pH may be caused by which artifact?

A markedly alkaline urine pH may be caused by which artifact?

• A. Dehydration
• B. Improperly preserved specimen
• C. Cold storage
• D. Room temperature

Answer: (B)

The main idea here is that preanalytical factors can alter urine pH. If a urine specimen isn’t properly preserved, bacteria in the sample can multiply and produce ammonia by breaking down urea. This ammonia raises the pH, making the urine appear markedly alkaline. It’s an artifact because the change comes from how the sample was handled, not from the patient’s true physiology. Dehydration tends to concentrate the urine but doesn’t typically cause a strong alkalinization. Cold storage slows bacterial growth and helps preserve the original pH. Room temperature can allow bacterial growth, but the specific issue described is improper preservation, which directly leads to the alkaline shift.

The main idea here is that preanalytical factors can alter urine pH. If a urine specimen isn’t properly preserved, bacteria in the sample can multiply and produce ammonia by breaking down urea. This ammonia raises the pH, making the urine appear markedly alkaline. It’s an artifact because the change comes from how the sample was handled, not from the patient’s true physiology.

Dehydration tends to concentrate the urine but doesn’t typically cause a strong alkalinization. Cold storage slows bacterial growth and helps preserve the original pH. Room temperature can allow bacterial growth, but the specific issue described is improper preservation, which directly leads to the alkaline shift.