Chapter 9, Problem 1SRQ

Summary Introduction

Introduction: Preanalytical or preexamination phase is considered as an important part of the total testing process. It describes the procedures that occur before an analysis. The levels of many blood components usually exhibit two types of variations or fluctuations namely diurnal variation and circadian variation.

Answer to Problem 1SRQ

Correct answer: “Peak levels of cortisol typically occur around 08:00 hours.”

Hence, the correct answer is option b.

Explanation of Solution

Reason for the correct answer:

Diurnal variation is the type of variation that happens daily. There are several factors that play an important role in this type of variation including activity, posture, eating, being awake or asleep, daylight, and darkness. The example for diurnal variation includes cortisol; its peak level normally occurs later in the morning, around 8:00 A.M.

Option b. is given as “cortisol”.

An analyte that typically occurs around 08:00 hours is cortisol.

Hence, the correct answer is option b.

Reasons for incorrect answers:

Option a. is given as “Bilirubin”.

An analyte that typically occurs around 08:00 hours is cortisol, not bilirubin. Bilirubin is a degradation product of hemoglobin.

Hence, option a. is incorrect.

Option c. is given as “Eosinophil”.

An analyte that typically occurs around 08:00 hours is cortisol, not eosinophil. Eosinophil is a blood cell.

Hence, option c. is incorrect.

Option d. is given as “Glucose”.

An analyte that typically occurs around 08:00 hours is cortisol, not glucose. Glucose is a carbohydrate molecule.

Hence, option d. is incorrect.

Hence, options a., c., and d. are incorrect.

Conclusion

The peak cortisol levels usually occur later in the morning, around 8:00 A.M.