
Phlebotomy Exam Prep 59, Diurnal Variation Drug and Hormone Tests
Published: June 25, 2026
Duration: 3:18
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- Cortisol levels peak around 8 AM and are lowest in the evening, a critical timing factor for diagnosing endocrine disorders like Cushing's or Addison's disease.
- Other common tests like ACTH, TSH, and iron also exhibit significant diurnal variation, making morning collections the standard for accurate interpretation.
- Therapeutic drug monitoring requires p...