Episode 155

Published May 26, 2026

In this episode, Dr. Mark Holthouse joins Dr. Jaclyn Smeaton and DUTCH founder Mark Newman to take a closer look at a recent peer-reviewed publication from Precision Analytical, Inc. in Frontiers in Reproductive Health, examining how different testing methods hold up when it comes to monitoring male TRT in clinical practice.

Their discussion also covers:

• Common misconceptions about how creams and gels show up in saliva testing and why the numbers can be misleading
• What the clinical data actually shows about dosing accuracy across different testing modalities 
• When to use serum, urine, and other testing approaches can be leveraged to optimize treatment.
• How under or overdosing risks can be reduced by matching the right test to the right clinical question
• Why advancing best practices in integrative medicine requires continually revisiting what the evidence supports

Key Moments

0:47 Episode Introduction

3:44 The Testosterone Monitoring Debate

6:35 Understanding Saliva Testing and Its Implications

13:19 Clinical Experiences with Hormone Testing

22:08 The Role of Serum Testing in Hormone Replacement

29:37 DUTCH Courses: Introduction To Menopausal HRT

30:29 Clinical Insights on Progesterone and Patient Management

34:56 Understanding Hormone Absorption and Administration

37:48 The Clinical Impact of Testosterone Dosing

42:19 Evaluating Testosterone Levels and Patient Symptoms

46:57 Navigating Testosterone Normal Ranges

53:13 The Complexity of Estrogen Monitoring

1:01:31 A Call for Evidence-Based Practices

About our speaker

Dr. Mark Holthouse, MD has practiced family and functional medicine for over three decades, specializing in men's and women's hormones, peptides, and longevity medicine. Among the first cohort to receive IFM certification in functional medicine, he has taught the men's hormone advanced module for 14 years and served as a faculty member at Loma Linda University School of Medicine, where he taught preventive cardiology. His integrative approach combines peptide therapy, lifestyle foundations, hormone optimization, and cardiometabolic health into a comprehensive longevity program. Dr. Holthouse currently sees clients full time and serves as Chief Medical Officer at the Functional Medicine Institute. Outside of his clinical role, he continues to teach and educate colleagues and patients alike. 

Show Notes

Read our DUTCH Article on the Frontiers study, Mark Newman’s commentary, and the full study here.

Check out the resources mentioned in this episode:

• The topical progesterone cream study in Fertility and Sterility
• The transdermal progesterone study from Climacteric
• Good Energy mentioned by Dr. Holthouse
• The study on the cardiovascular safety of TRT in the New England Journal of Medicine
• The study on testosterone threshold levels and skeletal muscle strength

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