Understanding a Total Testosterone of 357 ng/dL
A total testosterone level of 357 ng/dL falls in the borderline-low range, sitting just above the traditional cutoff of 300 ng/dL but below the optimal range, and requires measurement of free testosterone to determine if true hypogonadism exists—especially if you have symptoms like decreased libido or erectile dysfunction. 1
What This Number Means
Your total testosterone of 357 ng/dL is technically within the lower end of the normal reference range (300-800 ng/dL in most laboratories), but this doesn't tell the complete story. 1
The normal range itself varies dramatically between laboratories—the lower cutoff ranges from 130 to 450 ng/dL across different labs (a 350% difference), making interpretation challenging. 2
For younger men (20-44 years), age-specific cutoffs are higher than the traditional 300 ng/dL threshold. If you're in your 20s, the lower limit of normal is approximately 409-413 ng/dL; in your 30s, it's 350-359 ng/dL; and in your early 40s, it's around 350 ng/dL. 3
Normal testosterone levels in healthy men range from 300-1000 ng/dL, so your value of 357 ng/dL places you in the lower quartile. 4
Why Free Testosterone Matters More Than You Think
Free testosterone measurement is essential when total testosterone is borderline-low, particularly in men with obesity. The total testosterone alone doesn't distinguish between true hypogonadism and low sex hormone-binding globulin (SHBG). 1
In obesity, low total testosterone is frequently due to decreased SHBG rather than true testosterone deficiency—these men often have normal free testosterone levels despite low total testosterone. 1
A subset of men will have frankly low free testosterone levels, which occurs due to increased conversion of testosterone to estradiol in fat tissue, causing negative feedback that suppresses pituitary hormone production. 1
Free testosterone by equilibrium dialysis is the gold standard test and should be measured alongside SHBG when evaluating borderline total testosterone. 1
Critical Next Steps
Obtain a repeat morning total testosterone level between 8 AM and 10 AM to account for diurnal variation and confirm the initial result. 1, 5
Measure free testosterone by equilibrium dialysis and SHBG on the same morning sample. 1
If both total and free testosterone are confirmed low on repeat testing, measure luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to distinguish primary testicular failure from secondary pituitary-hypothalamic dysfunction. 1
Do Your Symptoms Actually Correlate?
Decreased libido is the most specific symptom associated with low testosterone and warrants further evaluation. 6, 7
Erectile dysfunction, particularly when phosphodiesterase-5 inhibitors have failed, is a reliable indicator requiring testosterone assessment. 6
Nonspecific symptoms like fatigue, depression, decreased energy, or mild cognitive changes do NOT correlate with testosterone levels and should not drive treatment decisions. 1, 6, 7
In a study of nearly 3,000 men, fatigue, depression, and erectile dysfunction were not associated with testosterone levels (p>0.6), while only decreased libido showed correlation. 7
Even in men with near-normal testosterone (250-350 ng/dL), hypogonadal symptoms did not correlate with free testosterone levels, and no discriminatory threshold could be identified. 8
Common Pitfalls to Avoid
Do not assume symptoms are testosterone-related based on a single borderline value—approximately 20% of men over 60,30% over 70, and 50% over 80 have low testosterone, but this alone doesn't warrant treatment. 1, 6
Age itself is not an indication for testing or treatment—the FDA requires testosterone products to be labeled for use only in men with low testosterone due to known medical causes, not "age-related hypogonadism." 1
Avoid testing in the afternoon or evening, as testosterone levels decline throughout the day and will give falsely low results. 5
Account for significant intra-individual variability—at least one repeat measurement should be obtained for equivocal values. 5
Treatment Considerations If Confirmed Low
The American College of Physicians recommends discussing testosterone treatment only for men with confirmed low testosterone AND sexual dysfunction who want to improve sexual function, not for energy, vitality, physical function, or cognition. 1
Treatment should be considered only when morning free testosterone by equilibrium dialysis is frankly low on at least two separate occasions. 1
Intramuscular formulations should be preferred over transdermal when initiating treatment, as costs are considerably lower and clinical effectiveness is similar. 1
Reevaluate symptoms within 12 months and discontinue testosterone if there is no improvement in sexual function. 1