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I've been having low T symptoms so I had my level checked. Came back 542 ng/dL. I then learned about Free T and bioavailability so I had my level checked again and this time included Free T. The results came back: Total: 550 ng/dL Free: 48.7 pg/mL (46-224) Bioavailable: 91.7 mg/dL (110-575) Albumin 4.1 g/dL SHBG 55 nmol/L (22-77) Estradiol 29 pg/mL (<=39) Prolactin 10.1 Do I understand correctly that a high SHBG binds the testosterone making less free and bioavailable? In my case the SHBG is normal with a normal testosterone but borderline low free and bioavailable. I see people posting and talking about their total testosterone levels but rarely seeing but he discuss their free and by available levels. Do you treat with normal total but low free and buy available? Can you give me some guidance regarding mine? I think the levels I have done for the free and by available are calculated so next week I'm having them checked again with the lab using Mass Spectrometry/Equilibrium Dialysis.

AlphaMD's Answer

Free T is the only “active” T. That means it is the only T available to attach to androgen receptors. Bioavailable T is a combination of free T and T attached to albumin (albumin easily releases T to allow it to become free T).When SHBG binds T, it never releases it. Ever. So T attached to SHBG doesn’t get to attach to the androgen receptors, essentially making it inert.

If someone has low total T, then they don’t have much reserve, and will almost always drop into symptomatic free T ranges throughout a 24 hour cycle.Someone with normal T can have low free T due to high SHBG +/- high albumin.“Low T” is diagnosed with either a low TT or a low FT.

You meet criteria for low T based on your symptoms combined with borderline low FT. If those levels were drawn in the morning, your levels will drop by 15% or more throughout the day. This means that by the afternoon your FT is likely around 40 or below.You meet criteria for treatment.

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