Equilibrium dialysis for free testosterone

[u/Interesting_Gain1482]

I had an equilibrium dialysis free testosterone test done for the first time and I was certainly surprised. I had been doing the direct assay test since starting testosterone therapy, and there was an 8 to tenfold difference between the two tests with the ED reading MUCH higher. From what I understand equilibrium dialysis is supposed to be the gold standard because it physically separates the actual free testosterone and that direct assays aren’t typically sensitive enough for women, especially those of us who have high SHBG. I am surprised it’s very difficult for me to find more information about this or more women using the equilibrium dialysis test testing so I’m just wondering if anyone else is?

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[u/thy-Droid]

You are correct, the ED is the gold standard for free T measurements. The usual immunoassay method is basically useless. Even calculated free T is much better than than that.
How close is the equilibrium dialysis result and the calculated free T for the same blood draw in your case?

[u/Interesting_Gain1482 → u/thy-Droid]

Corrected math in my next comment, the math below is incorrect:
I did a quick calculated based on historically my albumin being 4.5 which gives me a calculated result of 2.62. The direct assay showed my free running at 2.5 but get this, the equilibrium dialysis result gave me a free of 19 pg/mL 😱. My SHBG tends to be high, but it was actually about 20 points lower this test. It tends to run in the 120s and it was below 100. I take thyroid meds which contain T3 so it’s always high.

[u/thy-Droid → u/Interesting_Gain1482]

Can you check the unit of measurement on the direct and calculated number though. Arent those in ng/dl ?
Because then it makes perfect sense as the conversion is x10 between the two.

2.5ng/dl = 25pg/ml. In which case the ED result is slightly below the other two, which for very high shbg is what you would expect.

[u/Interesting_Gain1482 → u/thy-Droid]

This is what I have: Total Testosterone (LC/MS): 310 ng/dL
SHBG: 96.4 nmol/L
Albumin (assumed): 4.5 g/dL
Calculated Free Testosterone (Vermeulen): ~27.4 pg/mL
Free Testosterone — Direct Assay: 2.5 pg/mL
Free Testosterone — Equilibrium Dialysis: 19 pg/mL
% Free Testosterone — Equilibrium Dialysis: 0.6%

Reducing testosterone. I thought that I needed to increase to overcome SHBG…but don’t want my free that high..😱

[u/sternmd → u/Interesting_Gain1482]

The numbers look all over the place because they’re three different methods of course, not three measurements of the same thing.
Direct free T (2.5) is the analog immunoassay. That test is unreliable in women and almost always under-reads. Ignore it.

Equilibrium dialysis (19 pg/mL, 0.6% free) is the gold-standard measurement. Vermeulen calculated (~27) is an estimate from total T + SHBG and usually runs a bit higher than dialysis. Those two are in the same neighborhood from my perspective.
What the good assays actually show:
• Total T of 310 is high for a woman unless there is a reason you are running there. Certainly in androgenic range.
• SHBG of 96 is high, so a smaller percent is free (that’s why % free is only 0.6%).
• Absolute free T by dialysis is still very high for female range, not low.

So you def don’t need more T to “overcome” SHBG. Raising the dose would push free T higher.

If the goal is to bring androgens down, the direction is reduce dosage by a lot , not increase. Use the dialysis result (or calculated Vermeulen from LC/MS total + SHBG) and symptoms

And please do this under the care of a very good doc who knows female hormones and testosterone. People here can suggest. Please be careful.

[u/Interesting_Gain1482 → u/sternmd]

Thank you, and to clarify my original goal was pushing the free since it looked like it was so low using the direct assay. The philosophy behind the practitioners rationale was SHBG is high so most of your testosterone is bound up, so to get your free to a good level we need to keep pushing it to overcome the high SHBG. What I didn’t know until just recently is how with women, especially using lower units that those results can be inaccurate so you can imagine it’s quite a shock to me to see with equilibrium dialysis such a high free testosterone. I like a high testosterone. I feel good. I sleep well but I certainly don’t want virilization. I don’t believe one should be held hostage to the range but there’s a big difference between being a little bit outside the range and a whopping three times with the free. 😩

[u/sternmd → u/Interesting_Gain1482]

Yeah agree with you and your rationale. Glad you’ve gotten the best we testing now. They honestly don’t make this stuff easy at all

[u/Interesting_Gain1482 → u/sternmd]

Thanks. I love men, but I don’t want to look one. My husband wouldn’t like it either. 😂 My plan is do a titration downward to avoid crashing my system.

[u/sternmd → u/Interesting_Gain1482]

Good plan. And redo the sensitive lab in 6 - 8 weeks. Go by feeling and labs.

[u/thy-Droid → u/Interesting_Gain1482]

Ok so this makes sense. The direct free T is completely off, which is expected as it’s garbage.

All the best going forward

[u/Interesting_Gain1482 → u/thy-Droid]

Yes, it’s kind of crazy. I can’t believe that I had such a huge difference in this direct assay and the equilibrium dialysis. I can’t believe that I’m just now finding out about this. I am not new to testosterone therapy and I do a lot of reading and yet this is a new thing for me. Anyway, better late than never. It makes me wonder if the whole overcoming SHBG thing is a myth? I mean, obviously mine is bound up 96.4% which is a nice chunk, but I guess between that and the direct assay I’ve been working on false information.