A Cream For Two Sun Spots Changed My Bloodwork

Hey Reader, Dr Karl here.

Two of my numbers moved the wrong way this year.

IGF-1 dropped 30 points — from 142 to 115. Fasting insulin rose from 3.6 to 4.5.

Neither is alarming on its own. Together, moving in opposite directions in the same year, they’re a question. So I went looking for what changed.

About a month before the draw I’d seen my dermatologist — routine, I go every year. Fair skin, northern European ancestry, I collect sun spots. Actinic keratoses. He gave me a cream and told me to use it for two weeks. I used it for a few days.

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The cream is fluorouracil. It is the same drug oncologists run through a chemotherapy IV bag for their cancer patients. It’s one of the most widely used cytotoxic drugs in the world. In a tube. For my face. And on the 5% formulation, it’s measurably absorbed: in one pharmacokinetic study, fluorouracil was detectable in the plasma of nine out of ten patients using it.
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Clearly it goes way beyond the face.

Now the honest part, because I won’t overstate this: I cannot prove from a single blood draw that the cream moved my IGF-1. What I can tell you is the timing fit, the drug’s mechanism fits, this has been documented in others as well.
​This is the entire point ​
 I only knew to ask the question because I’ve tracked these numbers year over year and read them against each other.

A one-time panel would have shown me nothing but “in range.”

Your labs remember exposures you forget. But only if someone is watching them.

To be clear: actinic keratoses are pre-cancerous and treating them is good medicine. My dermatologist did the right thing.

The lesson isn’t fear — it’s know what you’re being handed, and do your labs before and after if in doubt.

The full story, with my numbers on screen:

https://www.youtube.com/watch?v=b1B8QJyx0GE​
To your health,
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Dr. Goldkamp

That’s the whole reason I wrote Unlocking Optimal Metabolic Health: A Data-Driven Approach to Thriving at Any Age — to show you how to read your own labs, see the patterns, and act on real data instead of generic reference ranges.

📗 Grab the book Here: website​​

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