I have run across an interesting case that is similar to only two others I've encountered. What makes it interesting is the combination of undetectable (under normal testing conditions, can elaborate here if needed) of cholesterol, both LDL and HDL, and elevated testosterone in a human male with no signs or detectable testicular cancer. The reported diet is quite high in cholesterol and fat, and the person seams otherwise healthy (seen as healthy screen).
Before I decide how worthy this is to follow up on, I was wondering if anyone has, or could put together, a fairly exhaustive list of all the down stream uses for cholesterol or closely related sterols.
If we start at intake, I assume that a large portion of consumed lipopoteins/cholesterol just pass through the bowls. A portion of it will be absorbed, which might be considered meal-derived cholesterol. Humans will certainly take up a lot of the animal fat consumed, which is going to lead to what I believe is the majority of serum cholesterol, especially over time.
So we already have one way cholesterol is expended: waste. Other notable pathways that I'm aware of:
- Creation of cell walls, vesicles membranes, membrane proteins, and tissue membranes
- Storage (in the liver, adipocytes, or elsewhere)
- Production of bile
- Production of sterones
- Circulation in blood or interstitial fluid for the purpose of direct singling *[would love a reference for the levels/amounts that this happens]
- Production of lipid rafts
- Absorbed by the gut flora
- Vitamin D
- Component of breast milk
Please feel free to expand on any of these in the list already, but I'm also looking for what I haven't considered or thought of. Another way to think of this question is "where are all the places a cholesterol molecule might go in the body?"
While I'm looking mostly at humans, I would gladly accept answers from mammalian animal models as the pathways at these lower levels are likely conserved (unless you can tell me why they wouldn't be).