In a formal letter to CMS, CAP criticized Z codes. I asked "Chat GPT" to take the role of MolDx and respond.
Then, I asked for a summary in the witty style of Lewis Black.
Original: https://www.discoveriesinhealthpolicy.com/2026/03/cap-tells-cms-z-codes-are-highly.html
##
Somewhere in Washington, two perfectly serious organizations are having a polite argument that sounds like it was written by people who have never thrown a chair through a window—but who really want to.
On one side you have the College of American Pathologists, who are saying, in their calm professional way: “Look, we already have a coding system. It’s called CPT. The entire medical universe uses it. It’s transparent, regulated, and recognized by federal law. Why on earth are you making us add this extra thing called a Z-code that lives in some registry in the administrative Bermuda Triangle?”
And on the other side you have MolDx, who respond in the equally calm professional tone of someone explaining to a toddler why you can’t microwave a hamster: “Because CPT codes don’t actually tell us what the test is.”
And this is where it gets fun.
Because the whole fight boils down to a bureaucratic reality that is so deeply absurd it could only exist in American healthcare: the billing code for a molecular test often doesn’t identify the test.
Think about that for a moment.
In most parts of life, if you buy something, the label tells you what it is.
If you buy a sandwich, the label does not say “Food Product: Category 81162.”
But in molecular diagnostics, that’s basically the system.
So CMS looked at this situation and said, “Maybe we should have a way to know which test someone actually ran before we pay thousands of dollars for it.”
Which seems reasonable—until you hear the solution.
The solution is Z-codes.
Not government codes.
Not AMA codes.
Not federal standards.
No. These are alphanumeric identifiers issued through something called the DEX Registry, which sounds less like a regulatory system and more like a Pokémon database.
Somewhere in America a lab director is thinking:
“I have CPT codes from the AMA, coverage rules from CMS, billing edits from Medicare Advantage plans, and now I need a proprietary code from a contractor registry to prove what test I’m running.”
At which point the lab director pours a drink.
CAP’s complaint, translated into normal English, is basically this:
“Why are we using a secret decoder ring invented by a Medicare contractor when we already have a national coding system developed by the entire medical community?”
And MolDx replies:
“Because your national coding system doesn’t tell us what the hell you’re billing for.”
And that’s the real punchline.
Both sides are right.
CAP is absolutely correct that inventing quasi-official codes that only exist inside a contractor registry feels like the administrative equivalent of duct tape and chewing gum.
But MolDx is also correct that CPT codes for genomics are about as specific as labeling every car on Earth ‘vehicle.’
So the system we’ve created is this:
You bill with CPT codes that don’t identify the test,
and then attach Z-codes that actually identify the test,
so the payer can decide whether the CPT code you used should be paid.
If Franz Kafka had gone to medical school, this would have been his thesis.
Meanwhile the patient—the person all of this is supposedly for—is just hoping their doctor can order a test without triggering an administrative scavenger hunt involving three coding systems and a registry login.
But the real beauty of the debate is the tone.
Everyone writes letters like this:
“We respectfully submit that the current framework may introduce operational complexities…”
That is Washington-speak for:
“This system is insane.”
And somewhere in the middle of all this, a Medicare administrator has to decide whether the future of genomic medicine is going to be governed by the official national coding system, or a contractor registry full of Z-codes.
Which raises the most important question of all:
If CPT codes don’t identify the test,
and Z-codes identify the test but aren’t official codes…
what exactly are we coding?
Because from the outside, it looks less like a reimbursement system and more like a very expensive episode of Who’s on First?
Only instead of Abbott and Costello, it’s CMS, CAP, MolDx, and about twelve million laboratory claims.
And the punchline is the same every time.
The claim gets denied.
