The Test That Wasn't Done

Every year or so, a consultancy publishes the size of Mexico’s in-vitro diagnostics market. The number lands in inboxes, slides into investor decks, gets cited in strategy meetings. Billions of dollars, a respectable growth rate, a clean breakdown by segment — chemistry, immunoassay, haematology, molecular. It is a useful number. It is also the wrong one.

The market sizing measures what was billed. It does not measure what was needed. The distance between those two figures — the tests that guidelines recommend, that the clinical situation demanded, that the platform was built to run, and that never got ordered — is one of the most consequential numbers in this sector. No market sizing report captures it, because nobody can bill for it.

What the report counts, and what it misses

A market sizing exercise starts from the supply side. It surveys manufacturers and distributors, aggregates reagent and instrument sales, and extrapolates. The output is a defensible estimate of revenue. But revenue is a photograph of what flowed through the system. It says nothing about what the system could have done, and chose not to.

Consider a private laboratory with a fully automated immunoassay platform. The menu includes tumour markers, reproductive hormones, cardiac biomarkers, thyroid panels. The instrument is capable. The reagents are in stock. The technicians are trained. Now consider what actually gets ordered.

An oncologist follows a breast cancer patient with metastatic disease. The guideline calls for serial CA 15-3 monitoring to assess treatment response. The physician orders it — sometimes. When insurance pushes back, when the cost of the panel competes with the cost of the consultation, when the laboratory’s commercial team has never explained why serial monitoring matters, the test slips. The platform was ready. The test was on the menu. The guideline was clear. The test was not done.

Multiply that across every analyte, every specialty, every laboratory in the country. The aggregate is not a rounding error. It is a structural feature of the market — and it is invisible to any report that starts from the invoice.

Three mechanisms that create the gap

The first is economic. NAAT — the molecular method for chlamydia and gonorrhoea — is more sensitive than culture-based methods (CDC, 2021). But it costs more, and in a laboratory whose pricing structure is built for volume in routine chemistry, the molecular test sits on the menu at a price point that discourages adoption. The physician knows NAAT is the better diagnostic. The patient would benefit. The test is not ordered, because the price signal is misaligned with the clinical value. The market report counts the cheaper method that was billed and misses the one that should have been.

The second is contractual. The comodato — the instrument placed in exchange for a reagent commitment — determines which assays are economically viable on a given platform. If a laboratory’s main analyser sits under a contract that makes a specific marker expensive to run relative to its reimbursement, that marker is economically unviable on that platform for the duration of the contract. The platform has the capability. The test is registered. The reagent is available. But the economics of the installed base suppress it. This is not a technology gap. It is a commercial-structure gap, and it does not appear in any TAM calculation.

The third is informational. A laboratory can offer a test that its referring physicians do not know to ask for. Vitamin D is a case in point: widely available on automated platforms, clinically relevant across several populations, and yet ordered far less than its prevalence data would justify. Not because physicians doubt its utility, but because the laboratory has not invested in the clinical communication that would make ordering it a habit. The test is on the menu. The physician has never been told why it matters for their patient population. The test is not done.

The unaddressed market in Mexican IVD is not a region on a map. It is the space between what the platform can do and what the system actually asks it to do.

Why this matters for strategy

A laboratory director who reads the market report and sees growth has no reason to question the number. But if the growth is coming from the same routine chemistry that everyone already runs, while the markers that would differentiate the laboratory clinically sit unused, the strategy is built on a comfortable fiction. The laboratory is growing in revenue and shrinking in clinical relevance.

The laboratories that will matter in five years are not the ones chasing share in the billed market. They are the ones measuring their own gap — the delta between installed capability and actual utilisation — and closing it. That requires a different dashboard. Not reagent revenue by month, but test utilisation by clinical indication. Not volume per analyser, but the percentage of eligible patients who received the test the guideline recommended.

This is harder to measure. It requires the laboratory to think like a clinical institution, not a service business. It means understanding which physicians order which tests, for which patients, and why — and then building the communication and education infrastructure that closes the gap between capability and practice.

The patient behind the number

There is a reason this matters beyond strategy. Every test that was not done was a clinical decision made with incomplete information. A fertility patient whose AMH was not ordered because the panel was priced for routine hormones. A cardiology patient whose NT-proBNP was not run for heart failure monitoring because the immunoassay it required sat under a comodato whose reagent pricing made the test unviable at the laboratory’s price point. A sexual health workup where NAAT was available but a less sensitive method was billed — cheaper to run, and less informative for detecting active infection.

The market report will never capture these. They are the negative space of the industry — the tests that exist in capability but not in practice. And the patients who needed them are the reason the gap is not an analytical curiosity but a clinical failing.

Market sizing is not wrong. It is incomplete in the direction that matters most. It tells you what the market did. It does not tell you what the market failed to do. And in a sector where every result touches a life, the unmeasured gap is not a strategic oversight — it is the quiet cost of a system that counts its revenue but not its omissions.

The curve that matters is not the one that rises on the growth chart. It is the one that dips between what was possible and what was done. Reading that gap honestly is where the next chapter of this market begins.