Every letter we have printed

Fasting glucose and glycated haemoglobin can move in opposite directions over a short period and both be correct, because they describe different windows. Your table makes that visible in a way I have not seen elsewhere and I have borrowed it for teaching.

Fasting status changes several common analytes substantially, and self-arranged testing frequently records it wrongly or not at all. It is the single most common preventable source of a surprising result.

Matrix-assisted desorption deserves more space than a clause. For a large peptide it produces predominantly singly charged ions, which makes the spectrum trivial to read compared with an electrospray charge envelope, at the cost of poorer quantitation. For an identity question that trade is usually the right way round.

The in-source fragmentation point is worth a warning. Turn the cone voltage up far enough and a clean peptide will produce a spectrum full of fragments that look like impurities. The instrument is capable of manufacturing the finding it is being asked to test for, which is an argument for reporting the source conditions.

Counter-ion mass is the quiet arithmetic error in this market. A buyer weighing out a trifluoroacetate salt as though it were free peptide is short by a margin that varies with the number of basic residues. It is invisible to every method described in your series and it changes what is in the vial.

Severity grading is doing a lot of quiet work. Most reported events sit in the mild to moderate categories, and a table that reports incidence without severity puts an inconvenience and a serious event in the same column.

The most useful presentation I have seen was a cumulative curve rather than a proportion, because it showed both how many and when. It is not harder to produce and it is almost never chosen.

Delayed gastric emptying explains a good part of the early symptoms and it is also part of the intended effect, which makes the framing of these as unwanted effects slightly awkward. Your piece handles the tension well rather than pretending it is not there.

Where a trial permits a dose reduction, the reported tolerability figures describe a population that adjusted, not a population that persisted. It is a reasonable protocol and it means the headline rate is not a rate at the nominal dose.

Endoscopy has its own considerations distinct from general anaesthesia, and the two get merged in most coverage. Residual gastric contents affect the procedure itself and not only the airway question.

Where the seller ships directly to the laboratory, custody is clean and the sample is chosen. Where the buyer ships, custody is broken and the sample is representative. The trade is not acknowledged anywhere in the literature I have read.

Chain of custody is the whole game and it is the part the certificate never describes. A report on a sample the seller selected and posted is a true report about that sample. Whether that sample represents the lot is a question the laboratory is in no position to answer and does not claim to.

Your blind duplicate exercise is the most valuable thing this publication does, and eight vials is not enough to carry the conclusion you drew from it. Without replicates within each laboratory you cannot separate between-laboratory variation from vial-to-vial variation, and the honest reading is that four figures differed.

Symptoms appearing long after a stable period are a different signal from symptoms at escalation, and the timing is genuinely informative. New symptoms in a settled period deserve their own assessment rather than being attributed to the agent by default. Nothing here is medical advice.

Severe persistent abdominal pain is not a tolerability question and should never be filed as one. Your article says so clearly. I would place it earlier in the piece, because a reader who is unwell may not reach the fifth section.

Management strategies circulate in this area with very little trial support, and the honest way to present them is as reported practice rather than as evidence. Your piece does that; a great deal of adjacent coverage does not.

External calibration performed at the start of a batch will drift over a working day on some instruments. A laboratory quoting accuracy to a few parts per million on a sample run eleven hours after calibration is quoting a specification rather than a measurement, unless a lock mass was used.

A note on calibration intervals. Mass accuracy drifts with laboratory temperature, and a determination run eight hours after the last calibration is a different measurement from one run eight minutes after it. The interval is recorded in the instrument log and never in the report.

The invisible category that worries me most is the residual solvent, because it has no chromophore, ionises badly and is present by design rather than by accident. It is measured by a completely different instrument and almost never ordered.

Your anatomy of a certificate is the page I have pinned above the goods-in desk. The one field I would promote is the date of analysis as distinct from the date of issue. A certificate issued last month for a determination made two years ago is a true document about a lot that has since spent two years somewhere.

Your anatomy diagram should mark which fields are assertions by the manufacturer and which are results from an instrument. On most certificates they sit in the same table in the same typeface, and a reader has no way to tell a measurement from a claim.

Self-reported incidence collected in online communities is not comparable with trial incidence in any direction, and it is put side by side with it regularly. Different populations, different definitions, different collection, one chart.

Where the same event can be coded under two dictionary terms, incidence is split between them and each looks smaller. Coding conventions are a technical matter with a large effect on the numbers people quote.