Is eGFR worth drawing at baseline before starting dulaglutide?

For reference: eGFR · dulaglutide.

This is a planning question. I know what my options are; I do not know how to weigh them.

What I want is the minimum viable version, which I suspect is smaller than what I would design.

How do I make this decision on evidence rather than on feel?

Start with a baseline. A result taken before anything started converts most later ambiguity into a simple comparison, and it cannot be obtained retrospectively.

A twenty-analyte panel run on a healthy person will produce, on average, one out-of-range result purely from how reference intervals are constructed. That is arithmetic rather than pathology.

Specifically, delta checks — comparing against your own previous value — are far more sensitive than comparing against a population interval, which is the argument for keeping a series rather than a snapshot.

Research-use compounds are not approved for human use, and no panel makes that safer.

Decide the action for each result before you order the test.

edited 6 Jul 2026 by fiadh_cronin — clarified the distinction between purity and content

The relevant statistical point is that a ninety-five per cent reference interval means one analyte in twenty will read out of range in a healthy person by construction.

Same laboratory, same method, same time of day, same fasting state. Between-laboratory differences on several common analytes are larger than the changes people are trying to detect.

Timing matters per analyte: cortisol and testosterone are diurnal, triglycerides are postprandial, and creatinine responds to hydration and to recent training. Fixing the conditions removes most of the noise.

Biological variation data are published per analyte and are the basis for the reference change value — the difference between two results that is larger than noise.

Keep the full report, not the number. You will need the units and the interval later.

This is answerable, and the answer is mostly about which tests rather than how many.

Repeat before you react. A single abnormal value has a substantial probability of being within the combined biological and analytical variation of a normal one.

The caveat is that a panel is not a diagnosis and interpreting one is a clinician's job, particularly when several values move together.

One out-of-range value on a twenty-analyte panel is expected. Two on a repeat is a finding.

The short version: a small, well-chosen panel with a baseline beats a large one without.

Haemolysis in the sample raises potassium and several enzymes spuriously. If a result is bizarre, ask whether the sample was flagged before building a theory on it.

External quality assurance schemes document between-laboratory differences on common analytes that routinely exceed the size of clinically interesting changes.

Nothing here is medical advice. If something is out of range and you do not know why, that is a consultation rather than a research project.

Baseline first, then a repeat under identical conditions. Everything else is secondary.