When weekly bloodwork is overkill, and when it isn't

Most stable protocols don't need weekly labs. Some genuinely do. Here is how to think about the cadence of monitoring through the lens of half-life and steady state.

How often you should check bloodwork depends mostly on how stable the protocol is and how long ago the most recent change happened. There is no universally right answer, but there are several wrong ones — and "every week" and "once a year, regardless" are both usually in the wrong category. This post walks through the framework most clinical guidelines use and how the DoseCurve chart helps you visualise it.

This is educational background. Your specific monitoring schedule belongs with the clinician supervising your care.

The rule of 4–5 half-lives

The general rule is that a new protocol takes about 4–5 half-lives to reach steady state. Until then, bloodwork represents a transient state that does not reflect the long-term level you will end up at. For typical injectables:

Ester	Half-life	Time to steady state
Propionate	~0.8 days	~4 days
Enanthate	~4.5 days	~3 weeks
Cypionate	~8 days	~5–6 weeks
Undecanoate (Nebido)	~21 days	~3–4 months
Semaglutide	~7 days	~5 weeks

A blood draw before the protocol has reached steady state is genuinely informative for some things (kidney/liver function, acute safety markers) and misleading for others (testosterone level, GH-axis levels). The Endocrine Society and most other published guidelines time the first post-change measurement to fall at or after steady state for that reason.

The DoseCurve dashboard reports "time to steady state" explicitly so you can see at a glance when your modelled chart will have plateaued.

When weekly bloodwork actually helps

There are legitimate cases for high-frequency monitoring:

Acute safety concerns. A new symptom that needs to be characterised, an unexpected lab value to confirm, a suspected adverse event.
Active titration. Some short-half-life protocols with frequent dose adjustments genuinely warrant frequent monitoring while the right dose is being established.
Specific clinical scenarios. Some monitoring schedules are dictated by the medication itself (e.g. clozapine, some chemotherapy regimens). These are not optional and they are not driven by pharmacokinetic stability.
Research participation. Trials often require dense monitoring schedules for protocol reasons.

If you don't fit one of these, weekly bloodwork on a stable protocol is rarely producing actionable information. It is producing noise.

When once-a-year is too rarely

The other extreme is also a trap. Annual monitoring on a stable protocol is appropriate for some clinical scenarios and inadequate for others. Things that usually warrant more than annual checks:

Hematocrit on a TRT protocol. The published guidance is typically every 3–6 months once stable, with more frequent checks during titration.
Liver enzymes when starting any new injectable. Baseline, then at typical re-check intervals (commonly 3–6 months).
PSA on a TRT protocol. Baseline, then per the guidance your prescriber follows.
Symptom changes. Any new symptom warrants a check regardless of when the last one was.
Dose changes. A blood draw at the new steady state confirms the change landed where intended.

The right cadence depends on what's being measured and why. It is not a single number.

What the chart helps you decide

The DoseCurve chart does not tell you when to get bloodwork. It does help you decide:

When the chart has reached steady state. Until then, a draw is informative about the absorption phase but not about the long-run level.
Where in the cycle a draw will land. For a once-weekly schedule, a draw on day 3 vs day 7 sees very different mg-remaining values. Note the time-since-injection on every lab.
What a hypothetical change would do. If a clinician proposes increasing the dose by 20%, you can see the expected new steady-state shape before you make the change, and time a follow-up draw accordingly.

This is conversation-anchoring, not protocol-setting.

Recording time-since-injection

The single most useful thing you can do to make bloodwork interpretable is to record the time elapsed since your last injection at every draw. Two labs at "trough" on different schedules are not comparable. Two labs at "halfway through the cycle" on different schedules are not comparable. The labs are only interpretable in context.

A practical convention: write the time-since-injection on the lab requisition or on the patient-facing record. "Drawn 6 days, 14 hours after most recent injection" is dramatically more useful than "drawn fasting".

Common mistakes

Drawing immediately after starting a new ester. Catches the absorption phase, not steady state. Misleading.
Drawing without recording time since injection. Makes serial labs hard to compare.
Drawing at the peak when previous labs were at the trough. Apparent rise that is purely a sampling artefact.
Repeating a borderline-low result without changing technique. The same draw timing on the same schedule will give the same answer.
Skipping baseline labs. Without a pre-protocol baseline, attributing later values to the protocol is harder than it needs to be.
Treating reference ranges as universal. Labs vary in technique and population. Your lab's range is the relevant comparator, not internet consensus.

A reasonable default for a stable injectable protocol

For an established, stable injectable hormone protocol with no symptom changes:

Initial post-change draw timed at steady state (4–5 half-lives after the most recent change).
Routine safety markers per the guideline your prescriber follows (typically 3–6 month intervals for things like hematocrit, lipids, liver function).
An extra draw any time you change dose, ester, route, or schedule, again timed for the new steady state.
An extra draw any time a new symptom appears.

That is not a recommendation. It is a structure your prescriber can work from when they decide what's right for you.