Why Bloodwork Comes Before Peptide Therapy

I'll start with the part of my job I find hardest. Telling a patient who's spent weeks researching peptides, comparing providers, and finally landed on a clinic that "gets it" that their bloodwork shows we shouldn't be starting therapy.

Sometimes it's a thyroid result that's been untested for years. Sometimes it's iron stores so low that nothing a peptide does would matter until we fix that first. Sometimes it's a metabolic marker that points to a different intervention being more appropriate than the one they came in asking about. Whatever it is, that conversation only happens because we ordered the labs.

There's a model of telehealth in Australia right now where this conversation never happens. The patient picks the peptide. A provider, sometimes a doctor they'll never meet, signs the script within minutes. There are no bloods, no thorough workup, no real follow-up plan. The patient gets what they clicked on, fast and without much consideration.

I want to explain why I won't practise that way, and why you should be cautious of any provider or telehealth company who does.

What bloodwork actually tells us

Bloodwork gives us a snapshot of what is happening in your body the moment it is drawn, and a glimpse into the weeks leading up to that moment. It can be divided into three things.

It tells us if there's something we'd be making worse. Plenty of conditions that should change a prescribing decision don’t show up as symptoms until things are in a pretty bad position. Subclinical hypothyroidism doesn't announce itself. Early kidney dysfunction doesn't either. Iron overload, abnormal liver function, undiagnosed insulin resistance with normal fasting glucose… all of these can be sitting in a patient who feels fine, and all of them change how we should think about peptide therapy. You can't see them without testing for them.

It gives us a baseline to measure against. This one matters more than people realise. If I start a patient who needs peptide therapy on treatment without considering their baseline numbers, I have no way to tell you in three months whether it's working. "Feeling better" is useful information, but it's not enough. We know how convincing the placebo effect can be, too. Therapy that produces real physiological change should produce changes I can show you on paper. Without baseline labs, I'm guessing, and you're paying me to guess; and, ultimately it can lead to developing conditions that could make you worse off.

It lets me see the trajectory. A single set of bloods at six months tells you where you are. A baseline plus a follow-up tells you what changed and how fast. For most peptide protocols this is the difference between titrating properly and adjusting blindly. Practicising good medicine includes having a plan, and an end goal.

"I feel fine" doesn't mean what you think it means

I see this almost every week. A patient comes in for a consultation. They're fit, they sleep well, they eat well, they have the energy to be running their own business or training six days a week. They tell me they feel great. They want a peptide they’ve read about because they want to feel even better.

Then we run the labs.

Sometimes everything's optimal. But sometimes, something unpredictable shows up. An Apolipoprotein B level sitting in cardiovascular-risk territory. A cholesterol level creeping toward increased risk of heart disease. Low iron that explains a fatigue pattern they'd written off as “part of being a parent.”

None of these patients felt unwell. The body is good at compensating, and young to middle-aged adults are particularly good at it. The point at which dysfunction becomes symptomatic is well past the point at which it becomes clinically meaningful. By the time you feel something, the underlying issue has often been there for years.

This is why I'm wary of any model of care that uses subjective wellbeing as a proxy for objective health status. They're not the same thing. And peptides aren’t always the answer here. In fact, peptides should really only be considered after proper investigations and other interventions like diet, exercise, physio have been implemented.

What I order, and why

The exact panel depends on what we're considering, but for any patient interested in peptide therapy, I'd typically want to see:

• A full blood count and iron studies, to rule out anaemia or iron overload before we change anything else.
• A comprehensive metabolic panel: analysing kidney function, liver enzymes, electrolytes, fasting glucose. These have to be within acceptable ranges before considering any pharmacological intervention.
• HbA1c and fasting insulin. Insulin will often shift before glucose does, and a lot of peptide-relevant decisions hinge on metabolic health.
• A lipid panel, with consideration of testing apolipoprotein B for patients above 35 or with serious risk factors. Standard cholesterol panels miss things that ApoB catches.
• A hormonal panel if relevant to the therapy. Total testosterone, free testosterone, SHBG, oestradiol, LH, FSH, prolactin. And for metabolic interventions, a full thyroid panel which is more in depth than a regular thyroid screening test.
• High-sensitivity CRP for inflammation. Sometimes ferritin too, which doubles as an inflammatory marker when elevated.
• Vitamin D, B12, folate. Sometimes magnesium and zinc.
• PSA in male patients above the relevant age threshold.

That's not a small panel. It's one based on years of medical research and education. Each test is on the list because it changes a decision I might otherwise make wrong.

The interpretation matters more than the panel

Running labs is the easy part. Interpreting them properly is where most of the clinical work happens.

A reference range on a pathology report tells you the central 95% of the population. It doesn't tell you what's optimal. A free T3 in the lower 5% of "normal" is technically unflagged but can be clinically meaningful in a patient with the symptoms that match. A ferritin of 30 ng/mL is "normal" but most clinicians I respect would call it suboptimal for many functional purposes.

The other thing that matters is reading the panel as a system rather than as a list of individual numbers. Elevated SHBG with low free testosterone, in a patient whose total testosterone looks normal-ish, tells a different story than the same total testosterone with low SHBG. Mildly elevated liver enzymes alongside high GGT and high ferritin point one direction; the same enzymes with normal GGT and normal ferritin point another. None of this analysis is possible if the prescribing decision happens before the bloodwork.

What I won't do, and why other providers do

I won't prescribe peptide therapy in a first consultation without ordering bloods first. There's no clinical justification for it that I find convincing. The patient hasn't been hurt by waiting four to six weeks for a proper workup. The patient may well have been hurt by skipping it.

The reason some providers in Australia do prescribe without bloodwork is straightforward: it's faster, cheaper to deliver, and easier to scale. A consultation that ends with "let's get some labs and reconvene in a month" doesn't convert to a script today. A consultation that ends with a script today does. The economics push providers toward speed, and the regulatory boundary between "telehealth efficiency" and "clinical corner-cutting" doesn't always get strictly enforced.

I understand the patient appeal. People are busy. People want results. But the speed they're being offered isn't actually saving them anything. It's just transferring risk from the provider's decision-making process to the patient's body, which is a transfer most patients wouldn't agree to if they understood it that way.

A practical checklist for any peptide provider

Whether you end up working with us, with one of our competitors, or with a GP who's never prescribed a peptide before, there are questions worth asking.

1. Will they prescribe without baseline bloodwork? If yes, walk away. There's no version of good practice that includes this.
2. What pathology do they order, and can they explain why each test matters for your specific situation? A clinician who can't tell you why they're ordering a test shouldn't be ordering it.
3. Is there a follow-up protocol with repeat testing? Therapy without monitoring is therapy without feedback. Repeat bloods at three to six months are the minimum.
4. Is the prescriber AHPRA-registered, and can you find them on the public register? Every legally prescribing medical practitioner in Australia is searchable. If a provider hides the prescribing clinician's identity behind a brand, that's worth pursuing.
5. Do they communicate uncertainty? Anyone who tells you peptide therapy is right for everyone, has no contraindications, and produces predictable results across patient populations is misrepresenting the evidence.
6. What happens if the labs suggest peptides aren't the right intervention for you right now? A clinically rigorous provider will sometimes recommend against the therapy you came in asking for. A provider whose business model depends on prescribing rarely delivers that conversation.

The point

Peptide therapy can do useful things. The evidence base for some peptides is strong, for others it's developing, and the regulatory landscape will keep evolving. None of that justifies skipping the diagnostic step that should come first.

If you walk into a consultation with me, I'm going to want to see your bloodwork before I write anything. If your bloodwork's already current, great, we'll work from that. If it isn't, we'll order it. The four to six weeks that takes is not a delay you'll regret.

The question to bring to any provider, including this one, is simple: what does my bloodwork show, and what does it tell us about whether this therapy is right for me right now?

If they can't answer that, they shouldn't be prescribing.

— Dr Taylor Kline Chief Medical Officer, Halo