Blood tests before starting a GLP-1 in Ireland
Most prescribers in Ireland will want HbA1c, kidney function, liver function and thyroid function before starting a GLP-1, often with lipids and a full blood count alongside. Expect to pay €60 to €100 privately, or nothing if you hold a medical card and your GP orders them. The tests are not a formality: they establish whether you have undiagnosed diabetes, whether your kidneys can handle the medicine, and whether something else entirely is driving your weight. Skipping them is the most common corner cut by online prescribers, and it is the one that matters most.
Why baseline bloods are not optional
There are three reasons, and only the first is about the drug itself.
The medicine needs to be safe for you specifically, which depends on kidney function and on ruling out certain conditions. Your prescriber needs a baseline, so that if something changes in six months they can tell whether it is new. And weight gain occasionally has a cause that a GLP-1 will not fix and that needs treating in its own right.
This is also the clearest dividing line between a legitimate Irish prescriber and an online service selling pens. Anyone willing to prescribe a GLP-1 from a photograph and a questionnaire, with no bloods and no follow-up, is not practising medicine.
HbA1c
A measure of average blood sugar over roughly three months, and the most important single test on the list.
It determines whether you have type 2 diabetes, prediabetes, or neither — and that changes everything downstream. The indication your prescriber writes decides which medicine is appropriate, whether the Drugs Payment Scheme or the Long Term Illness Scheme applies, and therefore whether you pay €80 a month or several hundred. A great many people discover prediabetes at this appointment.
Kidney function
Usually reported as urea, electrolytes and eGFR. It matters for two reasons.
Some GLP-1s require dose adjustment or are unsuitable in significant renal impairment. More practically, the commonest way these medicines cause kidney trouble is indirect: severe vomiting or diarrhoea during titration leads to dehydration, and dehydration puts the kidneys under strain. Knowing where you started makes that far easier to spot and manage.
Liver function
A baseline, and a check for non-alcoholic fatty liver disease, which is common in people carrying excess weight and frequently silent.
It is worth knowing about, and it is one of the things that tends to improve as weight comes down — which is a genuinely encouraging thing to be able to demonstrate at a follow-up test rather than just assert.
Thyroid function
This one occasionally changes the plan entirely.
An underactive thyroid causes weight gain, fatigue and difficulty losing weight, and it is treated with thyroid replacement rather than with a GLP-1. Finding it here saves someone months on the wrong treatment. It is not common, but it is common enough that no competent prescriber skips the test.
Separately, there is a specific contraindication worth knowing about: GLP-1 receptor agonists are contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia type 2. That is established from your history rather than from a blood test, so expect to be asked.
What might stop you starting
Most results do not. These are the ones that give a prescriber pause.
- A previous episode of pancreatitis. Generally a reason not to use this class at all.
- Significant kidney impairment. May require a different agent or a modified plan.
- Medullary thyroid carcinoma or MEN 2, personal or family. A contraindication.
- Untreated thyroid disease. Usually treat that first and reassess.
- Pregnancy, planning pregnancy, or breastfeeding. Not recommended.
- Severe gastrointestinal disease, including gastroparesis. Slowed emptying is the mechanism, which makes it a poor fit.
What it costs in Ireland
A private blood panel typically runs €60 to €100 depending on the practice and how many tests are included. Some private weight management clinics bundle it into an initial package; others charge separately, so ask before you book.
If you hold a medical card and your GP orders the tests, there is no charge. If you have private health insurance, outpatient benefit sometimes contributes, though usually only above an excess. It is worth ten minutes on the phone to your insurer before paying out of pocket.
What happens after you start
Baseline is the beginning of monitoring, not a box ticked once.
Most prescribers repeat bloods at around three to six months, and annually after that. If you have type 2 diabetes, HbA1c is usually checked at three months because that is roughly how long it takes to reflect a change. Expect weight, blood pressure and a conversation about side effects at each review as well.
If a service is not offering follow-up review at all, that tells you something about the service.
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Typically HbA1c, kidney function, liver function and thyroid function, often with lipids and a full blood count. Your prescriber decides the exact panel based on your history. Expect to pay 60 to 100 euro privately in Ireland.
Usually 60 to 100 euro privately, depending on the practice and the number of tests. There is no charge if you hold a medical card and your GP orders them. Some private clinics bundle bloods into an initial package, so ask before booking.
Some online services will prescribe without them, but no competent prescriber should. Baseline bloods establish whether you have undiagnosed diabetes, whether your kidneys can handle the medicine, and whether another condition is driving your weight.
A previous episode of pancreatitis, significant kidney impairment, a personal or family history of medullary thyroid carcinoma or MEN 2, untreated thyroid disease, pregnancy or breastfeeding, and severe gastrointestinal disease including gastroparesis.
An underactive thyroid causes weight gain and difficulty losing weight, and it is treated with thyroid replacement rather than a GLP-1. Finding it at this stage saves months on the wrong treatment. It is not common but it is worth ruling out.
Most prescribers repeat bloods at three to six months and annually thereafter. If you have type 2 diabetes, HbA1c is usually rechecked at three months, since that is roughly how long it takes to reflect a change in blood sugar.