Good GLP-1 care isn't just the prescription -- it's monitoring to ensure it's working and safe. This guide explains what bloodwork you need, when, and where to get it in the UK. If you are still choosing a provider, our private GLP-1 clinics comparison covers which clinics include monitoring in the price.
Baseline Testing (Before Starting GLP-1)
Get these tests before your first injection to establish a baseline:
| Test | Why | Normal Range |
|---|---|---|
| HbA1c | Glucose control (3-month average) | <5.7% ideal |
| Fasting glucose | Blood sugar baseline | <5.6 mmol/L ideal |
| Total cholesterol | Cardiovascular health | <5.2 mmol/L ideal |
| LDL cholesterol | "Bad" cholesterol | <2.6 mmol/L ideal |
| HDL cholesterol | "Good" cholesterol | >1.0 mmol/L ideal |
| Triglycerides | Fat in blood | <1.7 mmol/L ideal |
| Kidney function (eGFR) | Kidney health | >60 mL/min/1.73m² OK |
| Creatinine | Kidney marker | 60-110 μmol/L typical |
| Liver function (ALT, AST) | Liver health | <40 IU/L ideal |
| Albumin | Protein, nutrition | 35-50 g/L |
| Thyroid (TSH) | Thyroid function | 0.4-4.0 mIU/L |
| Calcitonin | MTC screening (optional) | <10 pg/mL |
| Vitamin B12 | Baseline before absorption changes | >200 pg/mL |
| Iron/ferritin | Baseline iron stores | Ferritin >20 ng/mL |
Get your baseline bloods first
An at-home or postal blood panel covers most of the markers above in one go, so you have a clear starting point before your first injection. A home glucose monitor is useful if you want to track fasting readings between panels.
Medichecks
Private blood testing for GLP-1 patients
AlphaBiolabs UK
Accredited health and DNA testing
Sinocare
Clinically validated glucose monitors
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Follow-Up Testing: Timeline & Schedule
3 Months (First Check-In)
Purpose: Assess early response, check safety markers
Tests:
- Fasting glucose
- HbA1c (if diabetic, or if high baseline)
- Weight & BMI
- Blood pressure
Why: Verify weight loss trajectory, ensure glucose control (if diabetic), ensure no adverse effects
6 Months (Mid-Course Assessment)
Purpose: Assess sustained progress, full metabolic panel
Tests:
- HbA1c
- Total cholesterol, LDL, HDL, triglycerides
- Kidney function (eGFR, creatinine)
- Liver function (ALT, AST, bilirubin)
- TSH
- Vitamin B12
- Weight, blood pressure
Why: Verify metabolism improving, kidney/liver safe, B12 declining (start supplementing if not already)
12 Months (Annual Assessment)
Purpose: Full reassessment before renewal
Tests:
- Full metabolic panel (as above)
- Iron/ferritin (assess hair loss risk factors)
- Weight, body composition if possible
- Blood pressure
Why: Comprehensive health picture, assess need for continued treatment
Testing Options in the UK
Option 1: Private GP / Clinic Bloodwork
Who: Your private GLP-1 clinic or private GP
Cost: Usually included in clinic cost, or £30-100 per panel
Pros:
- Integrated with your care
- Doctor reviews results
- Quick turnaround
Cons:
- More expensive than standalone testing
- Sometimes bundled (can't cherry-pick tests)
Option 2: Medichecks (Online, Home Blood Test)
Website: medichecks.com
How it works:
- Order test online
- Finger-prick blood test kit arrives
- You do test at home, post sample back
- Results in 2-3 days
- Report + interpretation online
Cost: £40-150 per panel (depending on test)
Popular panels for GLP-1 users:
- "Full Blood Count + Metabolic Screening": ~£99
- "Lipid Panel": ~£30
- "Thyroid Function": ~£35
- "Iron Panel": ~£40
- Custom panel: build your own
Pros:
- Affordable
- Convenient (home testing)
- Can order anytime
- Good interpretation
Cons:
- Results come electronically; need to interpret yourself (or email your prescriber)
- Finger-prick sometimes tricky
- 2-3 day wait
Option 3: NHS GP Bloodwork
Who: Your NHS GP
Cost: Free
How it works:
- Request appointment with GP
- Discuss GLP-1 monitoring needs
- GP orders bloodwork
- You attend local phlebotomy clinic
- Results back in 1-2 weeks
Pros:
- Free
- Integrated with NHS records
- GP reviews + advises
Cons:
- Long waits for appointments
- Limited test options (NHS usually covers basics only)
- GPS may be unfamiliar with GLP-1 monitoring
Note: Some NHS GPs will monitor GLP-1 users if you request; others won't (depends on practice).
Option 4: Private Phlebotomy Clinics
Examples: London Andrology Clinic, Nuffield Health, Spire
Cost: £100-200+ per test
Pros:
- Quick turnaround
- Arm blood draw (easier than finger prick)
- Good quality lab work
Cons:
- More expensive
- Need to visit clinic in person
- Still need to interpret or send to your doctor
Key Tests Explained: What to Look For
HbA1c (Most Important If Diabetic)
What it measures: 3-month average blood glucose
Why it matters: Shows if GLP-1 is controlling blood sugar
Target on GLP-1:
- Diabetic: <7% (some prefer <6.5%)
- Non-diabetic: <5.7% (this is "prediabetes reversal" territory)
What improves it: GLP-1 itself (directly lowers glucose) + weight loss (improves insulin sensitivity)
Lipid Panel (Total, LDL, HDL, Triglycerides)
What it measures: Cholesterol and fats in blood
Why it matters: Cardiovascular health (weight loss typically improves lipids)
Targets on GLP-1:
- Total cholesterol: <5.2 mmol/L
- LDL: <2.6 mmol/L
- HDL: >1.0 mmol/L
- Triglycerides: <1.7 mmol/L
What improves it: Weight loss (especially visceral fat loss), improved insulin sensitivity
Kidney Function (eGFR, Creatinine)
What it measures: How well kidneys filter waste
Why it matters: GLP-1 (particularly semaglutide) can slightly reduce kidney function; monitor for safety
Targets:
- eGFR: >60 mL/min/1.73m² (OK)
- eGFR 45-59: caution; monitor more frequently
- eGFR <45: discuss with prescriber (may need dose adjustment)
- Creatinine: should stay stable
Reality: Most people's kidney function stays same or improves (weight loss helps). Declines are rare and usually small.
Liver Function (ALT, AST, Bilirubin)
What it measures: Liver health
Why it matters: Rarely affected by GLP-1, but baseline check is prudent
Targets:
- ALT: <40 IU/L
- AST: <40 IU/L
- Bilirubin: <20 μmol/L
What happens: Usually improves (weight loss reduces fatty liver)
Vitamin B12
What it measures: B12 level in blood
Why it matters: GLP-1 reduces B12 absorption (slow stomach emptying); deficiency causes fatigue, neuropathy, hair loss
Targets:
-
400 pg/mL: normal, no action needed
- 300-400 pg/mL: low-normal, consider supplementing
- <300 pg/mL: deficiency, supplement or injectable
What happens: Often declines 3-6 months in; oral B12 supplementation prevents deficiency. B12 is also a key lever for preventing hair loss on GLP-1.
Action: Start oral B12 supplementation (1000-2000 mcg daily) prophylactically.
Iron / Ferritin
What it measures: Iron stores
Why it matters: Low iron worsens hair loss on GLP-1; rapid weight loss depletes iron
Targets:
- Ferritin: >30 ng/mL (below this increases hair loss risk)
- Serum iron: 12-25 μmol/L
What happens: Often declines with rapid weight loss; supplementation helps
Action: Check at baseline + 6 months; supplement if ferritin <30
When to Escalate Monitoring
More frequent testing if:
- Kidney function declining (eGFR dropping)
- Liver enzymes rising (ALT/AST elevated)
- Diabetic with poor glucose control (HbA1c not improving)
- Signs of B12 deficiency (fatigue, neuropathy symptoms)
Escalate to: Check every 3 months instead of 6 months; discuss with prescriber about need to modify GLP-1 or increase monitoring
Red Flags: When to Contact Prescriber Immediately
Results requiring urgent discussion:
- eGFR <45 (kidney function compromised)
- ALT/AST >100 (liver dysfunction)
- HbA1c rising despite GLP-1 (not responding)
- Calcitonin elevated (thyroid concern, though rare)
Realistic Cost for Full Year of Monitoring
Option 1: Private clinic included
- Cost: Usually £180-250/month (Juniper, Oviva, etc.)
- Monitoring: Included in subscription
Option 2: Budget private (Numan, Manual) + Medichecks
- Clinic: £150-180/month
- Medichecks baseline: £99
- Medichecks 3-month: £99
- Medichecks 6-month: £99
- Medichecks 12-month: £99
- Total first year: ~£2100-2400
Option 3: NHS GP + Medichecks
- NHS GP: Free (but hard to access, limited monitoring)
- Medichecks (1-2 panels/year): ~£100-200
- Total: ~£100-200/year
Key Takeaway
Minimum monitoring: Baseline tests before starting, then annually (HbA1c, lipids, kidney function, B12). Our GLP-1 supplement guide explains which deficiencies to expect and how to address them between blood panels.
Ideal monitoring: Baseline + 3-month + 6-month + 12-month panels, with B12 supplementation started prophylactically
Most cost-effective: Use Medichecks for follow-up testing; have private prescriber or NHS GP interpret
Next Steps
- GLP-1 side effects & safety guide
- B12 & supplements on GLP-1
- Thyroid & GLP-1 safety
- Private clinic comparison
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Disclaimer: This is educational information. Consult your prescriber for specific monitoring recommendations based on your health profile.