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Blood test for fatigue

Blood test for persistent fatigue

Fatigue rarely has a single cause. A comprehensive blood test surfaces the biological factors, from iron deficiency and thyroid function to vitamin D and inflammation, so you know where to start.

Book your blood test
01 Scope
0+
biomarkers per test
02 Reach
0+
draw locations in the Netherlands
03 Access
No
referral needed
01 Causes

Which blood values reveal what is behind fatigue?

For persistent fatigue, doctors usually look at the same set of markers: iron status (ferritin, serum iron, transferrin), vitamin B12 and folate, vitamin D, thyroid function (TSH, free T4), blood sugar (HbA1c, glucose) and inflammation (CRP). Each of these can cause fatigue on its own, sometimes it is a combination.

Optimize measures them all at once. No separate test requests, no multiple visits: one draw, one report.

02 Picture

One measurement, broad picture

Instead of chasing tests symptomatically, you get the full picture. The app shows what is optimal per value, which combinations are typical with fatigue and where the most likely starting points are.

Example: low ferritin with normal Hb points to iron deficiency that can play out for years before it leads to anaemia. High TSH with low T4 points to hypothyroidism. Both are classic fatigue causes that can be missed on a narrow test.

03 Next

What do you do with the results?

Per marker, the app gives context: what is normal, what is optimal and where you stand. For mild deviations, lifestyle adjustments can shift the trend.

For significantly off values, especially in combinations that may point to a condition, we recommend talking to your doctor. Optimize does not diagnose or treat.

Understand where your fatigue is coming from. Start with a comprehensive blood test.

Book your blood test

The biomarkers that matter for fatigue

The five areas where the cause of persistent fatigue is most often found, and which we measure in one blood test:

Iron status & anaemia
8 biomarkers
  • Ferritin
  • Serum iron
  • Transferrin
  • Transferrin saturation
  • Hemoglobin
  • Hematocrit
  • MCV
  • RDW
Thyroid
2 biomarkers
  • TSH
  • Free T4 (only if TSH is abnormal)
Vitamins
5 biomarkers
  • Vitamin D
  • Vitamin B12
  • Folate (vitamin B11)
  • Homocysteine
  • MMA
Blood sugar
2 biomarkers
  • Hemoglobin A1c
  • Glucose (fasting)
Inflammation
2 biomarkers
  • C-reactive protein (CRP)
  • Total white blood cells
Beyond the baseline
Follow-ups & add-ons

Beyond the baseline there are deep-dive tests and add-ons for specific questions.

Browse all biomarkers

Clarity on where your energy is leaking

One test covers iron, thyroid, vitamins, blood sugar and inflammation
See where the first wins are, before ordering individual tests
Track whether your values move with your adjustments
FerritinSerum ironTransferrinTransferrin saturationHemoglobinHematocritMCVRDWTSHFree T4Vitamin B12FolateVitamin DMethylmalonic acidHomocysteineGlucoseHemoglobin A1cC-reactive proteinLeukocytesLymphocytesMagnesiumCalciumSodiumPotassiumALTASTCreatinineeGFRFerritinSerum ironTransferrinTransferrin saturationHemoglobinHematocritMCVRDWTSHFree T4Vitamin B12FolateVitamin DMethylmalonic acidHomocysteineGlucoseHemoglobin A1cC-reactive proteinLeukocytesLymphocytesMagnesiumCalciumSodiumPotassiumALTASTCreatinineeGFRFerritinSerum ironTransferrinTransferrin saturationHemoglobinHematocritMCVRDWTSHFree T4Vitamin B12FolateVitamin DMethylmalonic acidHomocysteineGlucoseHemoglobin A1cC-reactive proteinLeukocytesLymphocytesMagnesiumCalciumSodiumPotassiumALTASTCreatinineeGFR
eGFRCreatinineASTALTPotassiumSodiumCalciumMagnesiumLymphocytesLeukocytesC-reactive proteinHemoglobin A1cGlucoseHomocysteineMethylmalonic acidVitamin DFolateVitamin B12Free T4TSHRDWMCVHematocritHemoglobinTransferrin saturationTransferrinSerum ironFerritineGFRCreatinineASTALTPotassiumSodiumCalciumMagnesiumLymphocytesLeukocytesC-reactive proteinHemoglobin A1cGlucoseHomocysteineMethylmalonic acidVitamin DFolateVitamin B12Free T4TSHRDWMCVHematocritHemoglobinTransferrin saturationTransferrinSerum ironFerritineGFRCreatinineASTALTPotassiumSodiumCalciumMagnesiumLymphocytesLeukocytesC-reactive proteinHemoglobin A1cGlucoseHomocysteineMethylmalonic acidVitamin DFolateVitamin B12Free T4TSHRDWMCVHematocritHemoglobinTransferrin saturationTransferrinSerum ironFerritin

How to investigate fatigue via your blood

01 Download
Download the app
Create a free Optimize account.
02 Pick
Pick a broad panel
Choose the Baseline or a fatigue-focused panel with the markers that matter for energy.
03 Draw
Book a blood draw
Book an appointment at one of the 238+ locations. Fasting is recommended for blood sugar.
04 Understand
See where the cause is
Get clear explanations per area (iron, thyroid, vitamins, blood sugar, inflammation) in the app.
05 Track
Re-test on target
Working on a specific deficiency (e.g. vitamin D, ferritin)? Re-test after 8 to 12 weeks to see the change.
FAQ

Frequently asked questions

The key questions on blood testing for fatigue.

Which blood values matter for fatigue?

Ferritin and iron status, vitamin B12 and folate, vitamin D, thyroid values (TSH and free T4), blood sugar (HbA1c and glucose) and inflammation marker CRP. Optimize measures them all in one blood test.

What is ferritin and why does it matter?
Can vitamin B12 deficiency cause fatigue?
When should I see a doctor?
Do I need a referral for this test?

Understand your fatigue, start with the numbers.

A broad blood test points to where the first wins are.