In short
- Most dizziness comes from the balance organ or blood pressure regulation, not from the blood.
- A blood test mainly adds something with a persistent light or floaty feeling without a spinning character.
- The blood count, blood sugar, sodium and potassium, vitamin B12 and TSH are then the most useful values.
- With loss of strength, speech problems or blackouts, do not wait for a result but seek help straight away.
Three kinds of dizziness, three directions
Doctors broadly distinguish vertigo, light-headedness and unsteadiness when standing or walking. Where the cause usually lies differs per form:
| Form | How it feels | Most common direction |
|---|---|---|
| Vertigo | the surroundings seem to move | balance organ, such as loose crystals or an inflamed balance nerve |
| Light-headedness | floaty, often when standing up | blood pressure regulation |
| Unsteadiness | wobbly when standing or walking | nerves and balance, sometimes a vitamin B12 deficiency |
For these forms a blood test is rarely the first step: your GP usually recognises them from your story and a brief examination. Migraine, hyperventilation, anxiety and a blocked ear can also cause dizziness; the moment, the duration and the triggers of the complaints often say more than any single test.
When is a blood test actually worthwhile?
A blood test adds the most with a persistent light or floaty feeling without a clear spinning character, certainly in combination with tiredness, paleness, thirst, tingling or medication use such as diuretics. The blood can then confirm or rule out a number of causes:
- anaemia
- disturbed blood sugar
- disturbed salts
- a vitamin B12 deficiency
- abnormal thyroid function
Five directions, one blood draw.
Include your medication list in that consideration. Diuretics, blood pressure medication, antidepressants and diabetes medication can all cause dizziness or affect the salts and blood sugar.
If you have recently started a medicine or the dose has changed, discuss it with your GP or pharmacist. Also mention your medication use when having blood drawn, so the reviewing doctor can place the result in the right context.
Anaemia: haemoglobin and the blood count
With anaemia the blood carries less oxygen. You notice that first during exertion and when standing up: light-headed, more quickly out of breath, tired, sometimes palpitations and pale skin.
A blood count measures haemoglobin and the most important blood cells in one go. The result not only shows whether there is anaemia, but often also gives a first clue to the cause, for instance towards iron deficiency or a vitamin shortage.
At Bloodworks you can have the Blood Count package tested for €49, plus a €29 collection fee (free above €225). One tube of blood, reviewed by a doctor, with the results typically within 2 working days as a clear PDF report. If the blood count points to anaemia, the logical next step is to look into the cause together with a doctor; anaemia is a finding, not a final diagnosis.
Blood sugar: too low and too high
A dip in blood sugar can cause a light-headed, shaky and sweaty feeling, especially in people using diabetes medication. Persistently raised blood sugar shows itself more subtly: thirst, urinating more often, tiredness and sometimes light-headedness.
Fasting glucose (€49 all-in) shows the snapshot; HbA1c (€59 all-in) summarises the average of the past two to three months. If you are unsure, fasting glucose is the accessible first step; a doctor can then indicate whether HbA1c adds anything.
Electrolytes: sodium and potassium
Salts such as sodium and potassium keep the fluid balance and nerve signalling in order. Low sodium occurs mainly in older people, with the use of diuretics and with drinking very large amounts of water, and can show itself in dizziness, confusion and falls. Abnormal potassium can affect the heart rhythm.
These tests are most worthwhile with medication use, or after a period of vomiting, diarrhoea or heavy sweating. Sodium and potassium each cost €49 as an individual test; the Electrolytes package (€89) measures the most important salts in one go. If you mainly drink water without eating on hot days or during long training sessions, sodium can drop temporarily; that too is a well-known pattern behind light-headedness.
Vitamin B12 and the thyroid
Vitamin B12 is needed for healthy nerves. A long-standing deficiency can cause unsteadiness when walking, often together with tingling or numbness in the feet or hands, and it is precisely that combination with dizziness that is quite often missed.
The thyroid influences heart rate and blood pressure: both an overactive and an underactive thyroid can cause a light-headed or restless feeling. TSH is the first measurement for that. If you have been living with these kinds of vague complaints for a while, one combined draw prevents you from hopping from single test to single test for months.
Have vitamin B12 measured at Bloodworks
Vitamin B12 as an individual test, including doctor interpretation and a personal PDF report. No referral required, results typically within 2 working days.
Back to basics, honestly: by far most dizziness does not come from the blood. If you get short spinning attacks when turning over in bed or tilting your head back, there is a good chance it is caused by crystals in the inner ear.
Your GP can test for this and often treat it straight away with a simple manoeuvre. A blood test adds little in that scenario. Even so, ruling things out is not wasted effort: knowing where the problem is not is often the fastest route to the right treatment.
Frequently asked questions
Can a blood test show the cause of dizziness?
Sometimes, for instance with anaemia or disturbed sodium. More often the value of a blood test lies in ruling these causes out, so you and your doctor can search further in a more targeted way. The balance organ itself cannot be measured in blood.
Which blood values are most worthwhile with dizziness?
Haemoglobin and the blood count, fasting glucose, sodium and potassium, vitamin B12 and TSH. Which come first depends on your complaints and your medication use. Always discuss an abnormal result with a doctor before drawing your own conclusions.
Do I need to fast for these tests?
Only for fasting glucose. When you order, you receive instructions per test, so you know exactly where you stand.
When should I not test, but see a doctor straight away?
With sudden dizziness together with double vision, speech problems, loss of strength or a drooping mouth, call 112 immediately. With blackouts, palpitations, chest pain or dizziness after a fall, contact your GP the same day.
Do I need a referral?
No. You have blood drawn without a referral at one of over 750 affiliated collection points across the Netherlands. Every result is reviewed by a doctor.
If you are wondering whether your dizziness has a measurable cause, that does not have to remain a question for weeks. A single blood draw maps the most common blood-related causes, with a personal doctor interpretation and a clear PDF report.
And if the report points to something, it also tells you what a logical next step is. Use the result for what it is meant for: as a starting point for a good conversation with a doctor, not as a final diagnosis.