Skip to main content
Your session has expired. Reloading...
Minerals

Bicarbonate (HCO3-): from prolonged vomiting to Cushing's syndrome

According to MedlinePlus, bicarbonate (HCO3-) is the form in which most carbon dioxide is in the body, and it is an electrolyte: an electrically charged mineral that helps control the amount of fluid and the balance between acid and base.

According to MedlinePlus, too much CO2 in the blood can be a sign of Cushing's syndrome, and too little of Addison disease. Only a blood test gives the bicarbonate level in mmol/L.

Certe uses 24 - 28 mmol/L for bicarbonate, with the Tietz textbook as its source.

Doctor's Assessment Included

According to the NVKC, bicarbonate (HCO3-) is the main form of carbon dioxide in the body. The kidneys can excrete it or hold on to it to keep the balance between acid and base.

  • Star-SHL uses 20 - 31 mmol/l for bicarbonate, Unilabs 22.0 - 29.0 mmol/l, Certe 24 - 28 mmol/L and Diagnostiek voor U 21 - 28 mmol/L.
  • According to the NVKC, a raised bicarbonate together with a high pH fits a metabolic alkalosis, with prolonged vomiting among the possible causes.
  • According to the NVKC, a lowered bicarbonate together with a low pH fits a metabolic acidosis, with diabetes and serious kidney problems among the possible causes.

Bicarbonate: what Dutch laboratories use

There is no nationally agreed reference value; this is what individual laboratories publish.

The upper limit runs from 28 mmol/l at Certe to 31 mmol/l at Star-shl.

Reference ranges by group, in mmol/l
Star-shl · Everyone 20–31 mmol/l
20 31
Unilabs · Everyone 22–29 mmol/l
22 29
Certe · Everyone 24–28 mmol/L
24 28
Diagnostiek voor U · Everyone 21–28 mmol/L
21 28
0 34.1 mmol/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

Bicarbonate: what this test measures

A bicarbonate test gives the amount of HCO3- in the blood in millimoles per litre (mmol/L), and for the related total CO2 test the NVKC also gives the names TCO2 and alkali reserve.

Bicarbonate: why this value matters

Bicarbonate matters because, according to the NVKC, HCO3- together with sodium, potassium and chloride is important for electroneutrality at cell level, the balance between positive and negative charge.

Bicarbonate: how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test
Complete Metabolic Panel · €149,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

Bicarbonate: when is testing worthwhile?

According to the NVKC, checking whether possible side effects of medicines disturb the acid-base balance is a reason to measure total CO2, with bicarbonate as its main form.

Bicarbonate: symptoms of a high or low value

Low Levels

A bicarbonate below Certe's 24 mmol/L fits too little CO2 in the blood, which according to MedlinePlus may be a sign of, among other things, Addison disease or shock.

High Levels

A bicarbonate above Certe's 28 mmol/L fits too much CO2 in the blood, which according to MedlinePlus can be a sign of, among other things, Cushing's syndrome.

Bicarbonate: causes of a low or high value

What lowers the value

  • Diabetic ketoacidosis

    Too little CO2 in the blood may be a sign of diabetic ketoacidosis, a complication of type 1 and type 2 diabetes.

  • Serious kidney problems

    Serious kidney problems can be a cause of a metabolic acidosis: a low pH together with a lowered HCO3- in the blood.

  • Long-lasting diarrhoea

    Long-lasting diarrhoea is one of the possible causes of a metabolic acidosis, in which there can be too little CO2 in the blood.

  • Hyperventilation

    Too little CO2 in the blood may be a sign of a respiratory alkalosis, which comes from a lung or breathing problem, including hyperventilation: rapid, deep breathing.

  • A tube opened before analysis

    After the collection tube is opened, the bicarbonate concentration falls by about 6 mmol/L per hour; the tube must stay closed until analysis.

What raises the value

  • Prolonged vomiting

    Prolonged vomiting, with loss of acid from the stomach, can cause a metabolic alkalosis: a high pH together with a raised HCO3- in the blood.

  • An overdose of bicarbonate

    An overdose of bicarbonate can be a cause of a metabolic alkalosis with a raised HCO3-.

  • Cushing's syndrome

    Too much CO2 in the blood can be a sign of Cushing's syndrome.

  • Lung diseases

    Too much CO2 in the blood can be a sign of lung diseases.

Bicarbonate: lifestyle and this value

With an abnormal bicarbonate, also tell your GP whether you have recently been vomiting for a long time, because the NVKC names that as a possible cause of a raised HCO3-.

Bicarbonate: frequently asked questions

Can prolonged vomiting raise bicarbonate?

Yes, according to the NVKC prolonged vomiting can cause a metabolic alkalosis through loss of acid from the stomach, with a raised HCO3- in the blood.

Bicarbonate: sources

  1. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  2. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  4. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  5. MedlinePlus, Carbon Dioxide (CO2) in Blood, medlineplus.gov, geraadpleegd 2026-10-19 (retrieved 2026) medlineplus.gov
  6. NVKC, Alles over testen: Bloedgassen, allesovertesten.nl, geraadpleegd 2026-10-19 (retrieved 2026) allesovertesten.nl

See Lunarahealth more often in Google

Add us as a preferred source. Google will then show our articles more often in your search results and in AI overviews. You can turn this off again at any time.

That did not work. Please try again.

Test Products

This marker is included in the following test panels.

Metabolism

Complete Metabolic Panel

Comprehensive metabolic panel: electrolytes, kidney, liver, glucose, HbA1c, and protein.

HbA1c (Glycated Hemoglobin) ALT (Alanine Aminotransferase) Calcium ALP (Alkaline Phosphatase) AST (Aspartate Aminotransferase) Bilirubin (Total) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Glucose (Fasting) Bicarbonate Chloride Sodium Potassium Albumin Total Protein Bilirubin (Direct) Bilirubin (Indirect)
€149,-

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
Welzijn en Sport Official BIG registration BIG 49928676701 Opens in a new tab

Bicarbonate

€10,-