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Baseexcessstdbldmvcalcscnc

Published: August 9, 2026Updated: August 16, 2026

This test measures the base excess in mixed venous blood, helping doctors evaluate your body's acid-base balance and tissue oxygenation status.

Quick summary

{"Base excess measures the amount of excess acid or base in your blood","Mixed venous blood comes from veins returning blood from all body tissues","Helps doctors diagnose and monitor conditions affecting blood pH balance","Commonly used in critical care and cardiac surgery settings","Normal values typically range from -2 to +2 mEq/L"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
19238-5
Short code
Base excess std BldMV Calc-sCnc
Synonyms
Base excess std BldMV Calc-sCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
calculated
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

The base excess test measures the amount of base (alkaline substances) in your mixed venous blood. Mixed venous blood is blood that has traveled through all the tissues in your body and is returning to the heart. This test is calculated from other blood gas measurements rather than directly measured.

Why is it important?

Base excess is a key indicator of your body's metabolic acid-base status. A positive base excess means your blood is too alkaline (basic), while a negative value indicates your blood is too acidic. This information helps doctors understand how well your body is oxygenating tissues and maintaining proper pH balance, which is essential for normal cell function.

How is the sample collected?

A healthcare provider will draw a blood sample from a vein, typically using a syringe designed for blood gas analysis. The sample is usually taken from a central venous catheter or a pulmonary artery catheter in hospitalized patients. The sample must be analyzed quickly to ensure accurate results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is this test painful?
The blood draw may cause brief discomfort similar to a standard blood test. If you have a central venous catheter, the sample may be drawn through it without additional needle sticks.
How long does it take to get results?
Results are typically available within minutes to a few hours since the sample needs to be analyzed quickly using specialized blood gas equipment.
What do abnormal results mean?
A negative base excess (metabolic acidosis) may indicate conditions like kidney failure, diabetic ketoacidosis, or severe infection. A positive value (metabolic alkalosis) may be seen in vomiting, diuretic use, or certain kidney disorders. Your doctor will interpret results in context with other tests.
Do I need to fast before this test?
Fasting is typically not required since this test is usually performed on hospitalized patients. Your healthcare team will provide specific instructions if needed.
Can I request this test myself?
This test is ordered by healthcare providers and is performed in hospital or clinical laboratory settings. It is not typically available as a routine outpatient test.
  1. 1
    MedlinePlus - Blood GasesSource
  2. 2
    American Association for Clinical Chemistry - Base ExcessSource
  3. 3
    May Clinic - Acid-base balanceSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy