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Serum or Plasma pH (Quantitative)

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

This test measures the acidity or alkalinity of your blood (pH) by analyzing a sample drawn from your vein. Blood pH helps doctors assess whether your body is maintaining proper balance between acids and bases.

Quick summary

["Blood pH levels can signal acid-base imbalances that may require medical attention."]

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

Key facts at a glance

LOINC
41488-8
Short code
Cryptosp Spec Ql Acid fast Stn
Synonyms
Cryptosp Spec Ql Acid fast Stn
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
acid-fast-stain
CPT
84484
SNOMED
302774002
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order a blood pH test to diagnose or monitor conditions affecting acid-base balance, such as kidney disease, metabolic disorders, or severe dehydration. It can also help evaluate symptoms like fatigue, confusion, or unusual breathing patterns that may indicate an imbalance.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for a few hours before the draw if your doctor specifies it. Wear comfortable clothing and arrive with an ID if you have any allergies or medical conditions.

During the Test

A healthcare provider will insert a small needle into a vein in your arm to draw blood. You may feel a brief pinch, but the procedure usually takes just a few minutes. The blood sample is then sent to a lab for analysis.

What the Results Mean

Blood pH results are typically reported as a numeric value between 7.35 and 7.45 in healthy adults. Values outside this range may indicate acidemia (too acidic) or alkalemia (too alkaline), which can signal underlying health concerns.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

pH Level in Blood

Frequently asked questions

What causes blood pH to change?
Blood pH can shift due to factors like severe dehydration, kidney problems, breathing disorders (e.g., COPD), or metabolic conditions (e.g., diabetes). Stress, certain medications, or even overuse of acidic foods/drinks may also play a role.
How long does it take to get results?
Results are usually available within 1–2 business days, depending on lab processing times. Your doctor will discuss findings during your follow-up visit.
Can I eat or drink before this test?
Standard fasting rules may apply, but always follow your doctor’s instructions. If fasting isn’t required, avoid caffeine or alcohol before the draw to ensure accurate results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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