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Hydrogen Ion Concentration (pH) in Serum

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

This test measures the acidity or alkalinity of your blood by checking the concentration of hydrogen ions, which determines your pH level.

Quick summary

["Your blood pH helps balance your body’s acid-base balance, crucial for health and function."]

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

Key facts at a glance

LOINC
33114-0
Short code
GA from HC.Lessoway98
Synonyms
GA from HC.Lessoway98
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-hc-lessoway
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

What Does pH Measure?

pH is a measure of how acidic or basic (alkaline) your blood is. It’s measured on a scale from 0 to 14, where 7 is neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity. Blood must stay close to pH 7.35–7.45 to function properly.

Why Is pH Important?

Maintaining proper pH is essential for many bodily processes, including enzyme function, nerve signaling, and red blood cell health. Too much acidity or alkalinity can lead to health problems like fatigue, muscle cramps, or even life-threatening conditions.

Common Causes of Abnormal pH

Changes in pH can result from conditions like diabetes (high blood sugar can lower pH), kidney disease (which affects acid excretion), or respiratory issues (like asthma or lung infections that alter CO₂ levels). Certain medications, diet, and dehydration may also influence it.

What Does a pH Test Tell Your Doctor?

Your doctor may order a pH test to diagnose or monitor conditions like metabolic acidosis or alkalosis, acid reflux, or kidney function. It can also help guide treatment for chronic illnesses or after surgery.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum pH

Frequently asked questions

What triggers a pH blood test?
A pH test may be ordered if you have symptoms like persistent nausea, unusual fatigue, muscle weakness, confusion, or frequent urination. Doctors may also check pH as part of a broader evaluation for chronic conditions like diabetes, kidney disease, or metabolic disorders.
How is the pH test performed?
A blood sample is taken from a vein in your arm. The sample is sent to a lab, where it’s analyzed to measure hydrogen ion concentration. Results are usually available within 24 hours.
What are the typical reference ranges for pH?
Normal blood pH ranges from 7.35 to 7.45. Values outside this range may indicate acid-base imbalances that need medical evaluation.
  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