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Hydrogen Ion Activity in Serum (pH)

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

This test measures the acidity or alkalinity of your blood serum, which is crucial for maintaining normal bodily functions.

Quick summary

["Your blood’s pH helps balance your body’s chemistry and supports vital processes like enzyme function and nutrient absorption."]

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

Key facts at a glance

LOINC
73238-8
Short code
Nizatidine ind plt IgM SerPl Ql FC
Synonyms
Nizatidine ind plt IgM SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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, expressed on a scale from 0 to 14. A pH of 7 is neutral; below 7 is acidic, above 7 is basic. Blood normally stays slightly alkaline, around 7.35–7.45, to prevent harmful effects from excess acidity.

Why Is pH Important?

Blood pH affects how well your body’s proteins, enzymes, and cells function. Too much acidity (acidosis) or alkalinity (alkalosis) can lead to fatigue, confusion, or even organ damage. This test helps doctors diagnose conditions like diabetes, kidney disease, or respiratory issues.

When Might You Need This Test?

Your doctor may order a pH test if you have symptoms like unusual tiredness, shortness of breath, nausea, or muscle weakness. It’s also checked during monitoring for chronic illnesses like kidney disease, heart conditions, or metabolic disorders.

What to Expect Before the Test

No special preparation is needed for this blood test. A healthcare provider will draw blood from a vein in your arm. The process is quick and usually painless, though you might feel a slight pinch. If you’re on blood thinners, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum pH

Frequently asked questions

How Does pH Affect Your Health?
Abnormal pH levels can signal serious underlying issues. For example, low pH (acidosis) might indicate diabetes, kidney problems, or excessive vomiting, while high pH (alkalosis) could point to overuse of antacids, severe dehydration, or respiratory problems. Regular monitoring helps manage conditions like chronic obstructive pulmonary disease (COPD) or heart failure.
What Happens If My pH Is Out of Range?
If your pH is too low or too high, your doctor may recommend lifestyle changes (like diet adjustments or hydration) or treatments to restore balance, such as medications or breathing therapies. Follow-up tests will help track improvements.
Does Diet Affect pH Test Results?
Yes, certain foods and drinks can temporarily alter blood pH. Avoid excessive caffeine, alcohol, or acidic foods (like citrus) 24 hours before the test. Your doctor may also advise fasting if the test is part of a metabolic 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