What is the normal blood pH level?

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From the Guidelines

The normal blood pH range in humans is between 7.35 and 7.45 units. This range is critical for maintaining proper physiological functioning, as even small deviations can significantly impact enzyme activity, protein structure, and cellular processes throughout the body 1. The body maintains this precise pH through several buffer systems, primarily the bicarbonate buffer system, which consists of bicarbonate ions and carbonic acid. Some key points to consider about blood pH include:

  • Acidosis is defined as a pH < 7.35, which can be caused by respiratory or metabolic disorders 1
  • Alkalosis is defined as a pH > 7.45, which may occur with hyperventilation or certain medications
  • The respiratory system helps regulate pH by controlling carbon dioxide levels through breathing rate
  • The kidneys provide longer-term regulation by adjusting bicarbonate reabsorption and acid excretion Maintaining normal blood pH is essential for various bodily functions, including oxygen delivery to tissues, nerve conduction, and muscle contraction.

From the Research

Normal Blood pH Range

  • The normal range of pH for clinical laboratories is 7.35-7.45 2
  • The normal blood pH range is 7.36 to 7.44 3
  • Arterial pH is usually thought of as being 7.40 4

Regulation of Blood pH

  • The regulation of the intra and extracellular pH-values plays an essential role in the metabolism of the human body 3
  • Acid-base homeostasis maintains systemic arterial pH within a narrow range 2
  • The alpha-stat theory of acid-base management interprets the normal value of arterial pH as a value derived from the intracellular pH, which is close to neutrality 4

Importance of Normal Blood pH

  • Metabolic or respiratory acidosis or alkalosis, which include a deviation from the regular blood pH-range, are life-threatening conditions 3
  • Changes in pH can promote changes in vascular smooth muscle tone with impact on circulation and blood pressure control 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Effects of acid-base imbalance on vascular reactivity.

Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas, 2008

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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