Acquired pyruvate kinase deficiency

Area of Science:

• Biochemistry
• Hematology
• Enzymology

Background:

• Pyruvate kinase (PK) is essential for red blood cell glycolysis.
• Deficiency of PK leads to hemolytic anemia, both congenital and acquired.
• Accurate measurement of PK activity is crucial for diagnosis.

Purpose of the Study:

• To highlight the importance of PK in red blood cells.
• To discuss methods for measuring PK activity.
• To address challenges in diagnosing PK deficiency, especially acquired forms.

Main Methods:

• Enzyme activity assays using prepared substrates and reagents.
• Separation of red blood cells from other blood cells (e.g., granulocytes).
• Specialized techniques: low substrate concentration (PEP 0.4 mM) and heat stability tests (53°C for 60 min).

Main Results:

• PK measurement is rapid but requires careful interpretation.
• White blood cell PK activity differs significantly from red blood cell PK.
• Specialized assays can detect abnormal molecular characteristics of PK, particularly in acquired deficiency.

Conclusions:

• Accurate PK measurement necessitates red blood cell isolation to avoid interference from higher-activity white blood cell PK.
• Thermostability and low substrate concentration assays are vital for identifying atypical PK variants.
• Acquired PK deficiency may result from inhibitors affecting enzyme structure or function.