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Paediatric Laboratory Medicine

Complex I

Clinical Significance

To provide instructions for determining the rate of NADH oxidation in mitochondria as a result of electron transfer from NADH to ubiquinone (mitochondrial Complex I activity).

Test Name

Complex I

Alternate Name/ Synonym

NADH Ubiquinone Reductase


Mitochondrial Disease


Spectrophotometric Measurements at 340nm

Turn Around Time

Tissue Biopsies: Fresh - 5 business days


  • Systemic Mitochondrial Syndromes
  • Leigh's

Specimen Type

  • Fresh Muscle Biopsy (only)

Minimum Specimen Requirements

  • 250-300 mg of muscle

Optimal Collection Time

Until 2:30pm  Monday-Friday


Transport from Pathology in dish on ice.

Special Requirements

Call to book (ext. 205989) at least 24 hours in advance for full Mitochondrial Enzyme screening on isolated mitochondria (Fresh specimen). Pick up from Pathology.

Shipping and Contact Information

The Hospital for Sick Children
Rapid Response Laboratory
170 Elizabeth Street, Room 3642
Toronto, ON
M5G 2G3
Phone: 416-813-7200
Phone: 1-855-381-3212

Reference Range

  • Muscle mitochondria: 59.49-327.78 nmol/mg/min, CI/CS: ≥0.1