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Paediatric Laboratory Medicine

Citrate Synthase

Clinical Significance

To determine the activity of citrate synthase

Test Name

Citrate Synthase

Alternate Name/ Synonym

  • CS


Mitochondrial Disease


Spectrophotometric Measurements at 412nm

Turn Around Time

  • Fibroblasts: 3 weeks - 3 months
  • Tissue Biopsies: Fresh - 5 business days
  • Tissue Biopsies: Frozen - 1 month


Indicator for mitochondrial proliferation.

Specimen Type

  • Fibroblasts
  • Muscle
  • Liver
  • Kidney
  • Heart

Minimum Specimen Requirements

  • 1 dish for subculturing
  • 20 dishes for mitochondrial isolation from fibroblasts
  • 30-50 mg from muscle biopsy/autopsy for testing on muscle homogenate
  • 250- 300 mg for mitochondrial isolation from fresh muscle biopsy

Optimal Collection Time

  • For fibroblasts, amniocytes or CVS cell cultures: anytime
  • Fresh biopsy: until 2:30 pm, Monday-Friday


  • For fibroblasts: Room temperature
  • Frozen biopsy: transport on dry ice
  • For fresh muscle biopsy: transport from Pathology in dish on ice

Special Requirements

For fresh biopsy: call to book (ext. 205989) at least 24 hours in advance for full Mitochondrial Enzyme screening on isolated mitochondria. 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

  • Fibroblast mitochondria: 36.50-80.34 nmol/mg/min
  • Muscle homogenate: 3.56-9.24 µmol/min/g wet wt
  • Muscle mitochondria: 309.25-924.00 nmol/mg/min
  • Kidney homogenate: 1.27-9.70 µmol/min/g wet wt 
  • Liver homogenate: 2.18-9.07 µmol/min/g wet wt
  • Endocardial homogenate: 158.78-913.31 nmol/mg/min

Note: Reported in combination with other respiratory enzymes.  


Citrate Synthase is a mitochondrial enzyme that resides in the matrix of these organelles. It is a marker for mitochondrial purity and proliferation. The enzyme’s measurement is used as an indication of mitochondrial integrity.