Chemistry Specimen Processing

Separate serum/plasma from blood cells within 2 hours

• For serum, need to wait for specimen to clot first (20-30 min)

Store samples at 4C when not being run

For longer-term storage, store at minimum -20C

Analyte	Specimen Type	Collection Media	Collection Notes	Reference Interval
Sodium		Lithium heparin		135 - 145 mmol/L
Potassium		Lithium heparin		3.5-5.0 mmol/L
Glucose	Fasting			4.1 - 5.6 mmol/L
	Random
Creatinine	Urine, 24 hour
	Blood serum	Lithium heparin
Urea	Blood serum or plasma	Lithium heparin		2.1 - 7.1 mmol/L
	Urine, random		Use thymol preservative and refrigerate
	Urine, 24 hour		Use thymol preservative and refrigerate	430 - 710 mmol/day
Uric Acid	Blood serum or plasma	Lithium heparin
	Urine, 24 hour
Urinalysis	Urine, first morning midstream clean-catch preferred		Fresh samples <2h old

Special Samples:

• Keep on ice
  • Blood gases
  • Ammonia
• Protect from light
  • Bilirubin
  • Vitamin B12