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
Serum Iron
Ferritin
Total Iron Binding Capacity
% Transferrin Saturation				20-55%
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

Lab Test Reference Intervals

Test	Reference Interval	Clinical Relevance	Interferences	Notes
Sodium	135 - 145 mmol/L
Potassium	3.5 - 5.0 mmol/L
Chloride
pH
pO2
pCO2
[HCO3-]
Glucose, fasting	4.1 - 5.6 mmol/L
Glucose, random
Total Bilirubin
Unconjugated Bilirubin
Conjugated Bilirubin
eGFR	>2.0 mL/s			Preferred over creatinine clearance
Urine flow rate	0.05 mL/s
Creatinine (serum)	62 - 115 μmol/L (male) 53 - 97 μmol/L (female)		↑ Hemolysis ↓ Icterus ↓ Lipemia Ammonium heparin Non-specific chromogens
Creatinine (urine, 24h)	9 - 18 mmol/d (male) 7 - 16 mmol/d (female)			Inaccuracies may arise from improper urine measurement or tubular secretion.
Creatinine Clearance	1.42 - 2.08 mL/s (male) 1.24 - 1.92 mL/s (female)			<0.63 mL/s is markedly decreased High serum creatinine may over-estimate CC.

Blood Gas Results

Test	Reference Interval	Clinical Relevance	Notes
Sodium	135 - 145 mmol/L
Potassium	3.5 - 5.0 mmol/L
Chloride
pH	7.35 - 7.45
pO2
pCO2	35 - 45 mmHg
[HCO3-]	21 - 28 mmol/L