Glucose, Plasma / CSF / Fluid

 

Specimen requirement

Plasma

CSF

Spot Fluid

Adult patient:

 

 Fluoride tube

 

Minimum blood volume: 2 mL

Adult patient:

 

 Fluoride tube

 

Minimum volume: 2 mL

 

Adult patient:

 

 Fluoride tube

 

Minimum volume: 2 mL

 

Paediatric patient:

 

Paediatric fluoride tube

 

Number of vials: 1

 

Minimum blood volume: 1.3 mL

Paediatric patient:

 

Paediatric fluoride tube

 

Number of vials: 1

 

Minimum volume: 1.3 mL

 

Paediatric patient:

 

Paediatric fluoride tube

 

Number of vials: 1

 

Minimum volume: 1.3 mL

 

Authorisation code required

No

No No

24 Hr available service

Yes

Yes

No

Method

Spectrophotometry

Reference interval

Plasma Glucose

1. Fasting plasma glucose (mmol/L):

Result alert limits: < 2.5; > 5.6 mmol/L

Fasting is defined as no caloric intake for at least 8 Hr.

The diagnosis of diabetes mellitus (DM) needs to be confirmed by repeat testing on a separate day or by OGTT.

(Source: modified from Diabetes Care 2010; 33 (Suppl): S62 - 9)

  • Plasma glucose concentration in healthy individuals is highly variable due to difference in age, individual’s glucose tolerance & recent carbohydrate intake.
  • Diabetes mellitus is diagnosed when fasting plasma glucose is > 7.0 mmol/L confirmed by repeat testing. Impaired fasting glucose is diagnosed when fasting plasma glucose is 5.6 - 6.9 mmol/L.
  • Plasma glucose concentration < 2.5 or > 11.1 mmol/L could be associated with potentially fatal hypoglycemic & hyperglycemic crises respectively. Both conditions warrant urgent medical attention and management.

(COCPath Consensus Statement: 8 - 2014)

 

2. 75 gm Oral Glucose Tolerance Test (mmol/L):

  Normal IFG IGT DM
0 min < 5.6 5.6 - 6.9 - > 7.0
120 min < 7.8 - 7.8 - 11.0 > 11.1

IFG: Impaired fasting glycaemia
IGT: Impaired glucose tolerance 
The test should be performed as described by the World Health Organisation, using a glucose load containing the equivalent of 75 gm anhydrous glucose dissolved in water. (Source: modified from Diabetes Care 2010; 33 (Suppl): S62 – 9)

For OGTT during pregnancy, please refer to the Obstetric Protocol of the Department of O&G, NTEC Cluster for reference.

 

3. Random plasma glucose:

Result alert limits: < 2.5; > 7.0 mmol/L

  • Plasma glucose concentration in healthy individuals is highly variable due to difference in age, individual’s glucose tolerance & recent carbohydrate intake.
  • Diabetes mellitus is diagnosed when random plasma glucose is > 11.1 mmol/L with classic symptoms of hyperglycemia or hyperglycemic crisis.
  • Plasma glucose concentration < 2.5 or > 11.1 mmol/L could be associated with potentially fatal hypoglycemic & hyperglycemic crises respectively. Both conditions warrant urgent medical attention and management.

(COCPath Consensus Statement: 8 - 2014)

(Source: Diabetes Care 2012; 35(Suppl): S64 - 71)

 

CSF Glucose

2.2 - 3.9 mmol/L

 

(Source: Roberts WL et al. Reference Information for the Clinical Laboratory. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 4th edn. Burtis CA, Ashwood ER and Bruns DE eds. Elsevier Saunders 2006; 2251 - 2318)

Clinical indication

Plasma:

 

Detection of hyperglycaemia and hypoglycaemia

 

Diagnosis and as a screening test for diabetes mellitus

 

Monitoring glycaemic control

 

CSF:


Aid in diagnosis of meningitis

Result interpretation

Plasma:

See reference interval above.

In patients with fasting plasma glucose levels between 5.6 - 6.9 mmol/L or random plasma glucose levels between 7.8 - 11.0 mmol/L, an oral glucose tolerance test (OGTT) should be performed.

Fasting plasma glucose levels < 5.6 mmol/L and / or random levels < 7.8 mmol/L make diabetes mellitus unlikely, and OGTT is not indicated.

Measurement of uncertainty

See table.

Frequency of measurement

Daily