Delay in sample receipt can cause:
- Increases in potassium, magnesium, phosphate, AST and LDH
- Decreases in glucose, occasionally sodium
Please note: refrigeration of samples may result in falsely elevated potassium levels
Common problems affecting blood test results
There are a number of non-pathological factors that can influence levels of specific analytes, giving falsely elevated or reduced levels. If you require more information regarding the effects of these factors on the outcome of an individual test result please contact the Duty Biochemist.
Haemolysis can be caused by expulsion of blood via needles, over-vigourous mixing of samples, storage of blood in deep freeze, or samples left in hot places. Haemolysis can cause:
- Increases in potassium, magnesium, phosphate, AST and LDH
- Decreases in glucose, occasionally sodium
Icterus is caused by high concentrations of bilirubin in sample (> 275 umol/L), and can cause:
- Decreases in creatinine
- May also affect bone/liver analytes
Lipaemia is caused by high concentrations of triglycerides in samples, and can cause:
- Decreases in sodium and glucose
- Interference in the majority of analytes
Other samples issues include:
- Prolonged venous stasis
- Vigorous exercise
- Certain drug treatments
- Radio-dyes/injections
- Sunlight exposure
- Drip contamination
- Non-fasted patient
All biochemical results are subject to a degree of uncertainty of measurement. This may be due to a range of factors, including:
- Biological variation within individuals
- Analytical measurement imprecision
- Pre-analytical factors