Preanalytical variables

Defined as errors which occur when non analytical factors change the conc. of analytes,so the result do not reflect real the condition of the patient

1. PREANALYTICAL VARIABLESPREANALYTICAL VARIABLES



Tapeshwar Yadav
(Lecturer)
BMLT, DNHE,
M.Sc. Medical Biochemistry

2. Defined as errors which occur when non analytical
factors change the conc. of analytes,so the result
do not reflect real the condition of the patient.

3. PREANALYTICAL VARIABLES
CONTROLLABLE UNCONTROLLABLE

TEST & SAMPLE COLLECTION AGE
PHYSIOLOGICAL SEX
DIET RACE
LIFE STYLE ENVIRONMENT
STIMULANTS SEASON
DRUGS OBESITY
HERBAL PREGNANCY
RECREATIONAL SUBSTANCE STRESS
FEVER

4. CONTROLABLE VARIABLES

5. TEST & SAMPLE COLLECTION
Test conducted
Patient identification
Turn around time
Laboratory logs
Transcription errors
Patient preparation
Specimen collection
Separation ,aliquoting

6. PHYSIOLOGICAL

7. POSTURE
 BLOOD VOLUME
 HEART RATE & BLOOD PRESSURE
 GFR
 ORTHOSTATIC PROTEINURIA

8. PROLONGED BED REST
FLUID RETENTION
CK & K+

9. EXERCISE
BLOOD GLUCOSE
 LACTATE
URATE
PLASMA LIPIDS
HORMONES
FFA
CREATININE
BUN.

10. PHYSICAL TRAINING
SERUM ENZYMES OF MUSCULAR ORIGIN

NPN
T4
 LIPID

11. CIRCADION VARIATION
CORTISOL
RENIN& ALDOSTERONE
TSH
GROWTH HORMONE

12. TRAVEL
GLUCOSE
TGL.

13. DIET
HIGH PROTEIN
 FAT
SUCROSE & CARBOHYDRATE

14. FOOD INGESTION
 FASTING & POST PRANDIAL
 ALKALINE TIDE AFTER MEAL
 GTT


SPECIFIC FOOD
CAFFEINE

15. VEGETARIANISM
LIPID
URINARY pH
VIT B₁₂.

16. MALNUTRITION
 PROTEIN (S)
 LIPID
 T4
 TSH.

17. FASTING & STARVATION
BLOOD GLUCOSE
INSULIN
GLUCAGON
LYPOLYSIS
KETOGENESIS
BR. CHAIN AMINO ACIDS
PROTEIN (S)
URINARY EXCRETION OF NH ₃ &
CREATININE.

18. LIFE STYLE

19. SMOKING
NICOTINE
PLASMA EPINEPHRINE,
GLUCOSE & INSULIN
LACTATE
LIPIDS
CORTISOL
CARBOXYHEMOGLOBIN
GASTRIC JUICE
IMMUNOGLOBULINS
VIT B12

20. ALCOHOL
GLUCOSE
INHIBITION OF GLUCONEOGENESIS
LACTATE & URATE
 TGL & HDL
CORTISOL
GGT.

21. DRUGS
SIDE EFFECTS
THIAZIDES- HYPERGLYCEMIA,
PHENYTOIN- BILIRUBIN
CONJUGATING ENZYMES.

22. RECREATIONAL SUBSTANCES


AMPHETAMINES -FFA
MORPHINE -AMYLASE&LIPASE
HEROIN – CHOLESTEROL,THYROXIN

23. NONCONTROLABLE VARIABLES

24. BIOLOGICAL INFLUENCES
 
 BETTER AGREEMENT BETWEEN SERUM CONC OR
ACTIVITIES OF CONSTITUENTS IN MONOZYGOTIC THAN
IN DIZYGOTIC TWINS.
IN WOMEN & BLOOD GR ‘O’- Hb CONC < OTHER BOOD GR.

25. AGE
NEW BORN-
-CHANGES RELATED TO INFANTS
ADAPTATION TO INDEPENDENT EXISTENCE
-R.B.C COUNT & Hb CONC. Hb F,
PHYSIOLOGICAL JAUNDICE, BLOOD GLUCOSE,
PLASMA AMINO ACID CONC.
CHILDHOOD TO PUBERTY-
-PLASMA PROTEIN ,
ADULT-

ELDERLY-
-CREATINE CLEARANCE, T3, INSULIN.

26. SEX
CH. CHANGES AFTER PUBERTY-

-ENZYMES
-LIPID
-NPN

27. RACE

TOTAL PROTEIN
ALBUMIN
GLUCOSE TOLERANCE
Hb

28. ENVIRONMENTAL
ALTITUDE
AMBIENT TEMPERATURE
RESIDENCE
SEASONAL

29. MEDICAL CONDITIONS
 OBESITY
 PREGNANCY
 STRESS
 FEVER