This document discusses preanalytical variables that can affect lab test results. It identifies controllable variables like diet, lifestyle factors, medications, and herbal preparations. Uncontrollable variables include biological influences, environmental factors, and underlying medical conditions. Both short-term and long-term cyclical changes are outlined as influencing lab results. Metrics for assessing biological variability are also presented.

18. Dr Om Prakash Sharma. MD Student

19. Preanalytical variables
Controllable variables:-
Posture
Prolonged bed rest
Exercise
Physical fitness and training
Circadian variation
Travel
Diet
Life-style
Stimulants
Drugs
Herbal preparations
Recreational drug ingestion

20. Diet
Food ingestion
Ingestion of specific foods and Beverages
Bran
Food constituents
Caffeine
Vegetarianism
Malnutrition
Long term fasting and starvations

21. Noncontrollable Variables
Biological Influences
Age
Sex
Race
Environmental factors
Altitude
Ambient temperature
Place of residence

22. Life Style
Smoking
Alcohol Ingestion
Drugs:-
Vitamines
Oral contraceptive pills
Sleeping pills
Penicillin derivatives
Opiates
Diuretics
Phenytoin
Spironolactones
Mannitol
Ascorbic acid

23. Herbal preparations
St.johns wort
Ginseng
Grapefruit juice
Garlic ingestion
Ginkgo biloba
Aloe vera
Senna
Cascara sagrada
Germander
Bishops weed
Tonka beans
Comfrey

24. Noncontrollable Variables
Biological influences
Age
Sex
Race
Environmental factors
Altitude
Ambient temperature
Place of residence

25. Long term cyclical changes
Seasonal influences
Influence of menstrual cycle
Underlying medical conditions
Obesity
Blindness
Pregnancy
Stress
fever

26. Contd.
Shock
Trauma
Transfusion
Infusions

27. Biological Variability
Intraindividual
Interindividual
Calculating total variation
Reference change values
Index of individuality
Index of heterogeneity
Reliability coefficient
Quality specifications for total error allowable
Assessment of mode of reporting test results