PREANALYTICAL VARIABLESPREANALYTICAL VARIABLES

Tapeshwar Yadav

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

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.

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

CONTROLABLE VARIABLES

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

PHYSIOLOGICAL

POSTURE

BLOOD VOLUME HEART RATE & BLOOD PRESSURE GFR ORTHOSTATIC PROTEINURIA

PROLONGED BED REST

FLUID RETENTION CK & K+

EXERCISE

BLOOD GLUCOSE LACTATE URATE PLASMA LIPIDS HORMONES FFA CREATININE BUN.

PHYSICAL TRAINING

SERUM ENZYMES OF MUSCULAR ORIGIN NPN

T4

LIPID

CIRCADION VARIATION

CORTISOL RENIN& ALDOSTERONE TSH GROWTH HORMONE

TRAVEL GLUCOSE TGL.

DIET HIGH PROTEIN FAT SUCROSE & CARBOHYDRATE

FOOD INGESTION

FASTING & POST PRANDIAL ALKALINE TIDE AFTER MEAL GTT SPECIFIC FOOD

CAFFEINE

VEGETARIANISM LIPID URINARY pH VIT B₁₂.

MALNUTRITION

PROTEIN (S) LIPID T4 TSH.

FASTING & STARVATION

BLOOD GLUCOSE INSULIN GLUCAGON LYPOLYSIS KETOGENESIS BR. CHAIN AMINO ACIDS PROTEIN (S) URINARY EXCRETION OF NH₃ & CREATININE.

LIFE STYLE

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

ALCOHOL

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

DRUGS

SIDE EFFECTS

THIAZIDES- HYPERGLYCEMIA, PHENYTOIN- BILIRUBIN

CONJUGATING ENZYMES.

RECREATIONAL SUBSTANCES AMPHETAMINES -FFA

MORPHINE -AMYLASE&LIPASE

HEROIN – CHOLESTEROL,THYROXIN

NONCONTROLABLE VARIABLES

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.

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.

SEX

CH. CHANGES AFTER PUBERTY- -ENZYMES -LIPID -NPN

RACE

TOTAL PROTEIN ALBUMIN GLUCOSE TOLERANCE Hb

ENVIRONMENTAL

ALTITUDE AMBIENT TEMPERATURE RESIDENCE SEASONAL

MEDICAL CONDITIONS

OBESITY PREGNANCY STRESS FEVER