Physiological Variables that Influence Lab Test Results Flashcards
PREANALYTICAL CONSIDERATIONS
IN PHLEBOTOMY
- Preanalytical- before analysis
- Begins when a test is ordered and ends when testing begins
- Basal state: resting metabolic state of the body early morning after approximately 12 hours fasting
- Basal state is influenced by a number of physiologic variables such as age, gender, and conditions of the body that cannot be
eliminated
Physiological Variables that Influence
Laboratory Test Results
-Age
-Jaundice
-Altitude
-Intramuscular Injection
-Dehydration
-Position
-Diurnal Variation
-Pregnancy
-Drug Therapy
-Smoking
-Exercise
-Stress
-Gender
-Temperature & Humidity
AGE
* RBC and WBC values ____ in newborns
* Kidney function (creatinine clearance) ____ with age
higher
decrease
ALTITUDE
* Red blood cell (RBC) counts elevated at _____ altitude
higher
DEHYDRATION
* Hemoconcentration
_____
RBCs, enzymes, iron (Fe), calcium (Ca), sodium (Na)
DIET
LIPIDS
ELECTROLYTES
AMMONIA
GLUCOSE
Tests that requires FASTING:
- FBS
- Glucose tolerance test
- Triglycerides & lipid panel
- Gastrin
- Insulin
- Aldosterone & renin
- Electrolytes
DIURNAL/CIRCADIAN VARIATIONS
Melatonin levels are affected by light
●Renin and thyroid-stimulating hormone (TSH)
Cortisol levels
Exhibit diurnal variation with highest levels in the morning
DRUG THERAPY
● Chemotherapy drugs can cause a decrease in blood cells, especially
WBCs and platelets
● Many drugs are toxic to the liver
● increase levels of liver enzymes:
○ Aspartate aminotransaminase (AST)
○ Alkaline phosphatase (ALP)
○ Lactate dehydrogenase (LDH)
● Steroids and diuretics: increase amylase and lipase
FEVER
○ Increases hormones insulin and glucagon
○ increases cortisol
GENDER
RBC, hemoglobin (Hgb), andhematocrit (Hct)
normal values are
higher for males than for females
EXERCISE
● Arterial pH and PCO2 levels are reduced
● Glucose can be elevated by moderate muscular activity
● Potassium (K+) is increased in the plasma
● Skeletal muscle enzymes creatine kinase (CK) and lactate dehydrogenase
(LDH) are increased by exercise
INTRAMUSCULAR INJECTION
increases levels of creatine kinase (CK) and the skeletal muscle
fraction of LDH
JAUNDICE
● icteric : deep yellow to yellow-brown color of serum or plasma
● interferes with chemistry tests based on color reactions
BODY POSITION
● from supine to an upright sitting or standing position
causes blood fluids to filter into the tissues, decreasing
plasma volume
● Increased: protein in nature or bound to protein—such as
aldosterone, bilirubin, blood cells, calcium, cholesterol, iron,
protein, and renin
● increase in potassium (K) levels
PREGNANCY
● lower RBC counts
SMOKING
● Increased cholesterol, cortisol, glucose, growth hormone, and
triglyceride levels and WBC counts
● Chronic smoking : decreased pulmonary function and increased
RBC counts and hemoglobin levels
● Smoking can also affect the body’s immune response, lowering the
conc. of immunoglobulins
STRESS
● Increases in WBC counts
● Decrease serum iron levels
● Increase adrenocorticotropic hormone(ACTH), catecholamine, and
cortisol levels
TEMPERATURE and HUMIDITY
hemoconcentration
increase with ingestion of fatty foods
➢Lipids
UREA increase in patients on high-protein diets
Ammonia,
altered by drinking excessive water
➢Electrolytes
e increase with the ingestion of carbohydrates
➢Glucose
Increase at night and decrease during day
Melatonin levels are affected by light
