4. Influence of medical procedures and medicines on the clinical laboratory results

Question 1

What are the 4 Mechanisms of Drug Interference in Laboratory Results?

Answer 1

1. Physical
2. Chemical
3. Pharmacological
4. Drug-Drug

Question 2

1| What are the Physical Drug Interference in Lab Results?

Answer 2

Standard Colorimetric

Photometric

Fluorometric

Question 3

2| What are the Chemical Drug Interference in Lab Results?

Answer 3

Measured as Analytes = Due to Similar Chemical Structure

Long-Lasting Effects = In IV Administration

E.g. EDTA in Heavy Metal Intoxication

Question 4

3| What are the Pharmacological Drug Interference in Lab Results?

Answer 4

Pharmacological Activity of Drug

Toxic Activity of Drug

Question 5

3| What Levels are Affected due to Pharmacological Drug Interference?

Answer 5

INCREASED Prothrombin = Due to Sodium Warfarin

INCREASED Potassium = Due to Thiazide Diuretics; Glucocorticoids

INCREASED Glucose = Due to Thiazide Diuretics; Glucocorticoids

Question 6

4| What are the Drug-Drug Interference in Lab Results?

Answer 6

Produce Alterations when Interacting with OTHER Drugs

Question 7

4| What Levels are Affected due to Drug-Drug Interference?

Answer 7

INCREASED Prothrombin Time =

Due to COLIFIBRATE + WARFARIN

Question 8

4| What Other Drug-Drug so Medications can Interfere with Lab Results?

AND

What is Advised?

Answer 8

Thyroid Supplement Therapy

Anti-Hypertensives

Advised** to STOP Meds at Morning of Blood Collection

Question 9

What can Alter the Lab Result for H.Pylori, in a Fecal Antigen Test?

and How?

Answer 9

Antibiotics

PPIs

• DECREASE Gastric Load of H.Pylori
• Hence the NEGATIVE -ve Result

Question 10

Which Medicines May Cause a Biological Effect?

Answer 10

Antibiotics

CV Medicines

NSAIDs

GI Medications

Question 11

Which Medication has a LOWERING Biological Effect?

AND On What?

Answer 11

WARFARIN Causes:

INCREASED International Normalised Ratio, INR

Question 12

Which Medication has an INCREASED Biological Effect

AND On What?

Answer 12

Long-Term Use of:

• METFORMIN
• PPIs

Causing DECREASED Vitamin B12

Question 13

What does Chemotherapy DECREASE the Level of?

Answer 13

WBC Count

Steroids

Question 14

What does Chemotherapy INCREASE the Level of?

Answer 14

Blood Glucose Levels

Question 15

Which Medical Procedures can Cause an INCREASE in CPK Level?

Answer 15

Intramuscular, i.m Injections

Muscle Biopsies

Laparoscopies

Question 16

What Physical Examination Causes INCREASED PSA Level?

Answer 16

Palpation of Prostate

Question 17

Which Therapies Cause Significant ELEVATION of Uric Acid?

Answer 17

Cytostatic Therapy

Radiotherapy