Common Blood Tests

Question 1

What is an FBC test?

Answer 1

Full blood count:

• RBC
• WBC (neutrophils, monocytes, basophils, eosinophils)
• Platelets

WBC types, size and shape of cells

Question 2

Why might an FBC be done?

Answer 2

• Hypertension (too many RBC = thicker and increase BP)
• Heart disease
• COPD
• Diabetes
• Any prolonged or recurrent infection
• Cancer (undergoing chemo)
• Inflammatory dieseases requiring disease modifying anti-rheumatic drugs e.g. methotrexate
• Anaemia

Question 3

What is an ESR test?

Answer 3

Erythrocyte sedimentation rate:
Indicates inflammation because it affects RBC and prolongs time it takes to spin down in centrifuge. Influenced by age and gender, and should be measured within 2 hours of blood taken for accuracy

Question 4

What is a RFT test (or U and Es)?

Answer 4

Kidney or renal function test/ urea and electrolytes:
Measures level of urea, creatinine, electrolytes inc. Na, K, Cl and HCO3-

Also IDs glomerular filtration rate (eGFR)

Question 5

Why might an RFT/U and Es be needed?

Answer 5

• Kidney disease
• Hypertension
• Diabetes
• Specific meds e.g. anti-hypertensives

Question 6

What is an LFT?

Answer 6

Liver function test:
Measures level of liver enzymes e.g. alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate aminotransferase (AST) - abnormal levels may indicate liver disease.
Measures albumin (main protein prod), total protein, bilirubin (jaundiced if high levels in blood), and gamma-glutamyl transferase (GGT) - high levels may indicate alcohol abuse/ liver disease

Question 7

Why might a LFT be needed?

Answer 7

• Help diagnose/monitor liver disease

- Precaution after starting drugs e.g. statins to check not causing liver damage

Question 8

Why might Ca levels be checked?

Answer 8

• Kidney stones
• Bone disease
• Neurological disease
• Kidney disease
• Thyroid disease, cancer, malnutrition, intestinal disease
• Symptoms of HIGH Ca inc. fatigue, weakness, anorexia, vomiting, constipation, thirst, urinary frequency
• Symptoms of LOW Ca inc. abdominal cramps, muscle cramps, tingling fingers

Question 9

What random blood glucose level indicates diabetes?

Answer 9

11.1 mmol/L or more, confirmed with fasting test

Question 10

What fasting blood glucose level indicates diabetes?

Answer 10

7.0 mmol/L or more, usually repeated

Question 11

What if blood glucose levels are borderline?

Answer 11

Oral glucose tolerance test - overnight fast then glucose drink, blood sample taken 2 hours later, 11.1 = diabetes

Question 12

Why might glycated Hb be measured? (HbA1C)?

Answer 12

Indicates levels of circulating glucose in the blood stream over past 3 - 4 months.

More useful to determine overall diabetic control as fasting glucose only indicates intermediate glucose level

Question 13

What is a thyroid function test?

Answer 13

Helps diagnose thyroid disorders and monitor people with hypothyroidism who take thyroxine, and hyperthyroidism who take other types of drugs.
Newborns checked for inherited thyroid problems
First test usually for thyroid stim. hormone responsible for stim. prod of hormones T4 and T3.

Question 14

What is a lipid profile test?

Answer 14

Measurements of chol, trigly, LDLs and HDLs
Hyperlipidaemia: unhealthy diet or inherited, important risk factor for heart disease/strokes
Diagnosis usually after fasting blood test, high LDL levels associated with higher risk or HD and should be

Question 15

What is the international normalised ratio (INR)?

Answer 15

Measure of how much longer it takes blood to clot than normal (so if 2.0, 2x as long). Useful for patients taking warfarin - blocks vit K and depletes CFs so inhibits clotting. Useful for patients with:

• Atrial fibrillation
• DVT or Pulm. embol.
• Mech heart valves/ heart valve disease

Warfarin dosage personal and v. specific
Blood sample bottles contain heparin - stops clotting