Common Lab Tests

Question 1

Prothrombin time

Answer 1

Time taken for blood to clot, check for bleeding problems

Usually given as INR

• normal 11-13.5secs
• prolonged means blood taking too long to clot possibly due to liver disease, Vit K deficiency or clotting factor deficiency

Question 2

Apartate Aminotransferase (AST) level

Answer 2

Normal ranges

• female is 6 - 34 IU/L
• male is 8 - 40 IU/L

High is a sign of liver damage or damage in an organ that makes it i.e. heart or kidney

Question 3

Alanine Ainotransferase (ALT) level

Answer 3

More liver specific than AST

Normal ranges

• female is 5 - 38 IU/L
• male is 10 - 50 IU/L

If high, indicative of liver damage

Question 4

Fecal calprotectin

Answer 4

Indicates inflammation in bowel i.e. Crohn’s/Ulcerative Colitis

Question 5

Erythrocyte Sedimentation Rate

Answer 5

Measures how quickly RBCs settle at bottom of a test tube

If raised, indicative of inflammation

Normal Ranges

• female is 0 - 29 mm/hr
• male is 0 - 22mm/hr

Question 6

HbA1c

Answer 6

For normal, non-diabetic adults, normal is 6% or 42mmol/mol

People with diabetes should aim for 6.5% or 48mmol/mol

Question 7

TSH

Answer 7

Normal is 0.4 - 4mU/L

If higher then likely hypothyroid, if low then possible hyperthyroid

Consider in conjunction with T3 and T4

Question 8

Free T3

Answer 8

Normal 4 - 8.3

Low t3 could indicate hypothyroidism, high hyperthyroidism

Consider in conjunction with TSH and T4

Question 9

Free T4

Answer 9

Normal 10 - 24

Low possible hypothyroidism, high possible hyperthyroidism

Consider in conjunction with T3 and TSH

Question 10

CSF Opening pressure

Answer 10

Normal 10 - 20 cm H2O

High suggests raised ICP

Question 11

CSF

Answer 11

Appearance; clear, colourless

Total protein; 15 to 60 mg/100ml

Gamma globulin; 3-12% total protein

CSF glucose; 50 - 80 mg/100mL

CSF cell count; 0 - 5 WBCs, 0 RBCs

Question 12

TSH receptor antibodies

Answer 12

Normal <0.9 U/L

Most commonly requested in pregnant women with current active Grave’s to prevent neonatal thyrotoxicity

MOST HELPFUL FOR GRAVE’S

Question 13

Thyroid peroxidase antibody

Answer 13

Normal <35IU/mL

May be high in Hashimoto’s and graves

Question 14

Cardiac Troponin

Answer 14

Released when heart muscle is damaged

Normal <14ng/L

Question 15

Urea

Answer 15

Kidney function

Normal 7 - 20mg/dL (2.5 to 7.1 mmol/L)

if high, can indicate renal dysfunction

liver disease or damage can lower the urea

Question 16

Creatinine

Answer 16

Measured in both blood and urine

Using this result your eGFR (estimated glomerular filtration rate) is worked out

Normal 60 - 110 micromoles/l

Question 17

ABGs

Answer 17

Normal PaCO2 = 38 - 42 mmHg

Normal pH = 7.38 - 7.42

Oxygen saturation = 94 - 100%

Bicarbonate = 22 - 28 mEq/L

Question 18

Albumin

Answer 18

Normal 3.4 - 5.4 g/dL

If low can indicate malnutrition, liver disease or an inflammatory disease

high can be caused by acute infections, burns and stress from surgery or MI

Question 19

Bilirubin

Answer 19

Normal < 1.2mg/dL (1md/dL for <18s)

If high possible problem in liver, GB, RBCs

Question 20

Lipase

Answer 20

Normal 0-160U/L

If high (3x normal) then likely pancreatitis or pancreatic damage

If low pancreatic damage

Question 21

Amylase

Answer 21

Normal 28 - 35 U/L

If high (3x norm) likely pancreatitis

Low in damaged pancreas

Question 22

Potassium

Answer 22

Normal 3.5 - 5 mEq/L

high may be due to kidney dysfunction

low may be due to diarrhoea, vomiting, adrenal gland disorders or diuretic use

Question 23

LFTs (general)

Answer 23

ALT and AST; raise in liver problem, ALT more liver specific

ALP and GGT; obstructive/cholestatic condition

Bilirubin raised in jaundice

Albumin low in liver conditions

Question 24

Na

Answer 24

Normal Na is 135 - 145

Question 25

Eye pressure

Answer 25

12-22 mmHg

Question 26

Calcium

Answer 26

2.2 - 2.6mmol/L