20. Laboratory - Conventional Flashcards
1
Q
Why is case taking essential?
A
Identify what is likely to be causing symptoms
Screen for potential systemic illnesses that might be undiagnosed
Identify why a patient has come to see you
2
Q
What percentage of the information obtained from a case history makes up a diagnosis?
A
80%
3
Q
What are good case-taking skills?
A
Developing rapport Using open-ended questions Good listening Empathy Clinical curiosity Follow-up questions Asking questions in a way the patient will understand Communication
4
Q
What are conventional diagnostic techniques?
A
X-rays Ultrasound MRI CT scan Laboratory tests
5
Q
What do x-rays investigate?
A
Dense materials:
Bones
Tumours
Blood clots
6
Q
What do x-rays increase the risk of?
A
Mutations
7
Q
What do ultrasounds investigate?
A
Soft tissues
8
Q
What do ultrasounds use for imaging?
A
Sound waves
9
Q
What do MRIs investigate?
A
Dense and soft tissue
10
Q
What do CT scans use for imaging?
A
Powerful x-rays
11
Q
What do CT scans investigate?
A
Dense and soft tissue
12
Q
What do laboratory tests investigate?
A
Blood
Stool
Urine
13
Q
What can blood test readings indicate?
A
Disease processes
14
Q
Why is it important to repeat blood tests?
A
A snapshot in time
Easily influenced by factors such as time of day, food eated
15
Q
What may not show up in blood tests?
A
Sub-clinical hypothyroidism
16
Q
What does a full blood count measure?
A
Amount of haemoglobin No of RBC % of RBC vs total blood volume Volume of RBC Average amount of haemoglobin in RBC No of WBC % of different WBC No of platelets
17
Q
What is the RBC count?
A
No of RBC in a quantity of blood
18
Q
What is the haemoglobin count?
A
Amount of Hb in a quantity of blood
19
Q
What can low RBC/low Hb indicate?
A
Anaemia
Bone marrow diseases
20
Q
What can high RBC/low Hb indicate?
A
Dehydration
Polycythaemia
21
Q
What does haematocrit measure?
A
Amount of blood volume taken up by RBCs (%)
22
Q
How is haematocrit calculated?
A
Centrifugation
23
Q
What can low haematocrit indicate?
A
Anaemia
24
Q
What can high haematocrit indicate?
A
Dehydration
Polycythaemia
25
What is mean corpuscular volume (MCV)?
Average volume (and hence size) of a RBC
26
What can low MCV indicate?
Microcytic anaemia
27
What can high MCV indicate?
Megaloblastic anaemia
28
What is mean corpuscular haemoglobin (MCH)?
Amount of haemoglobin in one RBC
29
Why is MCH similar to MCV?
The value is directly proportional to the amount of haemoglobin and the size of the erythrocyte
30
What can low MCV indicate?
Microcytic anaemia
31
What can high MCV indicate?
Macrocytic anaemia
32
What is RBC distribution width (RDW)?
Indication of the variation in RBC size
33
What is the variation in RBC size also known as?
Anisocytosis
34
What can high RDW indicate?
Anaemias due to various deficiencies - iron, B12, folate
35
What happens when there is insufficient iron for normal haematopoiesis?
Bone marrow produces microcytes (microcytic anaemia)
36
When does RDW increase rapidly?
In the initial stages when the small RBCs are mixed in with normal sized RBC
37
What is haematinics?
The nutrients required for the formation of RBC
38
Which nutrients are needed for the production of RBC?
Ferritin (iron)
Vit B12
Folate (B9)
39
What is ferritin?
An intracellular protein that stores iron
40
Where is most ferritin produced?
Liver
41
What can raised iron levels indicate?
Inflammation
| Liver disease
42
What can low iron levels indicate?
Iron deficient anaemia
43
What is a differential WBC count?
The quantity of each type of leukocyte present in the blood specimen
44
What is released by WBCs in response to an acute infection, trauma or inflammation?
Colony-stimulating factor
45
What does colony-stimulating factor do?
Increases bone marrow production of leukocytes
46
What is a low WBC count called?
Leukopenia
47
What is a high WBC count called?
Leukocytosis
48
What can leukopenia be a result of?
```
Chemo
Radiotherapy
Aplastic anaemia
Immune suppressive medication
Stress
Alcohol
HIV/AIDS
Viral infections
```
49
What can leukocytosis be a result of?
Bacterial infections
Inflammation
Leukaemia
50
What is a low thrombocyte count called?
Thrombocytopenia
51
What is a high thrombocyte count called?
Thrombocytosis
52
What can thrombocytopenia be a result of?
```
Leukaemia
Lymphoma
Viral infections
Heavy alcohol intake
Chemo
Some AI diseases (RA, SLE)
Massive blood loss
```
53
What can thrombocytosis be a result of?
Exaggerated response to an infection
Splenectomy
Haemolytic anaemias (spleen too busy to break down thrombocytes)
54
What can erythrocyte sedimentation rate (ESR) be a measure of?
Inflammation
55
Why should ESR measurements be read with caution?
High sensitivity but low specificity
| can be indicative of many diseases
56
How is the ESR measured?
Anticoagulated blood is placed in an upright tube
Rate at which the red blood cells fall (sediment) in an hour is measured
Reported in mm/h
57
What happens in blood when an inflammatory process is present?
High serum fibrinogen causes red blood cells to stick together
Causes more rapid sedimentation
58
When to ESR levels tend to rise?
With age
| Generally higher in women
59
What can an ESR of up to 50 mm after one hour indicate?
Inflammatory diseases e.g. RA, SLE
Hypothyroid function
Menstruation
60
What can an ESR of 50-100 mm after one hour indicate?
```
Chronic polyarthritis
Appendicitis
Acute bacterial infections
Chronic liver disease
Post MI
```
61
What can an ESR of over 100 mm after one hour indicate?
Malignancies
Tuberculosis
Sepsis
Peritonitis
62
What is c-reactive protein (CRP)?
General marker for inflammation
63
What is CRP?
Acute phase protein produced by the liver
64
Why should CRP measurements be read with caution?
Many things can elevate CRP
65
Which is a better indicator of inflammation - ESR or CRP?
CRP
66
Why is CRP a better indicator of inflammation?
Can monitor fast changes as it doesn't depend on fibrinogen or immunoglobulin levels
Not affected by RBC numbers and shape
67
What can raised CRP be indicative of?
Inflammatory disorders e.g. RA, Crohn's
Tissue injury e.g. burns, necrosis, MI
Infections - bacterial
Malignancy
68
What links raised CRP and CVD?
High CRP levels are associated with poorer prognosis in atherosclerosis CVD
Inflammation a key component of atherosclerosis development
69
What can raised antinuclear antibodies (ANAs) be indicative of?
SLE
70
What can raised antiphospholipid antibodies be indicative of?
SLE
71
What can raised rheumatoid factor be indicative of?
RA
72
What percentage of RA patients are tested positive for RF?
80%
73
What can raised IgA anti-tissue transglutaminase be indicative of?
Coeliac's disease
74
What can raised endomysial antibodies (EMAs) be indicative of?
Coeliac's disease
75
What can thyroid antibodies be indicative of?
AI thyroid diseases
76
What can blood lipids be linked with?
CVDs
77
What does a lipid profile include?
Total cholesterol
LDL
HDL
Triglycerides
78
What do low density lipoproteins (LDL) do?
Carry cholesterol from the liver to body cells
79
What do high density lipoproteins (HDL) do?
Collect cholesterol from the body's tissues and return it to the liver
80
What is hyperlipidaemia?
Presence of elevated lipids in the blood
81
What can cause hyperlipidaemia?
```
Genetic - familial
Obesity
DM
Hypothyroidism
High sugar consumption
Alcohol abuse
Kidney diseases
Cushing's disease
Certain meds e.g. steroids, COCP
```
82
What is blood glucose testing useful for?
Diagnosis and monitoring of diabetic patients
83
What is recommended as a diagnostic test for diabetes?
Glycated haemoglobin (HbA1c)
84
What does the HbA1c test do?
Gives an average of previous two/three months' blood sugar levels
85
What does the HbA1c test measure?
Glucose bound to haemoglobin
86
What symptom can trigger a request for thyroid function tests?
Fatigue
87
What is HIGH TSH and LOW thyroid hormone levels indicative of?
Hypothyroidism
| Hashimoto's, post-thyroidectomy, post-radioactive iodine, iodine deficiency
88
What is LOW TSH and LOW thyroid hormone levels indicative of?
Hypothyroidism
| Pituitary tumour
89
What is LOW TSH and HIGH thyroid hormone levels indicative of?
Hyperthyroidism
| Grave's disease
90
What is HIGH TSH and HIGH thyroid hormone levels indicative of?
Hyperthyroidism
| Pituitary tumour
91
Which sex hormones are commonly measured?
```
Oestrogen
Progesterone
FSH
LH
Testosterone
Prolactin
```
92
Why to blood samples in women need to be taken at a specific time in the menstrual cycle?
As hormones fluctuate throughout the month
93
What are the typical hormonal changes during menopause?
```
Reduced oestrogen
Reduced progesterone
Decline in ovulation
High FSH
High LH (negative feedback due to reduced O + P
```
94
What are the typical hormonal changes during PCOS?
```
Low sex hormone binding globulin (SHBG)
High LH
Hyperinsulinemia
High blood glucose
Increased androgens
```
95
What does high unconjugated bilirubin indicate?
Gilbert's syndrome (reduced activity of the enzyme which conjugates bilirubin)
Haemolytic anaemia
96
What does high conjugated bilirubin indicate?
Liver disease
| Biliary obstruction
97
What can albumin be a marker of?
Hepatic function
98
What does low albumin indicate?
Chronic liver disease
Nephrotic syndrome
Malnutrition
Oedema
99
What does high albumin indicate?
Acute infections
100
What is ALP?
Liver enzyme produced from bile duct cells
| Sensitive to any bile duct obstruction
101
What can raised ALP indicate?
Acute liver damage
| Liver tumours
102
What is GGT?
Liver enzyme produced by liver cells
103
When is GGT released?
Into the blood following liver cell damage or destruction
104
What can raised GGT indicate?
All liver diseases
| Biliary tree disease
105
What can raised ALT indicate?
Leakage from damaged liver cells
106
What can raised AST indicate?
Alcohol-induced liver disease
Cirrhosis
Hepatitis
107
What can raised pancreatic enzymes indicate?
Pancreatitis
| Pancreatic cancer
108
Why do pancreatic enzymes become raised in pancreatitis?
Proteolytic enzymes become activated in the pancreas, rather than intestines, and enter the blood
109
Which enzymes are useful to test in acute pancreatitis?
Serum amylase
| Serum lipase
110
What can be tested to measure renal function?
Estimated glomerular filtration rate (eGFR)
Creatinine
Urea
Uric acid
111
Why should eGFR results be read with caution?
Calculated using blood creatinine
| Value can easily influenced by age, sex, muscle bulk and meat ingestion
112
What are patients advised to do before a renal function test?
Avoid eating meat 12 hrs before
113
What does a GFR of <15 indicate?
Renal failure
114
Types of blood glucose tests useful in the diagnosis and monitoring of diabetics?
Random
Fasting blood glucose
Two-hour oral glucose tolerance test (OGGT)
115
What does stool analysis begin with?
Observation
116
What can be observed in a stool analysis?
```
Colour
Odour
Consistency
Presence of blood
Mucus
Pus
```
117
What can stool microscopic analysis test?
```
Water concentration
Occult blood
Tumour markers
Calprotectin
Bacteria
```
118
What can occult blood in the stool be a sign of?
GIT malignancy
| Ulceration
119
What can tumour markers in the stool indicate?
Raised M2-PK
| Colorectal cancer
120
What can calprotectin in the stool indicate?
IBD
| NSAID use
121
Which bacteria can be tested for in the stool?
```
Salmonella
Campylobacter
C. difficile
E. coli
Shigella
Cholera
Protozoan
```
122
What can a skin prick test assess?
Immediate allergic response to multiple substances at once
123
What kinds of allergies can be tested for in a skin prick test?
```
Foods
Pollen
Certain drugs
Animal dander
Dust mites
```
124
What happens during a skin prick test?
Drop of each allergen applied to a certain point on skin
Each location is then pricked with a thin needle
Within 20-30 min the skin is observed for signs of an allergic response
125
What are the skin signs of an allergic response?
Raised, red, itchy bump
