Transcript Blood Tests - Revise4finals

Blood Tests & ABGs
© Dr Karan Wadhwa & Dr Tim Coughlin
www.revise4finals.co.uk
Objectives
• Discuss
– basic blood tests
– ABGs
• Use some case examples and practice
some sample questions
• Questions
Why?
Why do blood tests?
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Haematinics
Nutritional status
Exposure to toxic substances
Markers of infection
Hydration status
Renal function
Baseline before treatment
Etc…
What blood tests are available
to us?
• Full blood count
– Red cells, white cells, platelets
• Urea and electrolytes
– Sodium, potassium, urea, creatinine
• Liver function tests
– Bilirubin, total protein, albumin, ALP,ALT,GGT
• Inflammatory markers
– CRP, ESR
• Thyroid function tests
– TSH, T4,T3
Others
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Troponin I
Calcium/magnesium/phosphate
Glucose
Amylase
Clotting/INR/APTT
Patterns in disease
• Infective process e.g. Strep Pneumonia
– WCC - neutrophillia
– CRP
• Anaemia
– Macrocytic - High MCV
– Microcytic - Low MCV
– Normocytic - Normal MCV
• Renal dysfunction/dehydration
– Urea
– Creatinine
– Sodium
• Poor nutrition
– Albumin/Protein
• Liver function
– Clotting
– Jaundice
• Prehepatic - conjugated bilirubin, Coombs
• Hepatic - ALT
• Post hepatic - ALP/GGT
• Thyroid disease
– Hyperthyroidism - Low TSH, High T4
– Hypothyroidism - High TSH, Low T4
Arterial Blood Gases
• Procedure
• Results
– pH 7.35 - 7.45
– PCO2 4.7 - 6.0 kPa
– PO2 10.0-13.0
– HCO3 - 22.0 - 30.0
– Base excess +2 - -2
Logic behind blood gases
• Metabolic acidosis - pH , CO2 (N) HCO3 
– With respiratory compensation, CO2 may be 
• Metabolic alkalosis - pH , CO2 (N), HCO3 
– With respiratory compensation, CO2 may be 
• Respiratory acidosis - pH , CO2  HCO3 (N)
– With metabolic compensation, HCO3 may be 
• Respiratory alkalosis - pH , CO2 , HCO3 (N)
– With metabolic compensation, HCO3 may be 
Case studies
A 60 year old man was admitted with an
exacerbation of chronic obstructive
pulmonary disease. His arterial blood
gases on air showed:
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pH 7.29
PaCO2 8.5 kPa
Pao2 8.0 kPa
HCO3 30.5 mmol/l.
7.35-7.45
4.7-6.0
10-13
22-30
What is the acid-base disturbance and what is
the management?
• Respiratory Acidosis
– Type 2 failure
• Treatment is nebulisers/steroids/NIV
• A 45 year old lady with previous peptic ulcer
disease was admitted with persistent
vomiting. She looked dehydrated. Her blood
results were
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sodium 140 mmol/l
potassium 2.5 mmol/l
pH 7.5
Paco2 6.0 kPa
Pao2 14 kPa
HCO3 40 mmol/l.
135-145
3.5-5.5
7.35-7.45
4.7-6.0
10-13.0
22-30
What is the acid-base disturbance and why? How
would you treat this patient?
• This patient had alkalosis due to a high
standard bicarbonate-metabolic alkalosis.
The PaCO2 was appropriately low in
compensation. This was hypokalaemic
hypochloraemic metabolic acidosis because
of potassium and chloride loss from vomiting.
Treatment was of the underlying cause
(pyloric stenosis) and intravenous sodium
chloride with potassium.
• A 58 year old lady recently underwent a left
hemicolectomy for cancer. 4 days later she
complained of substernal abdominal pain,was
nauseous and sweaty. Her gases showed:
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pH 7.1
PCO2 - 3.5
PO2 - 18.3
HCO3 - 13
BE - -12
7.35 - 7.45
4.7 - 6.0
10 - 13.0
22 - 30
-2 - +2
• What would you do now? How would you
manage this lady?
Practice questions
• 79 year old man started on diuretics for
hypertension 2 weeks ago presents with
a seizure. Bloods:
– FBC, Ca2+ (N)
– U+Es
» Na 107
» K 3.1
» U 7.2
» Cr 122
• Diagnosis?
Hyponatraemia secondary to diuretic use
• 17 year old presents with confusion,
dehydration, fever. T39.5, HR 120, BP
100/50.
– Bloods
– FBC: Hb 13.0, WCC 19.2, Plt 180
– U+Es: Na 147, K 5.1, U 26.2, Cr 208
– Gluc: 34.9
Diagnosis?
Diabetic Ketoacidosis
• 47 year old lady presents with
abdominal pain. Lost 3 stones over 6
months. On examination she has a
palpable gallbladder. Bloods
• FBC - Hb 8.1, MCV 69, WCC 7.5
• U+Es - Na 135, K 3.4, U 7.2, Cr 145
• LFTs - Bili 190, ALP 360, ALT 55, GGT 450
Diagnosis?
Obstructive Jaundice likely secondary to malignancy
• 28 year old Nigerian man presents to
casualty jaundiced with vomiting,
diarrhoea. History of flu like symptoms 2
weeks previously.
– LFTs - bilirubin 43, ALP 96, ALT 1522, GGT
45. INR 1.2
Diagnosis?
Hepatitis A most likely
• 61 year old arteriopath presents having
recently been started on ACE inhibitors,
with confusion and pruritis.
– FBC normal
– U+Es - Na 130, K 7.4, Ur 37, Cr 841
Diagnosis?
Renal artery stenosis
• 35 year old presents with diarrhoea,
sweating and palpitations.
– FBC (N)
– U+E (N)
– TFTs: TSH 0.01, T4 250
Diagnosis?
Hyperthyroidism- Graves disease