1. © Dr Karan Wadhwa & Dr Tim Coughlin
Blood Tests & ABGs
© Dr Karan Wadhwa & Dr Tim Coughlin

2. Objectives
Discuss
basic blood tests
ABGs
Use some case examples and practice some sample questions
Questions

3. Why?

4. Why do blood tests? Haematinics Nutritional status
Exposure to toxic substances
Markers of infection
Hydration status
Renal function
Baseline before treatment
Etc…

5. 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

6. Others Troponin I Calcium/magnesium/phosphate Glucose Amylase
Clotting/INR/APTT

7. Patterns in disease Infective process e.g. Strep Pneumonia Anaemia
WCC - neutrophillia
CRP
Anaemia
Macrocytic - High MCV
Microcytic - Low MCV
Normocytic - Normal MCV

8. Renal dysfunction/dehydration
Urea
Creatinine
Sodium
Poor nutrition
Albumin/Protein

9. Liver function Thyroid disease Clotting Jaundice
Prehepatic - conjugated bilirubin, Coombs
Hepatic - ALT
Post hepatic - ALP/GGT
Thyroid disease
Hyperthyroidism - Low TSH, High T4
Hypothyroidism - High TSH, Low T4

10. Arterial Blood Gases Procedure Results pH 7.35 - 7.45
PCO kPa PO
HCO
Base excess
A low HCO3- or negative base excess indicates metabolic acidosis, a high HCO3- or high positive base excess, metabolic alkalosis.

11. Logic behind blood gases

12. 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 

13. Case studies A 60 year old man was admitted with an
exacerbation of chronic obstructive
pulmonary disease. His arterial blood
gases on air showed: pH
PaCO2 8.5 kPa
Pao2 8.0 kPa
HCO mmol/l
What is the acid-base disturbance and what is the management?

14. Treatment is nebulisers/steroids/NIV
Respiratory Acidosis
Type 2 failure
Treatment is nebulisers/steroids/NIV

15. A 45 year old lady with previous peptic ulcer disease was admitted with persistent vomiting. She looked dehydrated. Her blood results were
sodium 140 mmol/l
potassium 2.5 mmol/l pH
Paco2 6.0 kPa
Pao2 14 kPa
HCO3 40 mmol/l
What is the acid-base disturbance and why? How
would you treat this patient?

16. 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.

17. What would you do now? How would you manage this lady?
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: pH
PCO PO
HCO BE
What would you do now? How would you manage this lady?

19. 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

20. 17 year old presents with confusion, dehydration, fever. T39
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

21. 47 year old lady presents with abdominal pain
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

22. 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

23. 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

24. 35 year old presents with diarrhoea, sweating and palpitations.
FBC (N)
U+E (N)
TFTs: TSH 0.01, T4 250
Diagnosis?
Hyperthyroidism- Graves disease