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© Dr Karan Wadhwa & Dr Tim Coughlin
Blood Tests & ABGs © Dr Karan Wadhwa & Dr Tim Coughlin
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Objectives Discuss basic blood tests ABGs Use some case examples and practice some sample questions Questions
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Why?
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Why do blood tests? Haematinics Nutritional status
Exposure to toxic substances Markers of infection Hydration status Renal function Baseline before treatment Etc…
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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
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Others Troponin I Calcium/magnesium/phosphate Glucose Amylase
Clotting/INR/APTT
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Patterns in disease Infective process e.g. Strep Pneumonia Anaemia
WCC - neutrophillia CRP Anaemia Macrocytic - High MCV Microcytic - Low MCV Normocytic - Normal MCV
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Renal dysfunction/dehydration
Urea Creatinine Sodium Poor nutrition Albumin/Protein
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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
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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.
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Logic behind blood gases
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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
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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?
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Treatment is nebulisers/steroids/NIV
Respiratory Acidosis Type 2 failure Treatment is nebulisers/steroids/NIV
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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?
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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.
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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?
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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
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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
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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
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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
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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
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35 year old presents with diarrhoea, sweating and palpitations.
FBC (N) U+E (N) TFTs: TSH 0.01, T4 250 Diagnosis? Hyperthyroidism- Graves disease
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