OSCE data interpretation Flashcards
What is measured in thyroid function tests?
TSH
T3
T4
What is the ratio of T3 and T4 produced by the thyroid?
T4:T3 is 20:1
T3 is produced by peripheral conversion of T4
Free T4 makes up …….% of total T4, with the rest being bound to thyroid binding globulin.
1%
What clinical features are found in Grave’s disease?
Exophthalmos
Pretibial myxoedema
What will the TFTs be in hypothyroidism?
TSH high
T4 low
(if T4 is normal and TSH is raised, this suggests subclinical hypothyroidism)
What will the TFTs be in secondary hypothyroidism (pathology of pituitary or hypothalamus)?
TSH normal/low
T4 low
What will the TFTs be in Grave’s disease?
TSH low
T3 and T4 high
Why are LFTs ordered?
- Investigate suspected liver injury/disease
2. Distinguish between hepatocellular injury and cholestasis
Which blood tests are included in LFTs?
ALT AST ALP GGT Bilirubin Albumin Prothrombin time (PT)
What are the causes of an isolated rise in ALP?
- Bony metastases/ primary bone tumours eg. sarcoma
- Vitamin D deficiency
- Recent bone fracture
- Renal bone disease (CKD)
If a patient has dark urine and normal stools, what does this suggest about the cause of jaundice?
Hepatic jaundice
If a patient has dark urine and pale stools, what does this suggest about the cause of jaundice?
Post hepatic jaundice (obstructive)
What can cause LOW albumin levels?
- Liver disease
- Inflammation-> acute phase response
- Loss of albumin- nephrotic syndrome
If ALT>AST what does this sugguest?
Chronic liver disease
NAFLD
Drug/ viral hepatitis
If AST> ALT what does this suggest?
Alcoholic hepatitis
Cirrhosis
Cancer
What are common causes of ACUTE hepatocellular injury?
- Poisoning eg. paracetamol overdose
- Hepatitis A and B
- Liver ischemia
What are common causes of CHRONIC hepatocellular injury?
- Alcoholic fatty liver disease
- Non alcoholic fatty liver disease
- Chronic infection (Hepatitis B or C)
- Primary biliary cirrhosis
What are LESS common causes of CHRONIC hepatocellular injury?
- Alpha 1 antitrypsin deficiency
- Wilson’s disease
- Haemochromatosis
What does a typical liver screen involve?
- LFTs
- Coagulation screen
- Viruses- Hepatitis A/B/C, EBV, CMV
- Autoantibodies: AMA, pANCA, ANA, ASMA
- Immunoglobulins: IgM and IgG
- Alpha-1 antitrypsin
- Copper (Wilson’s disease)
- Ferritin (Haemochromatosis)
What blood tests will be done if a patient is confused (confusion screen)?
- FBC (WCC for infection)
- CRP
- U&Es (Uraemia/ hyponatraemia)
- Bone profile (hypercalcaemia/ hypocalcaemia)
- B12 and folate (deficiency)
- TFTs (hypothyroid)
- Glucose (hypogylcaemia)
- LFTs (hepatic encephalopathy)
- Coagulation/ INR
What clinical observations may suggest anaemia due to active bleeding?
Hypotension
Tachycardia
What lab tests should be done to investigate anaemia?
- FBC
- TFTs (hypothyroidism can cause macrocytic anaemia)
- U&Es (CKD can cause anaemia)
- Haematinics: B12, folate, ferritin, iron, TIBC
What blood tests should be done to investigate hyponatraemia?
- U&Es: asses degree of hyponatraemia/ renal function
- Serum/ urine osmolality
- TFTs (hypothyroidism can cause hyponatraemia)
- Serum cortisol (Addison’s)
What lab tests are done in a myeloma screen?
- FBC (anaemia/ neutropenia/ thrombocytopenia)
- U&Es (raised creatinine/ hypercalcaemia)
- ESR (raised)
- Blood film (RBCs stacked ontop of each other)
- Blood and urine protein electrophoresis (paraprotein band)
- Immunoglobulin measurement
- Bone marrow biopsy (increased number of plasma cells)
What imaging is done to screen for myeloma?
Xrays
MRI
look for lytic lesions of skull, axial skeleton, proximal long bones
What is the NORMAL appearance of CSF?
Clear
Colourless
What is a NORMAL CSF WBC count?
0-5cells/uL
NO neutrophils, only lymphocytes
What is a NORMAL CSF opening pressure?
10-20 cm H2O
What is the NORMAL glucose level in CSF?
2.8-4.2 mmol/l
What will the CSF findings be in bacterial meningitis?
- Cloudy and turbid appearance
- Increased opening pressure (>25 cm H2O)
- Increased WCC (>100cell/uL) mainly polynuclear lymphocytes
- Low glucose level
- Increased protein level
What will the CSF findings be in viral meningitis?
- Clear appearance (asceptic)
- Normal or increase opening pressure
- Increased WCC (50-1000cell/uL) mainly lymphocytes
- Normal glucose level
- Increased protein level
Which 3 organisms are the most common causes of bacterial meningitis in adults?
- Neisseria meningitidis
- Streptococcus pneumoniae
3 Listeria
Which 3 organisms are the most common causes of bacterial meningitis in children?
- Neisseria meningitidis
- Streptococcus pneumoniae
- Haemophilus influenzae
What will the CSF findings be in fungal meningitis?
- Clear or cloudy appearance
- Increased opening pressure (>25 cmH2O)
- Increased WCC (10-500cell/uL) mainly lymphocytes
- Low glucose level
- Increased protein level
Which 2 organisms are the main cause of fungal meningitis?
- Cryptococcus neoformans
2. Candida
What clinical signs/ symptoms are less common in fungal meningitis than bacterial meningitis?
- Fever
2. Neck stiffness
What will the CSF findings be in a sub arachnoid haemorrhage?
- Blood stained then yellow appearance
- Increased opening pressure
- Increased WCC
- Increased RBC
- Normal glucose
- Increased protein
What will the CSF findings be in GBS?
- Clear or yellow appearance
- Normal or increased opening pressure
- Normal WCC
- Normal glucose
- Increased protein
Coryzal symptoms are most common in which type of meningitis?
Viral
Neck stiffness is a common symptom in meningitis and which other condition?
Subarachnoid haemorrhage
What is the normal range for ABG PaCo2?
4.7 - 6 kPa
What is the normal range for ABG PaO2?
11- 13 kPa
What is the normal range for ABG HCO3-?
22-26 mEq/l
What is the normal range for ABG base excess?
-2 to +2 mmol/l
What is the likely cause of a very low PaO2 in a patient who looks completely well, is not short of breath and has normal O2 saturations?
Venous blood sample
What is the most important factor to look at first when analysing ABG results?
Is the patient hypoxic
Which value is hypoxia on an ABG?
<10kPa
What does a high base excess mean?
There is a HIGHER than normal amount of HCO3- in the blood
What does a low base excess mean?
There is a LOWER than normal amount of HCO3- in the blood
What acid base disturbances cause a high base excess?
Metbolic alkalosis
Compensated respiratory acidosis
What acid base disturbances cause a low base excess?
Metabolic acidosis
Compensated respiratory alkalosis
What are the causes of respiratory acidosis?
- Respiratory depression eg. opiates
- COPD
- Asthma
- Guillain-Barre syndrome
What are the causes of respiratory alkalosis?
- Anxiety
- Panic attack
- Pain
- PE
- Pneumothorax
- Hypoxia
What are the causes of a high anion gap metabolic acidosis?
MUDPILES M- Methanol U- Uraemia D- Diabetic /alcoholic/ starvation ketoacidosis P- Paracetamol overdose I- Isoniaid L- Lactic acidosis E- Ethanol S- Salicylates
What are the causes of a low anion gap metabolic acidosis?
- GI losses of bicarbonate: diarrhoea, ileostomy, proximal colostomy
- Renal tubular acidosis
- Addison’s disease
What are the causes of metabolic alkalosis?
- GI losses of acid: vomitting/diarrhoea
2. Renal loss of acid: Loop and thiazide diuretics, heart failure, nephrotic syndrome, cirrhosis, Conn’s syndrome
How would a mixed respiratory and metabolic acidosis appear on ABG?
pH LOW
CO2 HIGH
Bicarbonate LOW
How would a mixed respiratory and metabolic alkalosis appear on ABG?
pH HIGH
CO2 LOW
Bicarbonate HIGH
What factors need to be looked at to assess the image quality of a chest Xray? (RIPE)
R- ROTATION: the medial aspect of each clavicle equidistant from spinous processes, and the spinous processes should be vertically orientated against the vertebral bodies
I- INSPIRATION: 5-6 anterior ribs, lung apices, both costophrenic angles and lateral rib edges
P- PROJECTION: AP or PA (if no label/ scapulae not visible assume PA)
E- EXPOSURE: Vertebrae should be visible behind the heart
Where are the clavicles in a PA chest Xray?
Project OVER the lung fields
Where are the clavicles in an AP chest Xray?
Above the apex of the lung fields
Which ribs are distinct in a PA chest Xray?
Posterior ribs
Which ribs are distinct in an AP chest Xray?
Anterior ribs
What is the ABCDE approach to chest X ray interpretation?
A- AIRWAY: is the trachea deviated? Is the carina visible? Are hilar structures visible?
B- BREATHING: compare each lung zone. Are the pleura visible (shouldn’t be normally)? Do the lungs markings extend to the edges of the lung fields?
C: CARDIAC: what is the heart size? (normal is cardiothoracic ratio <0.5 in PA) Assess the heart borders
D: DIAPHRAGM: Is there free gas under the right side? (suggests bowel perforation) Are the costophrenic angles visible?
E: EVERYTHING ELSE: Mediastinal contours eg. aortic knuckle, Bones eg. fractures, soft tissues, tubes, valves, pacemakers.
REVIEW ALL AREAS: Apices, retrocardiac, behind the diaphragm, hilar, peripheral lungs
What tests are done to investigate a PE?
- Bloods: FBC, U and E, clotting, D-dimer
- ABG: Look for resp failure
- CXR: May be normal or dilated pulmonary artery
- ECG: May have tachycardia or RBBB
How should a PE be treated?
- If haemodynamically unstable, thrombolyse with alteplase IV
- If haemodynamically stable, give LMWH or heparin
Then give DOAC or warfarin
What are the Well’s criteria for a PE?
- Signs/ symptoms of a DVT
- Bedridden/ recent surgery
- Previous DVT/ PE
- Malignancy
- Other diagnosis less likely
- Haemoptysis
- HR >100
What are the potential causes of haemoptysis?
Lung causes:
- Infection
- Malignancy
- Bronchiectasis
- Goodpastures
- Sarcoidosis
Vascular causes:
1. PE
2. Vasculitis
3, Pulmonary hypertension
Cardiac causes:
1. Mitral stenosis
Which antibiotics are used to treat bacterial meningitis?
Cephalosporins
Which drugs are used to treat viral meningitis?
Aciclovir
Which drugs are used to treat fungal meningitis?
Fluconazole
What are the causes of a right bundle branch block?
- Isolated RBBB
- Ischemia
- RVH
- Cor pulmonale
- PE
- ASD
What are the causes of a left bundle branch block?
- Ischemia
- LVH
- Hypertension
- Cardiomyopathy
What are the causes of 3rd degree heart block?
- Digoxin toxicity
- Fibrosis
- Ischemia (Inferior MI)