Second line investigations in selected stroke patients
| Investigation | Indications | Disorders suggested |
| Liver function tests | Fever, malaise, raised erythrocyte, ESR, malignancy | Giant cell arteritis, infective and non-bacterial thrombotic endocarditis |
| Calcium | Hypercalcaemia may rarely cause recurrent focal symptoms | Hypercalcaemia |
| Activated partial thromboplastin time, dilute Russell's viper venom time, anticardiolipin antibody, antinuclear and other antibodies | Young patient, previous or family history of venous thrombosis, recurrent miscarriages, thrombocytopenia, cardiac valve vegetations, livedo reticularis, raised ESR, malaise, positive VDRL | Antiphospholipid antibody syndrome, systemic vasculitis, systemic lupus erythematosus |
| Protein C and S, antithrombin III, activated protein C resistance, thrombin time | Previous or family history of thrombosis (usually venous) of young onset | Deficiency states |
| Serum proteins and electrophoresis, plasma viscosity | Raised ESR | Paraproteinaemias, nephrotic syndrome, cardiac myxoma |
| Haemoglobin electrophoresis | AfroCaribbean patients | Sickle cell trait or disease, other haemoglobinopathies |
| Blood cultures | Fever, cardiac murmur, haematuria, deranged LFTs, raised ESR, malaise | Infective endocarditis |
| VDRL, HIV serology | Young, unexplained or “at risk” | Neurosyphilis, AIDS |
| Serum homocysteine, urinary amino acids | Marfanoid habitus, high myopia, dislocated lenses, osteoporosis, mental retardation, young | Homocystinuria |
| Leucocyte α-galactosidase A | Corneal opacities, cutaneous angiokeratomas, paraesthesias and pain, renal failure | Fabry's disease |
| Blood/CSF lactate, mitochondrial DNA analysis | Young, basal ganglia calcification, epilepsy, parieto-occipital ischaemia, migraine | MELAS/mitochondrial cytopathy |
| Drug screen (blood or urine) | “At risk” patient, no other cause | Drug induced stroke (amphetamine, cocaine, etc) |
| Chest radiography | Hypertension, finger clubbing, cardiac murmur or abnormal ECG, young | Calcified valves, enlarged heart, pulmonary AVM |
| Carotid ultrasound/MR angiography | Carotid distribution stroke in patient suitable for surgery | Cervical internal carotid stenosis |
| Cerebral angiography (intra-arterial digital subtraction or MR) | Young unexplained stroke, especially associated with pain or trauma, suspected arteritis, AVM or aneurysm | Arterial dissection, vascular abnormality |
| Transthoracic echocardiography | Suspected cardioembolism | Cardioembolism |
| Transoesophageal echocardiography | Suspected cardioembolism when TTE negative (eg endocarditis, atrial septal aneurysm), aortic dissection or atheroma, patent foramen ovale | Cardioembolism, aortic dissection or atheroma, paradoxical embolism |
| 24 hour ECG | Palpitations, suspicious resting ECG, clinical suspicion | Intermittent AF, heart block |
| Temporal artery biopsy | Older (>60), jaw claudication, headache, polymyalgia, malaise, anaemia, raised ESR | Giant cell arteritis |
ESR=erythrocyte sedimentation rate; VDRL=venereal disease research laboratory test; AVM=arteriovenous malfunction; LFT=liver function test; TTE=transthoracic echocardiography; AF=atrial fibrillation.