Oxford Handbook of Clinical and Laboratory Investigation (Oxford Handbooks Series)
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Modern medicine is highly complex and investigations are a key part of the diagnostic process. With major advances in technology there are thousands of clinical and laboratory tests available. The 'Oxford Handbook of Clinical & Laboratory Investigation' provides a patient-oriented approach to investigation where key symptoms and signs are described along with tests that may be of value in reaching a diagnosis. The remainder of the Handbook is specialty-centered and provides a comprehensive review of all available tests within a given subject. Contributors are all active clinicians who are engaged in medical practice, who appreciate the problems faced by junior doctors. The Handbook should also be of value to senior medical students, and who will soon be on the wards and responsible for ordering tests on their patients.
produces 4 IgM), 44WBC in leukaemia. Investigations 2 FBC and film. 2 Coagulation—INR and APTR . 2 Bleeding time, measures platelet and vascular phase. 2 DIC screen including fibrinogen, thrombin time, D-dimers or FDP s. Consider further tests and referral to haematology for 2 Factor assays. 2 Platelet aggregation studies to assess platelet function. OHCM p646. Calf swelling Assess whether swelling is bilateral or unilateral, precipitating factors and duration of onset. Careful examination of
ECG . 2 CXR . 2 Cardiac enzymes. 2 Troponin T or I . 2 Exercise tolerance test. 2 Coronary angiogram. 2 Myoview scan. 2 D-dimers. 2 V/Q scan. 2 Leg doppler scan. 2 ABG s. 2 CT thorax. 2 Pulmonary angiogram. 2 Sputum culture (iacid and alcohol fast bacilli, AAFB ). 2 Sputum cytology. 2 Bronchoscopy. 2 FBC (anaemia may precipitate or aggravate angina). 2 Thoracoscopy. 2 Pleural tap. 2 Pleural biopsy. 2 Cervical spine x-ray. 2 Upper GI endoscopy. 21 02OHCI-01(1-96) 2 2 2 8/16/02 10:04 AM Page
thrombocytopenic purpura (ITP) may be 1° or 2° (e.g. lymphoma, lupus, HIV). Drugs (e.g. heparin) and blood transfusion (post-transfusion purpura) may cause severe thrombocytopenia. Investigations 2 FBC , film: – Inherited causes may be associated with giant platelets. – Morphological abnormalities may suggest MDS. – Red cell fragments suggest thrombotic microangiopathies, e.g. TTP. 2 LDH (4 in TTP and lymphoproliferative disorders). 2 Serum vitamin B12, folate (megaloblastic anaemia can be
ammonorrhoea—very suggestive. Other clues, loss of body hair (especially axilliary), reduced shaving, hyponatraemia, growth failure in children. Diabetes insipidus is not a feature as ADH can be secreted directly from the hypothalamus. Also signs of space-occupying lesion: bitemporal hemianopia (rarely optic nerve compression, homonymous hemianopia), headache (esp. following apoplexy), III, IV, V1, V2 or VI cranial nerve lesions, CSF rhinorrhoea. Occasionally galactorrheoa following pituitary
glycosuria’). Children are particularly liable to test positive for glucose. The renal threshold is effectively lowered in pregnancy. Conversely, a high threshold, common among the elderly, may give a misleadingly reassuring impression of satisfactory control. Fluid intake and urine concentration may affect glycosuria. Renal impairment may elevate the threshold for glucose reabsorption. 2 Delayed bladder emptying, e.g. due to diabetic autonomic neuropathy ( OHCM section 9), will reduce the