MRCP(UK) Part 1 key terms

An exaggerated fall in systolic blood pressure of more than 10 mmHg during inspiration, detected with a blood pressure cuff. It occurs in cardiac tamponade, severe asthma and constrictive pericarditis.

Splitting of the second heart sound that widens on expiration and narrows or disappears on inspiration, the reverse of normal. It reflects delayed closure of the aortic valve, typically from left bundle branch block or severe aortic stenosis.

A paradoxical rise in jugular venous pressure on inspiration instead of the normal fall. It suggests impaired right ventricular filling and is classically seen in constrictive pericarditis, restrictive cardiomyopathy and right ventricular infarction.

Hypoxaemia with hypercapnia, usually defined as arterial oxygen tension below 8 kPa together with carbon dioxide tension above 6 kPa. It results from alveolar hypoventilation and occurs in COPD, neuromuscular disease and obesity hypoventilation.

The rate at which carbon monoxide diffuses from alveolar gas into blood during a single breath, expressed as a percentage of predicted. It is low in emphysema, pulmonary fibrosis and anaemia, and raised in asthma and pulmonary haemorrhage.

A three-part rule for classifying pleural fluid as an exudate: pleural to serum protein ratio above 0.5, pleural to serum lactate dehydrogenase ratio above 0.6, or pleural lactate dehydrogenase above two-thirds the upper limit of normal serum values.

A five-item score (confusion, urea above 7 mmol/L, respiratory rate 30 or more, low blood pressure, age 65 or over) that estimates mortality in community-acquired pneumonia and helps decide whether to treat at home or in hospital.

Serum albumin minus ascitic fluid albumin, measured in g/L. A gradient of 11 g/L or more indicates portal hypertension such as cirrhosis, while a lower value suggests a non-portal cause such as peritoneal malignancy or tuberculosis.

A scoring system using bilirubin, albumin, prothrombin time or INR, ascites and encephalopathy to grade the severity of cirrhosis as A, B or C and to estimate prognosis.

A score calculated from bilirubin, creatinine and INR, used to rank patients with cirrhosis for liver transplantation and to predict short-term mortality. Sodium is sometimes added to refine the estimate.

An autoantibody used to screen for coeliac disease while the patient is still eating gluten. It is sensitive and specific, but IgA deficiency can cause a false negative, so total IgA should be checked.

Glycated haemoglobin reflecting average blood glucose over the preceding two to three months. It is used to diagnose and monitor diabetes but is unreliable in haemoglobinopathies, recent transfusion, pregnancy and chronic kidney disease.

Serum calcium adjusted for the albumin concentration, since roughly half of circulating calcium is protein-bound. A common formula adds 0.02 mmol/L to measured calcium for every 1 g/L that albumin lies below 40 g/L.

A fragment released when proinsulin is cleaved to form insulin, so its concentration mirrors endogenous insulin secretion. It is low in type 1 diabetes and helps distinguish type 1 from type 2 diabetes and from factitious insulin use.

Abnormal thyroid function tests occurring during non-thyroidal illness, typically with low T3 and sometimes low TSH or T4. Values usually normalise after recovery, so routine thyroid hormone replacement is not indicated.

Serum sodium minus the sum of chloride and bicarbonate, normally about 8 to 16 mmol/L depending on the assay. A raised gap indicates accumulation of unmeasured anions such as lactate, ketones, urea or toxins.

The percentage of filtered sodium that is excreted in urine, calculated from paired serum and urine sodium and creatinine. A value below 1% suggests pre-renal hypoperfusion, though it is unreliable with diuretics and chronic kidney disease.

Protein excretion above 3.5 g per 24 hours, or a urine protein to creatinine ratio above about 350 mg/mmol. It causes hypoalbuminaemia, oedema and hyperlipidaemia, and predisposes to venous thrombosis and infection.

Features of a corticospinal tract lesion above the anterior horn cell: spasticity, increased tendon reflexes, extensor plantar responses and weakness with little muscle wasting. They contrast with the flaccid weakness and fasciculation of lower motor neuron lesions.

Failure of adduction in the eye on the side of a medial longitudinal fasciculus lesion, with nystagmus in the abducting eye on lateral gaze. Causes include multiple sclerosis in younger patients and brainstem infarction in older patients.

A score from 3 to 15 combining eye opening, verbal response and best motor response, used to grade level of consciousness after head injury and in other acute illness. A score of 8 or less usually prompts airway protection.

A test in which the patient stands with feet together and eyes closed; significant swaying indicates defective proprioception, as in sensory neuropathy or dorsal column disease. It is not a test of cerebellar function.

An antibody found in a majority of people with rheumatoid arthritis, often years before symptoms appear. It is more specific than rheumatoid factor and predicts more erosive joint disease.

An antibody directed against components of the cell nucleus, positive in systemic lupus erythematosus and many other autoimmune conditions but also in a proportion of healthy people, so results must be interpreted alongside the clinical picture.

Diffuse swelling of a whole digit, giving a sausage-like appearance. It occurs in psoriatic arthritis, reactive arthritis and other spondyloarthropathies, and also in sickle cell disease and tuberculosis.

The average volume of red blood cells, used to classify anaemia as microcytic, normocytic or macrocytic and so narrow the differential diagnosis. It also rises with alcohol excess and falls in thalassaemia.

A test that detects antibody or complement bound to the surface of red cells using anti-human globulin. A positive result supports immune-mediated haemolysis, such as autoimmune haemolytic anaemia or haemolytic disease of the newborn.

The proportion of circulating red cells that are young, newly released from marrow. A raised count indicates increased marrow output in response to haemolysis or blood loss, while a low count in anaemia suggests marrow failure or deficiency.

The interval between exposure to an infectious agent and the appearance of the first symptoms or signs. It helps determine quarantine and post-exposure prophylaxis and can distinguish infections that share clinical features.

An infectious or other disease that doctors are legally required to report to public health authorities, allowing surveillance and outbreak control. UK examples include measles, tuberculosis and meningococcal disease.

A coordinated programme to improve antibiotic prescribing: using the right drug, dose, route and duration, avoiding unnecessary antibiotics and reviewing treatment promptly, in order to limit resistance and adverse effects.

The apparent volume in which a drug would need to be distributed to produce its observed plasma concentration, calculated as dose divided by concentration. It is large for lipophilic drugs and small for drugs confined to plasma.

The time taken for the plasma concentration of a drug to fall by half during elimination. It determines how often a drug is dosed and how long it takes to reach steady state, usually about four to five half-lives.

Elimination at a constant rate that does not depend on drug concentration, so a fixed amount is removed per unit time. This occurs when enzymes are saturated, as with phenytoin, ethanol and high-dose aspirin, so small dose increases can cause toxicity.

Separation of the epidermis from the dermis when sliding pressure is applied to apparently normal skin, leaving a raw area. It is positive in pemphigus vulgaris, toxic epidermal necrolysis and staphylococcal scalded skin syndrome.

The appearance of new skin lesions along a line of injury or scratching in previously unaffected skin. It is seen in psoriasis, lichen planus and vitiligo, among other conditions.

Pinpoint bleeding that occurs when the scale of a psoriatic plaque is removed, reflecting elongation of the dermal papillae. It supports a diagnosis of psoriasis but is not present in every case.

An acute, fluctuating disturbance of attention and awareness, often with disorientation and disturbed sleep, caused by underlying illness, drugs, pain or the hospital environment. It is common in older people and is often mistaken for dementia.

A state of reduced physiological reserve that makes a person vulnerable to minor stressors, recognised by weight loss, exhaustion, slow gait, low activity and weakness. It predicts falls, hospital admission and death, and guides treatment goals.

A multidisciplinary process that assesses the medical, psychological, functional and social needs of an older person and then produces a coordinated care plan. It improves survival and the chance of remaining at home after admission.