Background Definition Pathological: Inflammation of lung parenchyma distal to the terminal bronchioles, which includes the respiratory bronchioles, alveolar ducts, and alveoli. Clinical: Lower respiratory tract symptoms AND... {Focal chest signs (e.g. crackles) plus systemic signs (e.g. fever)} OR {unexplained CXR shadowing}. Chest infection: A non-specific term for lower respiratory tract infections, though tends to be used for milder presentations – i.e. acute bronchitis – rather than pneumonia. Acute bronchitis may or may not feature productive cough and fever, but has no focal chest signs and CXR is clear. Unlike pneumonia, antibiotics are not routinely indicated and only provide minimal symptomatic relief. Types Community-acquired pneumonia (CAP) Causes (% of all cases): Common bacteria: Strep. pneumoniae (50%) and H. influenzae (7%). Other bacteria: Staph. aureus (2%), Moraxella catarrhalis (2%), and the 'atypicals', Chlamydoph...
Background Pathophysiology Failure of antidiuretic hormone (ADH) – either central (ADH deficiency) or nephrogenic (ADH resistance) – leading to polyuria with dilute urine. Normal serum Na + often maintained through ↑fluid intake, and condition may be unmasked when fluids are restricted. Causes Central DI: Tumours – craniopharyngioma, stalk lesion, metastases – or pituitary tumour surgery. Acute trauma, subarachnoid haemorrhage. Inflammatory: CNS infection or autoimmune damage, the latter often associated with Hashimoto's thyroiditis or T1 diabetes. Infiltration: histiocytosis, sarcoidosis. Congenital: Wolfram syndrome (aka DIDMOAD) Phenytoin Nephrogenic DI: Altered electrolytes: ↑Ca 2+ ,↓K + . Medication: lithium, demeclocycline. Congenital: AVP-V2 mutation. Secondary to other conditions: sickle cell, sarcoidosis, amyloidosis, myeloma. Gestational DI: Can occur during pregnancy and postpartum period. Signs and symptoms Polyuria and nocturia. Polydipsia, which may be severe, and de...