A book for clinicians and basic scientists
The pathophysiology of sodium is central to the management of a wide range of clinical conditions, notably liver disease, renal disease, cardiac failure, hypertension (including hypertension in pregnancy), oedema, diarrhoea, hypovolaemia, shock, the behavioural effects of hyper- or hyponatraemia and various endocrine disorders. Intensive care and fluid therapy depend crucially on sound management of sodium balance. No single clinical discovery has saved more lives at less cost than the fact that the fundamental impact of diarrhoea rests on disturbances of enteric sodium balance: the ability to restore net uptake by oral rehydration has converted cholera from a killer to a home-nursing disease. Yet if we look at animals, as well as humans, we realise that the gut is not just a source of sodium disturbances but, perhaps, a major regulator of sodium balance. We also realise that unless humans have some defect in their renal function, their routine exposure to salt is not only exorbitant but beyond their control and, arguably, pathological. The classic model animal for hypertension is the dog yet evidence suggests that the real interest in dogs lies less in their ability to model hypertension than their inherent resistance to it. This book emphasises the limitations and pitfalls, as well as the benefits of across-species extrapolation. In addition, a growing range of diseases, hitherto seeming to be unrelated, are linked by the underlying involvement of abnormalities of sodium handling: these include such disparate conditions as osteoporosis, cystic fibrosis, urolithiasis and gastric cancer. The book also discusses drugs intended to alter sodium balance, drugs whose mode of action depends on sodium transport and the interactions with electrolyte physiology which underlie the effects of these and many other drugs. It should enable clinicians better to understand the rationale behind their clinical routines and, perhaps more importantly7, provide the flexibility to recognise the need for change.