In this post… Why drinking seawater causes dehydration Why giving 0.9% NaCl can exacerbate hyponatraemia in some circumstances How much water do you have to drink to cause hyponatraemia Why most patients on furosemide should also have restricted water intake Why a “tea and toast” diet causes hyponatraemia Why limiting dietary solute intake can help in nephrogenic diabetes insipidus Physicists may still be searching for the grand unified theory of everything, but nephrologists have come pretty close to a unified theory of urine.

In this post… The paradoxical anti-diuretic effects of diuretics A general approach to nephrogenic diabetes insipidus When is a tractor not a tractor? … When it turns into a field Nephrogenic diabetes insipidus Nephrologists are often asked for advice on how to manage patients with nephrogenic diabetes insipidus (NDI). Almost always, this has been caused by current or historic lithium exposure. This is one of those referrals that invariably sends me scuttling back to review original literature, because I can never quite remember how on earth diuretics are supposed to magically transform into anti-diuretics in this context, nor the relative merits of thiazides / amiloride / acetazolamide.

In this post… What effect do loop diuretics have on renal free water clearance? Should we stop furosemide in hyponatraemia? Why do we need to restrict water intake when giving furosemide in hyponatraemia? We are mostly water and rapidly run into trouble when we become under- or over-hydrated. We could argue, therefore, that one of the kidney’s most important jobs is that of maintaining water homeostasis. It is surprising that we are able to mess around quite profoundly with this process without running into trouble more frequently than we do.

In this post… The evolution of the vasopressin system How can one hormone regulate two physiological parameters (tonicity and blood pressure)? Why does terlipressin not always cause profound hyponatraemia? “Thousands have lived without love, not one without water.” — WH Auden Does terlipressin cause hyponatraemia? We had a patient with hepatorenal syndrome on the unit recently. Her sodium was 125 mM and I found myself wondering - as I always do in such a patient - whether terlipressin could be contributing.