Ratio Profile: Physiologic Approach to Estimating Appropriate Intravenous Fluid Rate to Manage Hyponatremia in the Syndrome of Inappropriate Antidiuresis.

A hyponatremic patient with the syndrome of inappropriate antidiuresis (SIAD) gets normal saline (NS), and the plasma sodium decreases, paradoxically. To explain, desalination is often invoked: if urine is more concentrated than NS, the fluid's salts are excreted while some water is reabsorbed, exacerbating hyponatremia. But comparing concentrations can be deceiving.

Improving on the Adrogué-Madias Formula.

The Adrogué-Madias (A-M) formula is correct as written, but technically, it only works when adding 1 L of an intravenous (IV) fluid. For all other volumes, the A-M algorithm gives an approximate answer, one that diverges further from the truth as the IV volume is increased. If 1 L of an IV fluid is calculated to change the serum sodium by some amount, then it was long assumed that giving a fraction of the liter would change the serum sodium by a proportional amount.

Recurrent calcium nephrolithiasis associated with primary aldosteronism.

Typical manifestations of hyperaldosteronism include salt retention, hypokalemia, and metabolic alkalosis. However, a consequence infrequently recognized and described is hypocitraturia. In combination with hypercalciuria, aldosterone-induced hypocitraturia can trigger calcium nephrolithiasis.