Not All Hyponatremia Is Real — The Osmolality-First Approach

When a sodium comes back at 118, the instinct is to treat. But before anyone touches that IV line, there's one question you need to answer first — is this real hyponatremia?In this episode, we build the osmolality-first framework from the ground up. We cover how hospital labs actually measure sodium, why the indirect ion-selective electrode can be fooled, and how the serum osmolality catches the error every time.Along the way, we work through five clinical cases: pseudohyponatremia from lipoprotein X in cholestatic liver disease, occult multiple myeloma unmasked by a blood gas discrepancy, IVIG-induced pseudohyponatremia in Guillain-Barré syndrome, severe hypertriglyceridemia mimicking hypovolemic hyponatremia, and translocational hyponatremia after kidney transplant and hysteroscopy.By the end, you'll have a three-step framework you can use at the bedside every time you see a low sodium — before you order a single treatment.Next episode: SIADH — causes, mimics, and when to reach for 3% saline versus fluid restriction versus urea.