2025 – PAGE 374 – FLUIDS & ELECTROLYTES

HYPOKALEMIA

Hypokalemia can result in constipation, lethargy, and weakness. May be caused by losses of potassium in stool or emesis. If there is hypomagnesemia, REPLACE THE MAG!

• PEARL: If you see a patient with hypokalemia and hypomagnesemia, have a high suspicion for renal dysfunction, such as acute tubular necrosis due to cisplatin/platinum drugs. Also, just because hypomagnesemia is present, it does NOT mean that hypokalemia will be present. BUT if both are present, your potassium will not rise until the magnesium is replaced.
• LOW-YIELD/GUNNER FACTS: Can result in premature ventricular complexes, T-wave flattening, U waves, (opposite of hyperkalemia), and possible ST segment depressions.

HYPERKALEMIA

Hyperkalemia is much more serious than hypokalemia and can potentially cause SUDDEN DEATH due to arrhythmias. Look for peaked T-waves on an EKG. Treat with calcium (calcium chloride or calcium gluconate) to immediately limit the chances of lethal arrhythmias. Also give either a loop diuretic (furosemide, bumetanide) and/or sodium polystyrene (oral or rectally). As a temporizing measure only, you can give insulin to shove the potassium into cells, but DON’T forget to also give glucose to prevent hypoglycemia. If all else fails, or the patient has extreme symptoms (weakness, arrhythmias), dialyze. Potential causes are listed below. Management is more important.

• RHABDOMYOLYSIS: Look for elevated CK level, POSITIVE BLOOD on the urine dipstick with NO or few RBCs on urine microscopy. It’s actually MYOGLOBIN that gives the false positive. As cells lyse, intracellular potassium is released and hyperkalemia ensues. Calcium deposits into muscles; assume that’s why you can also get hypo Treat with aggressive hydration and possibly sodium bicarbonate to alkalinize the urine.
• RENAL FAILURE: Dialyze
• POTASSIUM SPARING DIURETICS: Includes spironolactone and triamterene. Never give with an ACE inhibitor. Low-yield topic.
• ALDOSTERONE DEFICIENCY: This can be a primary disorder (renal diseases resulting in hyporeninemia) or due to ADDISON’S D Aldosterone helps retain sodium and excrete potassium. When absent, the classic picture of HYPERKALEMIA + HYPONATREMIA occurs. Any time you see that combination on a chemistry panel, have a HIGH suspicion that there is an aldosterone problem.
• METABOLIC ACIDOSIS: Assume it’s because the extra hydrogen ions are going into the cells and potassium is coming out to maintain neutrality.
• BURNS: From cell lysis.
• MASSIVE BLOOD TRANSFUSIONS: From cell lysis.
• RTA IV: Low-yield