29 year old female with history of Sjogren's syndrome presents with a 2 day episode of watery diarrhea 2 days ago. Physical examination is unremarkable. Because of her history, the physician decides to check her urine electrolytes. Urine chemistry: K = 31, Na = 100, Cl = 105. Her current diagnosis is?
High-Yield Explanation
* The urine electrolytes are used to distinguish between A and diarrhea * UAG is an indirect measure of ammonium excretion * UAG = (Na + K) - Cl * UAG = ( 100 + 31 ) - 105 = 26 * A positive UAG suggest A because in the setting of diarrhea, ammonium chloride concentration in the urine would be high and the UAG would be negative. * A positive value suggests that the kidney is unable to adequately excrete ammonium, leading to a reduction in net acid excretion and thus metabolic acidosis. Hyperkalemia, acidemia is seen in type IV A Type IV A associated with Diabetes Mellitus