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NBME 24 Answers

nbme24/Block 2/Question#6 (26.5 difficulty score)
A 50-year-old woman is admitted to the ...
Factitious disorder🔍

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submitted by seagull(1112),
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ihsT is a enic phpcoara ot yntdiiegfin dan iartnget iiaftotsuc .erdsrodi


cinnapie  Not all heros wear capes +  
privwill  Mother of mine strongly believes in this method of treatment... +6  
aisel1787  lmao +  

acute exacerbation of CHF leads to reduced CO --> hypervolemic hyponatremia, body perceives it as hypovolemic (so you expect high ADH) ["non-osmotic release of ADH"]

  • this pt is clinically hypervolemic (edema, rales, distended neck veins)

  • urine should be concentrated (UOsm >100 mOsm/kg) because kidneys should be fine and ADH is doing its job, just with bad information

  • if urine is dilute, it's not CHF, it's psychogenic (can be caused by schizophrenia or factitious disorder)

let's say she wasn't crazy and really was having CHF exacerbation - tx with diuretic and fluid restriction as they did--> note that you can also use vaptan drugs for CHF-related hyponatremic hypervolemia (block ADH) --> should cause the urine to be dilute which will reduce the hypervolemia and reduce salt resorption to correct the hyponatremia

random diabetes inspidius side note for psychogenic polydipsia (DI dx is hypernatremia/normal, hypovolemia, dilute urine <100mOsm/kg)

  • can also use the water deprivation test for a pt with polyuria and polydipsia

--> if urine concentrates, it's psychogenic

--> if it does not concentrate, give desmopressin and if it concentrates = central DI, does not concentrae = nephrogenic DI

How does one differentiate factitious disorder from being thirsty w poor impulse control?

therealslimshady  If you're asking how to rule out diabetes insipidus, I think it's because: Diabetes insipidus is caused by a lack of ADH effect, so they will be peeing out too much water, thus making them dehydrated and hyperosmolar (thirsty). This CHF patient is presenting with signs of fluid overload +1