Question of the Week # 20, 21

A 26 year old woman presents to the ER with generalized weakness associated with perioral numbness. She is moderately built and looks slightly depressed. On physical exam, she has mild pallor. She denies use of any medications. BP 120/88 mmHg and physical exam is normal. Lab data: Cr 1.2mg/dL, BUN 15mg/dLNa 136 , K 2.8 , Cl 88 , HCO3 38. Urine Na  45 meq/L, Urine K   35 meq/L, Urine Cl   8 meq/L, Urine specific gravity 1.010, Urine pH 7. 

Most likely diagnosis is :

A)Laxative Abuse

 B)Surreptious vomiting

 C)Licorice abuse

D)Malabsorption Syndrome

 E)Hyporeninemic Hypoaldosteronism

q21) Most appropriate next step in the management:

A)IV normal saline



D)Psychiatry consult

 E)Reassurance because this is self limiting beca


24 Responses

  1. bd

  2. B Surreptious vomiting metabolic alkalosis


  3. B, D

  4. b,d

  5. e a

  6. B

  7. B

  8. BD

  9. bbb?

  10. HA HAAA

  11. The patient has metabolic alkalosis which is mostly saline responsive.
    In Dr.Red’s lecture, Met alkalosis has been divided in to two types : saline responsive and saline resistant.
    Contraction metabolic alkalosis that is secondary hypovolemia will always respond to NS.
    Normally, we check urine Na+ Level to see if there is hypovolemia. If urine NA+ is less than 10 it is more consistent with hypovolemia. However, metabolic alkalosis
    spuriously increases Urine NA+ level. Therefore, urine NA+ is not a reliable predictor for volume status in met.alkalosis. Hence, urine chloride is the most important result here and a urine chloride < 10 suggest hypovolemia here. Once you know that urine cl- is low, next step is to give NS to correct this hypovolemia induced metabolic alkalosis.

    • How do you explain the blood pressure of 120/88 mm hg on the basis of your urine chloride being low? How can a hypovolemic severely dehydrated patient with a urine cl level of less than 8 have a normal blood pressure? The perioral numbness is due to the hypokalemia. She needs to get aggressive rehydration with K+ supplements and not normal saline! 😉

  12. The answer is B and D

    When potassium is low and there is no other medical explanation, it is almost certain that the patient is either vomiting or abusing laxatives or diuretics.

    Purging also throws the body’s acid-base balance off-kilter, which is reflected in another type of electrolyte disturbance, elevated bicarbonate levels in the blood. These laboratory values of low potassium and elevated bicarbonate levels could, to the unsuspecting or inexperienced doctor, incorrectly indicate a kidney problem, not surreptitious vomiting.

    Although elevated serum bicarbonate is not as serious as the low potassium that can accompany purging behaviors, it is something that can be tested for, and is a much more reliable marker than potassium for purging behaviors. For this reason, some doctors order a serum bicarbonate test when they suspect purging, even though potassium levels are normal.

  13. Ans. B
    Ans. A

    Key concepts : Recognize the etiologies of metabolic alkalosis. Understand the concept of urinary chloride level in identifying the etiology of metabolic alkalosis. If urinary chloride is less than 10meq/L, it indicates Saline responsive alkalosis. A higher than 10 value indicates Saline resistant alkalosis.

    Ans. B is the correct choice because the patient has hypokalemic, hypocholremic metabolic alkalosis. Urinary chloride less than 10 indicate that this is a saline responsive metabolic alkalosis and hence, should be treated with IV normal saline. NS can correct this metabolic alkalosis.

    Ans. A incorrect because diarrhea due to laxative abuse should cause non anion gap metabolic acidosis.

    Ans. C is incorrect. The active component in licorice is glycyrrhizic acid which inhibits 11B-HSD2, the enzyme that inactivates cortisol to cortisone in the collecting duct. Inhibition or deficiency of 11B-HSD2 causes cortisol to remain active and like aldosterone, cortisol binds to aldosterone receptors causing hypokalemia, metabolic alkalosis and low-renin and low-aldosterone hypertension. This is not licorice abuse because this patient does not have hypertension. Also, urinary chloride will be higher than 10 in licorice induced metabolic alkalosis

    Ans. D is incorrect because it should cause chronic diarrhea and non-gap metabolic alkalosis.

    Ans. E is incorrect because hyporeninemic hypoaldosteronism causes hyperkalemia and metabolic acidosis
    ( Type IV RTA)

    • If she is sureptous vomiting, you will need to correct the electrolytes b/c there is danger of her getting cardiac,seizueres, or any life threatening situation. This is an emergency! Treat!

      • chill out, this is not emergency. just give saline+kcl and check lytes in 1hr after fluids.

  14. ..official archer answer?

  15. A
    A…official answer in Dr red answersheet…. dont know how

  16. C and b

  17. Lots of suggestions. Can I please have a definitive review on this?

  18. My suggestion is why give intravenous fluids when patient is homeostatically stable. Psychiatric consult for a patient with diagnosed Surreptitious vomiting should be a better approach

  19. B

    Surreptitious vomiting causes secondary hyperaldosteronism which maintains blood pressure (normal to low-normal). So, IV NS must be given to correct the underlying cause (volume depletion) and replete Cl-. This will prevent aldosterone secretion and K will correct on its own.

    With K of 2.8, KCl should also be given. Even though it’s not in the options, the best answer is still IV NS.

    Then psych consult to admit for 2-3 days to break cycle of purging.

    Side note: Alkalosis can lead to hypocalcemia 2/2 increased binding of Ca to albumin -> perioral numbness

  20. (B),(a)this is chloride responsive metabolic alkalosis due to excessive vomitng.the main line of treatment is correction of volume contraction by normal saline

  21. BD

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