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Old 05-29-2012
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Urine Sample What is the cause of acidic urine in hyperemesis?

A 28-year-old-patient, gravida 3, para 1, in her 20th week of gestation, is admitted to your service from the emergency room for management of hyperemesis. Her vomiting began 2 days ago. She has no diarrhea or other complaints, has always been healthy, and takes no medications. Vital signs are temperature, 98.8F (37.1C); blood pressure (BP), 120/70 mm Hg sitting and 100/60 mm Hg standing; heart rate (HR), 80 beats/min sitting and 100 beats/min standing; respiration rate (RR), 12 breaths/min. Physical examination is notable for dry mucous membranes and decreased skin turgor. A grade II/VI systolic murmur is present, best heard at the lower left sternal border. Review of the patient's admission labs shows a urine pH of 4.0. In this patient, what is the most likely underlying cause of her urine pH value?

A. Hyperchloremia
B. Hypokalemia
C. Hypovolemia
D. Metabolic acidosis
E. Metabolic alkalosis
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Originally Posted by tyagee View Post
A 28-year-old-patient, gravida 3, para 1, in her 20th week of gestation, is admitted to your service from the emergency room for management of hyperemesis. Her vomiting began 2 days ago. She has no diarrhea or other complaints, has always been healthy, and takes no medications. Vital signs are temperature, 98.8F (37.1C); blood pressure (BP), 120/70 mm Hg sitting and 100/60 mm Hg standing; heart rate (HR), 80 beats/min sitting and 100 beats/min standing; respiration rate (RR), 12 breaths/min. Physical examination is notable for dry mucous membranes and decreased skin turgor. A grade II/VI systolic murmur is present, best heard at the lower left sternal border. Review of the patient's admission labs shows a urine pH of 4.0. In this patient, what is the most likely underlying cause of her urine pH value?

A. Hyperchloremia
B. Hypokalemia
C. Hypovolemia
D. Metabolic acidosis
E. Metabolic alkalosis
The action of aldosterone in hypovolemia --> acidic urine
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Originally Posted by tyagee View Post
A 28-year-old-patient, gravida 3, para 1, in her 20th week of gestation, is admitted to your service from the emergency room for management of hyperemesis. Her vomiting began 2 days ago. She has no diarrhea or other complaints, has always been healthy, and takes no medications. Vital signs are temperature, 98.8F (37.1C); blood pressure (BP), 120/70 mm Hg sitting and 100/60 mm Hg standing; heart rate (HR), 80 beats/min sitting and 100 beats/min standing; respiration rate (RR), 12 breaths/min. Physical examination is notable for dry mucous membranes and decreased skin turgor. A grade II/VI systolic murmur is present, best heard at the lower left sternal border. Review of the patient's admission labs shows a urine pH of 4.0. In this patient, what is the most likely underlying cause of her urine pH value?

A. Hyperchloremia
B. Hypokalemia
C. Hypovolemia
D. Metabolic acidosis
E. Metabolic alkalosis
paradoxical aciduria......??? may be B.......
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Originally Posted by K06100 View Post
paradoxical aciduria......??? may be B.......
can u please explain paradoxical aciduria further...thanks..
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Originally Posted by tyagee View Post
can u please explain paradoxical aciduria further...thanks..
Pure gastric losses result in volume depletion
The excess loss of Cl depletes extracellular chloride and with the luminal loss of Hydrogen ions produces a metabolic alkalosis. The kidney tries to initially maintain blood pH by excreting an alkaline urine. HCO3 is excreted with Na and K until the overall volume deficit triggers an expansion of the extracellular volume rather than maintenance of pH. Na is resorbed, but K is lost via an aldosterone mediated mechanism and this leads to excretion of H ion resulting in "paradoxical aciduria" in an alkalotic patient.

but the what's responsible isn't the Potassium its the hypovolemia right
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Quote:
Originally Posted by tyagee View Post
A 28-year-old-patient, gravida 3, para 1, in her 20th week of gestation, is admitted to your service from the emergency room for management of hyperemesis. Her vomiting began 2 days ago. She has no diarrhea or other complaints, has always been healthy, and takes no medications. Vital signs are temperature, 98.8F (37.1C); blood pressure (BP), 120/70 mm Hg sitting and 100/60 mm Hg standing; heart rate (HR), 80 beats/min sitting and 100 beats/min standing; respiration rate (RR), 12 breaths/min. Physical examination is notable for dry mucous membranes and decreased skin turgor. A grade II/VI systolic murmur is present, best heard at the lower left sternal border. Review of the patient's admission labs shows a urine pH of 4.0. In this patient, what is the most likely underlying cause of her urine pH value?

A. Hyperchloremia
B. Hypokalemia
C. Hypovolemia
D. Metabolic acidosis
E. Metabolic alkalosis
C
Agree on aldosterone action
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Originally Posted by tyagee View Post
can u please explain paradoxical aciduria further...thanks..
Paradoxical aciduria---
the loss of Hcl due to vomiting leads to a transient increase in pH.....the kidney responds by excretion of Na+or K+ bicarbonate....as the vomiting persists,the alkalemic and dehydrated patient tries to conserve sodium thru RAAS....therefore while bicarbonate excretion persists due to alkalosis,it is primarily excreted with K+ rather than Na+ due to dehydration...compensating by conserving Na+ and excreting bicarbonate at the expense of K+ soon fails bcoz in the presence of severe hypokalemia,the kidney begins to exchange H+ in DCT in order to conserve K+....therefore acidic urine in the setting of volume contraction and alkalosis is primarily due to hypokalemia.....
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In volume contraction states as far as i remember hco3 is conserved instead of excretion Which causes contraction alkalosis
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Paradoxical aciduria---
the loss of Hcl due to vomiting leads to a transient increase in pH.....the kidney responds by excretion of Na+or K+ bicarbonate....as the vomiting persists,the alkalemic and dehydrated patient tries to conserve sodium thru RAAS....therefore while bicarbonate excretion persists due to alkalosis,it is primarily excreted with K+ rather than Na+ due to dehydration...compensating by conserving Na+ and excreting bicarbonate at the expense of K+ soon fails bcoz in the presence of severe hypokalemia,the kidney begins to exchange H+ in DCT in order to conserve K+....therefore acidic urine in the setting of volume contraction and alkalosis is primarily due to hypokalemia.....
nice one, but at the end correcting the Potassium wont raise urine PH right and this cycle is stopped only by replacing fluid which dampen RAAS and no more H & K loss in urine, right
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nice one, but at the end correcting the Potassium wont raise urine PH right and this cycle is stopped only by replacing fluid which dampen RAAS and no more H & K loss in urine, right
I think correcting potassium will stop excetion of H+ in urine and conserve H+ (thats what we need in metabolic alkalosis) and replacing fluid will decrease RAAS activity preventing bicarbonate formation too.....thus helping in overcomiing metabolic alkalosis........

but m not sure of what I said.....
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E. Metabolic alkalosis

Quote:
Prolonged and excessive vomiting depletes the body of water (dehydration), and may alter the electrolyte status. Gastric vomiting leads to the loss of acid (protons) and chlorine directly. Combined with the resulting alkaline tide, this leads to hypochloremic metabolic alkalosis (low chloride levels together with high HCO3 and CO2 and increased blood pH) and often hypokalemia (potassium depletion). The hypokalemia is an indirect result of the kidney compensating for the loss of acid.

Last edited by Novobiocin; 05-29-2012 at 01:24 PM.
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This depletion of hydrochloric acid causes a hypochloremic metabolic alkalosis and dehydration because of the loss of H+ and Cl- ions in addition to fluid. Renal compensation for this loss of H+ ions is by preserving protons at the expense of potassium and thus hypokalemia ensues with now, hypochloremic, hypokalemic metabolic alkalosis.

If correction is not undertaken, H+ will begin to be excreted in the urine with the develpment of the "paradoxical aciduria".
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Quote:
Originally Posted by tyagee View Post
A 28-year-old-patient, gravida 3, para 1, in her 20th week of gestation, is admitted to your service from the emergency room for management of hyperemesis. Her vomiting began 2 days ago. She has no diarrhea or other complaints, has always been healthy, and takes no medications. Vital signs are temperature, 98.8F (37.1C); blood pressure (BP), 120/70 mm Hg sitting and 100/60 mm Hg standing; heart rate (HR), 80 beats/min sitting and 100 beats/min standing; respiration rate (RR), 12 breaths/min. Physical examination is notable for dry mucous membranes and decreased skin turgor. A grade II/VI systolic murmur is present, best heard at the lower left sternal border. Review of the patient's admission labs shows a urine pH of 4.0. In this patient, what is the most likely underlying cause of her urine pH value?

A. Hyperchloremia
B. Hypokalemia
C. Hypovolemia
D. Metabolic acidosis
E. Metabolic alkalosis


So... this one is really hard one

i think both hypovolemia and hypokalemia are doing the job producing acidic urine, but after a little research (lol) i assume that hypokalemia is more dominant mechanism in this case.

is this patient there are 2 major ways to loose plasma kalium:
I: alkalotic condition -> intracellular shift of K
II. vomiting -> hence it contains large amount ot KCL as a part of acidic secrete.

So hypokalemia is severe. body (kidney) in this case tries to avoid HYPOKALEMIA more than METABOLIC ALKALOSIS, thus chaning it's action in the distal tubular cells i.e. NA / K exchanger is replaced by NA/H exchanger. it kinda chooses between two bad guys it looses H, but retains K preventing severe hypokalemia and potential arrhythmia, hence the term paradoxical aciduria.

after this mindf***ing thinking i assume answer is more b - hypokalemia than c-Hypovolemia.





p.s. tyagee post answer please asap very good question !
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actually it is one of the UW ques for step 1......for which the answer was HYPOKALEMIA......

but now I don't know whether still the answer is same or not.......
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E. Metabolic alkalosis
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Explanation
Option C (Hypovolemia) is correct. A patient with clinical dehydration and protracted vomiting most likely has an initial hypochloremic metabolic alkalosis, because of GI loss of HCl. Initially, renal Na+ and HCO3− excretion increases to compensate for the increased Cl- reabsorption as the kidneys attempt to correct the hypochloremia. This causes alkalotic urine. With protracted vomiting and subsequent extracellular volume depletion, increased Na+ reabsorption and compensatorily increased urinary K+ and H+ excretion occurs in an attempt to preserve Na+ and maintain extravascular volume. The initially alkalotic urine thus becomes acidotic (paradoxic aciduria).

Option A (Hyperchloremia) is incorrect. Patients with protracted vomiting have increased GI loss of HCl. This should result in hypochloremia. Renal compensatory factors or associated acid-base or electrolyte abnormalities would not result in hyperchloremia. Hyperchloremia would not result in acidotic urine

Option B (Hypokalemia) is incorrect. GI loss of HCl does not initially cause hypokalemia. With protracted vomiting, the ensuing volume depletion results in renal sodium retention partially in exchange for potassium excretion. Hypokalemia, however, is not the mechanism for the acidotic urine. Increased H+ exchange for Na+ is the cause of this paradoxic aciduria.

Option D (Metabolic acidosis) is incorrect. A patient with clinical dehydration and protracted vomiting most likely has an initial hypochloremic metabolic alkalosis because of gastrointestinal (GI) loss of HCl. Initially, renal Na+ and HCO3− excretion increases to compensate for the increased Cl- reabsorption as the kidneys attempt to correct the hypochloremia. This causes alkalotic urine. With protracted vomiting and subsequent extracellular volume depletion, increased Na+ reabsorption and compensatorily increased urinary K+ and H+ excretion occurs in an attempt to preserve Na+ and maintain extravascular volume. The initially alkalotic urine thus becomes acidotic (paradoxic aciduria).

Option E (Metabolic alkalosis) is incorrect. A patient with clinical dehydration and protracted vomiting most likely has an initial hypochloremic metabolic alkalosis because of GI loss of HCl. Initially, renal Na+ and HCO3− excretion increases to compensate for the increased Cl- reabsorption as the kidneys attempt to correct the hypochloremia. This causes alkalotic urine. With protracted vomiting and subsequent extracellular volume depletion, increased Na+ reabsorption and compensatorily increased urinary K+ and H+ excretion occurs in an attempt to preserve Na+ and maintain extravascular volume. The initially alkalotic urine thus becomes acidotic (paradoxic aciduria)
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I think that H and K excretion isn't in order. i.e. First K then H when K is depleted.
Na exchange for both H & K at the same time. But when the body K get depleted it will try to minimize N/K at the expense of increasing N/H leading to more H exteted than before, and thats all attributable to hypovolemia that if stopped everything will go back to nl
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