Interesting clinic case. 30 yo man referred for polyuria. No medical history and no Rx medications. Normal BP, weight 65kg.
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24h urine collection:
Volume: 5L
UNa 20 mmol/L
UK 10 mmol/L
Uureanitrogen 31g
Uosm 283 mOsm/kg
Is this a solute or water diuresis? Urine osmolality of 283 mOsm/kg x 5L urine = 1415 mosm/d = solute diuresis (normal should be 700-1000/d depending on diet)
Volume: 5L
UNa 20 mmol/L
UK 10 mmol/L
Uureanitrogen 31g
Uosm 283 mOsm/kg
Is this a solute or water diuresis? Urine osmolality of 283 mOsm/kg x 5L urine = 1415 mosm/d = solute diuresis (normal should be 700-1000/d depending on diet)
But what's driving the solute diuresis?
Using our urine results:
2*(UNa+Uk)*Uvol = 2(20+10)*5L = 300 mosm
For Uureanitrogen: 31g/5L = 6.2 g/L = 620 mg/dL then divide by 2.8 to get mOsm/L = 221 mOsm/L x 5 L = 1107 mosm/d
I.e main problem here is urea nitrogen
Using our urine results:
2*(UNa+Uk)*Uvol = 2(20+10)*5L = 300 mosm
For Uureanitrogen: 31g/5L = 6.2 g/L = 620 mg/dL then divide by 2.8 to get mOsm/L = 221 mOsm/L x 5 L = 1107 mosm/d
I.e main problem here is urea nitrogen
You can use Uureanitrogen to estimate protein intake with the following equation:
Protein intake = (Uureanitrogen + (wt x 0.031 g nitrogen/kg/d)) x 6.25
In our case: protein intake =(31g +(65kg x0.031)) * 6.25 = 206g protein intake
Protein intake = (Uureanitrogen + (wt x 0.031 g nitrogen/kg/d)) x 6.25
In our case: protein intake =(31g +(65kg x0.031)) * 6.25 = 206g protein intake
That's >3g/kg/d of protein, which he was using for muscle building.
Decreasing protein intake led to improvement in polyuria
He was discharged from clinic
Decreasing protein intake led to improvement in polyuria
He was discharged from clinic
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