05-28-2014, 09:24 AM
Sara' s labs before Rx
Serum osmolarity - 301 ( all in mosmol/l)
Urine osmolarity - 70
After the diagnosis of central diabetes insipidus had been established, Sara was given a desmopressin shot. In anticipation to get urine osmolarity at least 1000, her attendant repeated the osmolarity assays. Repeated tests showed: urine osmolarity 500, serum osmolarity 298. Provided that dose of ADP given to Sara as well as time for therapeutic effect to develop were adequate, why did Sara's urine get only moderately hyperosmolar even though her serum osmolality meet expectations of the physician to get it near 1000.
a/high sodium content in ultrafiltrate inhibits water reabsorption in early proximal tubule.
b/concentration function of her kidneys has been lost irreversibly due to long-standing disease.
c/She has got GFR above normal
d/It takes time for expression of Na+/K+/2Cl transporter to be induced.
e/Aldosterone may be deficient as well.
Serum osmolarity - 301 ( all in mosmol/l)
Urine osmolarity - 70
After the diagnosis of central diabetes insipidus had been established, Sara was given a desmopressin shot. In anticipation to get urine osmolarity at least 1000, her attendant repeated the osmolarity assays. Repeated tests showed: urine osmolarity 500, serum osmolarity 298. Provided that dose of ADP given to Sara as well as time for therapeutic effect to develop were adequate, why did Sara's urine get only moderately hyperosmolar even though her serum osmolality meet expectations of the physician to get it near 1000.
a/high sodium content in ultrafiltrate inhibits water reabsorption in early proximal tubule.
b/concentration function of her kidneys has been lost irreversibly due to long-standing disease.
c/She has got GFR above normal
d/It takes time for expression of Na+/K+/2Cl transporter to be induced.
e/Aldosterone may be deficient as well.