A diabetic male pt on you rsurgical service recently underwent Bilroth 2 for pPUD. Pt recently began eating, but is not being adequately covered by his insulin doses. the pt.'s rcent blood glucose have been consistently high. this morning u note the Na+ 134mmol/L in addition to glucose being 500mg/dl
Q1. Wat is the corrected Na level?
a. 136
b. 138
c. 140
d. 142
e. 144
Q2. The remainder of the pt's chem panel shows Na+ 134, K+ 4.4, Cl 102, CO2 23, BUN 28 and creat 1.3 mg/dl. the calculated plasma osmolality is:
a.278 mmol/L
b. 306 mmol/L
c. 334 mmol/L
d. 368 mmol/l
e. 404 mmol/l
Q3. An osmolar gap is present if the measured osmolality and calculated osmolality differ by how much?
a. 8 mosm/Kg
b. 10mosm/Kg
c. 12mosm/Kg
d. 15 mosm/Kg
e. 18mosm/Kg
1) as glucose level is so high, this is hyperosmolar/ hypertonic hyponetremia (in case of hyperglycemia plasma Na concentration falls by 1.4mmol/L for every 100mg/dL rise in plasma glucose concentration - from Harrison's)
or
"In marked hyperglycemia, ECF osmolality rises and exceeds that of ICF, since glucose penetrates cell membranes slowly in the absence of insulin, resulting in movement of water out of cells into the ECF. Serum Na concentration falls in proportion to the dilution of the ECF, declining 1.6 mEq/ L for every 100 mg/dL (5.55 mmol/L) increment in the plasma glucose level above normal. This condition has been called translational hyponatremia because no net change in total body water (TBW) has occurred. No specific therapy is indicated, because Na concentration will return to normal once the plasma glucose concentration is lowered."
Source:
2)http://www.emedicine.com/med/topic1091.htm
# Normal serum osmolality ranges from 280-290 mOsm/kg. A serum osmolality of 320 mOsm/kg or more defines HNS. Rarely, serum osmolality may be greater than 400 mOsm/kg. In HNS, higher serum osmolality relates to worse impairment of the level of consciousness.
# The serum osmolality may be calculated by adding Na+ and K+, multiplying by 2, adding glucose (mg/dL) divided by 18, and adding BUN divided by 2.8 (ie, 2 [Na+ + K+] + [mg/dL of glucose/18] + [BUN/2.8]).
3)
SO answers are:
Q1. Wat is the corrected Na level?
c. 140
Q2. calculated plasma osmolality is:
b. 306 mmol/L
Q3. An osmolar gap is present if the measured osmolality and calculated osmolality differ by how much?
b. 10mosm/Kg - Not sure thought
diabetic male pt on you rsurgical service recently underwent Bilroth 2 for pPUD. Pt recently began eating, but is not being adequately covered by his insulin doses. the pt.'s rcent blood glucose have been consistently high. this morning u note the Na+ 134mmol/L in addition to glucose being 500mg/dl
Q1. Wat is the corrected Na level?
a. 136
b. 138
c. 140 ---------
d. 142
e. 144
Corrected Sodium
= Measured sodium + (((Serum glucose - 100)/100) x 1.6)
Alternatively (equivalent equation):
= Measured sodium + 0.016 x (Serum glucose - 100)
Q2. The remainder of the pt's chem panel shows Na+ 134, K+ 4.4, Cl 102, CO2 23, BUN 28 and creat 1.3 mg/dl. the calculated plasma osmolality is:
a.278 mmol/L
b. 306 mmol/L
c. 334 mmol/L
d. 368 mmol/l
e. 404 mmol/l
Measured=2 (Na + K) + (mg/dL of glucose/18) + (BUN/2.8)
2x138.4 + 27.77 + 10==== 314.57
Calculated=2Na+ Sug/18 +BUN/2.8 ====305.77
Q3. An osmolar gap is present if the measured osmolality and calculated osmolality differ by how much?
a. 8 mosm/Kg
b. 10mosm/Kg
c. 12mosm/Kg
d. 15 mosm/Kg
e. 18mosm/Kg
Measured – Calculated = 8
1) as glucose level is so high, this is hyperosmolar/ hypertonic hyponetremia (in case of hyperglycemia plasma Na concentration falls by 1.4mmol/L for every 100mg/dL rise in plasma glucose concentration - from Harrison's)
or
"In marked hyperglycemia, ECF osmolality rises and exceeds that of ICF, since glucose penetrates cell membranes slowly in the absence of insulin, resulting in movement of water out of cells into the ECF. Serum Na concentration falls in proportion to the dilution of the ECF, declining 1.6 mEq/ L for every 100 mg/dL (5.55 mmol/L) increment in the plasma glucose level above normal. This condition has been called translational hyponatremia because no net change in total body water (TBW) has occurred. No specific therapy is indicated, because Na concentration will return to normal once the plasma glucose concentration is lowered."
Source:
2)http://www.emedicine.com/med/topic1091.htm
# Normal serum osmolality ranges from 280-290 mOsm/kg. A serum osmolality of 320 mOsm/kg or more defines HNS. Rarely, serum osmolality may be greater than 400 mOsm/kg. In HNS, higher serum osmolality relates to worse impairment of the level of consciousness.
# The serum osmolality may be calculated by adding Na+ and K+, multiplying by 2, adding glucose (mg/dL) divided by 18, and adding BUN divided by 2.8 (ie, 2 [Na+ + K+] + [mg/dL of glucose/18] + [BUN/2.8]).
3)
Osmolal gap is the difference between measured serum osmolality and calculated serum osmolality.
It is typically calculated as: OG = measured serum osmolality - (2 X serum sodium + serum glucose + serum urea)
Where:
* 2 X serum sodium + serum glucose + serum urea = the calculated serum osmolality and all measures are in mmol/L. = 268+500---------- no urea
* OG = osmolal gap
In US customary units the calculated osmolarity is: ( 2 x sodium ) + glucose/18 + BUN/2.8. = 268+27.77+10= 306
SO answers are:
Q1. Wat is the corrected Na level?
c. 140
Q2. calculated plasma osmolality is:
b. 306 mmol/L
Q3. An osmolar gap is present if the measured osmolality and calculated osmolality differ by how much?
b. 8mosm/Kg -
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