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Medicine

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Kidney

Question
12 out of 17
 

In which of the following condition serum creatinine is increase out of proportion to BUN?



A Tetracycline
B Muscular body

C High protein diet
D Sickle cell anemia

Ans. B Muscular body

Serum Creatinine (Normal range 0.5-1.2 mg/ml, (Ref, H- 18th Appendix Table 2, Page –3596)

A. Creatinine is produced by the nonenzymatic dehydration of muscle creatine.

B. Because the daily production of creatinine is relatively constant, its clearance is a relatively reliable index of GFR.

C. In people having highly muscular body have more creatinine and people with thin muscle body have low creatinine.

Important Points:

Creatinine clearance rate (CCr or CrCl) is the volume of plasma that is cleared of creatinine per unit time and is a useful measure for approximating the GFR. (Ref: Harrison 18th Edi, Pge- 334)

A. Creatinine clearance, is measured from plasma and urinary creatinine excretion rates for a defined time period (usually 24 h) and is expressed in milliliters per minute: CrCl = (Uvol x UCr)/(PCr x Tmin).

B. Creatinine is useful for estimating GFR because it is a small, freely filtered solute that is not reabsorbed by the tubules.

C. Serum creatinine levels can increase acutely from dietary ingestion of cooked meat, however, and creatinine can be secreted into the proximal tubule through an organic cation pathway (especially in advanced progressive chronic kidney disease), leading to overestimation of GFR.

D. When a timed collection for creatinine clearance is not available, decisions about drug dosing must be based on serum creatinine alone.

E. Two formulas are used widely to estimate kidney function from serum creatinine: (1) Cockcroft-Gault and (2) four-variable MDRD (Modification of Diet in Renal Disease).

Cockcroft-Gault: CrCl (mL/min) = (140 – age (years) x weight (kg) x [0.85 if female])/(72 x sCr (mg/dL)

MDRD: eGFR(mL/min per 1.73 m2) = 186.3 x PCr (e–1.154) x age (e–0.203) x (0.742 if female) x (1.21 if black).

Kidney Flashcard List

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