The Clinical Kidney Part 1

Question 1

general kidney function

Answer 1

filtration through the glomerulus into the nephron unit, reabsorption into the circulation, and then secretion back into the nephron

Question 2

kidneys are involved in endocrine functions

Answer 2

secretes renin, bradykinin, and prostaglandins, Erythropoietin, Calcitriol

Question 3

glomerular filtration rate

Answer 3

Sum of filtration rate in all nephrons (~125 mL/min/1.73m2)
Not precisely correlated to nephron loss
May be measured using ideal filtration markers such as inulin
Typically estimated using creatinine

Question 4

creatinine

Answer 4

Endogenous marker that undergoes filtration and secretion
Production related to muscle mass and diet
Currently most often measured via IDMS assay
must be at steady state to appropriately reflect kidney function

Question 5

24 hour urine collection

Answer 5

UCr x V/ SCr divided by 1.44
UCr (urinary conc of creatinine) in mg/dL
V (urinary flow rate) in L/24 hours
SCr (serum creatinine) in mg/dL
results are in mL/min

Question 6

Estimation of Creatinine Clearance:Cockcroft-Gault Equation

Answer 6

((140 - age) x weight)/(72 x SCr) x (0.85 if female)
age in years, weight in kg, SCr in mg/dL
results in mL/min

Question 7

TBW

Answer 7

total body weight = actual

Question 8

IBW

Answer 8

ideal body weight

2. 3 x (height – 60) + 50 in males
2. 3 x (height – 60) + 45.5 in females

Question 9

ABW0.4

Answer 9

adjusted body weight

0.4 x (TBW – IBW) + IBW

Question 10

if TBW < or equal to 1.3 x IBW

if TBW > 1.3 x IBW

Answer 10

use TBW

use ABW0.4

Question 11

rounding in Cockcroft-Gault Equation

Answer 11

Routine upward rounding of SCr in elderly patients is no longer recommended

Assessment of creatinine production may be used

Question 12

Estimation of Glomerular Filtration Rate: MDRD

modification of diet in renal disease- normalized body surface area

Answer 12

175 ×〖𝑆𝐶𝑟〗^(−1.154) ×〖𝑎𝑔𝑒〗^(−0.203)
[×0.742 𝑖𝑓 𝑓𝑒𝑚𝑎𝑙𝑒][×1.212 𝑖𝑓 𝑏𝑙𝑎𝑐𝑘]

SCr in mg/dL; age in years
**Results in mL/min/1.73m2

Question 13

Estimation of Glomerular Filtration Rate: CKD-EPI

Answer 13

A ×〖(𝑆𝐶𝑟/𝐵)〗^𝐶 ×〖0.993〗^𝑎𝑔𝑒 [×1.159 𝑖𝑓 𝑏𝑙𝑎𝑐𝑘]

Question 14

Cockcroft-Gault, MDRD, and CKD-EPI

CKD- EPI preferred

Answer 14

Greater accuracy at higher GFR

Stronger correlation to adverse outcomes

Higher specificity for kidney disease

Question 15

Cystatin-C

Answer 15

May increase more quickly in acute disease

Initially believed to better predict clinical outcomes

May be combined with creatinine to estimate kidney function

Question 16

urine output

Answer 16

Assess as mL/kg/hr (normal approximately 1 mL/kg/hr)

Oliguria < 500 mL/day

Anuria < 50 mL/day

Question 17

Albuminuria and Proteinuria
ACR and AER

PCR and PER

dipstick

Answer 17

normal/moderately increased/severely increased
<30/30 to 300/ >300

<150 / 150 to 500 / >500

negative to trace/ 1+/ >1+

Question 18

prerenal

Answer 18

decreased perfusion pressure

Question 19

intristic:

Answer 19

direct pathology

• Vascular
• Glomerular
• Tubular-interstitial-tubulointerstitial

Question 20

psotrenal

Answer 20

obstruction of urine flow