Chronic Kidney Disease Flashcards
What is CKD?
Chronic kidney disease is best thought of as a loss of functioning nephrons.
Decreased functioning nephrons leads to decreased GFR and thus, elevated creatinine and BUN for 3+ months
What are stages of CKD?
1-5 based on eGFR
What are the high risk factors for developing CKD?
- diabetes
- HTN
- cancer
- GI tumors
- etc.
What are the limitations of using serum creatinine as a marker of GFR?
Serum creatinine will slightly over-estimate true GFR because it is secreted AND
as you lose nephrons, the other nephrons can compensate so the GFR will remain high even though there is significant nephron loss occurring
What are some requirements of using formulas to estimate GFR in CKD?
the Pcr must be constant over a significant time period to estimate
NOTE: these formulas account for age, gender, and ethnicity- all factors that influence the GFR
What is the Cockroft-Gault formula for estimating GFR?
(140-age)/Scr*(0.85)- if female
can only be used in a steady state condition (CKD). acute renal failure would not be considered steady state
How is stage 1 CKD defined?
GFR over 90
How is stage 2 CKD defined?
GFR 60-89
How is stage 3 CKD defined?
GFR 30-59
How is stage 4 CKD defined?
GFR 15-29
How is stage 5 CKD defined?
GFR less than 15 or dialysis
T or F. Serum creatinine is always a sufficient method to determine what stage of CKD a patient is in
F. Always have to take into account the demographics of the patient. For instance, a 20 yo AA male with Pcr of 1.3 may be stage 1 but a 20 yo WF with Pcr may be stage 2, etc.
Remember CKD would be a patient with elevated creatinine for 3+ months
Remember CKD would be a patient with elevated creatinine for 3+ months
What are some things you may want to ask a patient with CKD?
Are you having problems voiding urine? If yes, could point to obstructive uropathy
Is your urine abnormal?
Past medical history
What things would you be looking for upon physical exam of a patient with CKD?
- HTN
- flank masses (could suggest PKD)
- edema
A small kidney on ultrasound would indicate what?
chronic disease (9-12 cm normal)
What are some ways kidney disease must be differentiated?
- prerenal, intrinsic, postrenal
- acute or chronic
- glomerular or tubular
- inflammatory or non-inflamm
- with or w/out systemic disease
What things favor CKD over ARF?
patients will have high creatinine and will be less likely to be symptomatic (less N/V)
- presence of peripheral neuropathy (non-specific- diabetes)
- bone changes consistent with longstanding 2ndary hyperPTH
- small echogenic kidneys on ultrasound
- waxy casts on urinalysis
What factors favor tubular vs. glomerular etiology of CKD?
- absence of heavy proteinuria
- inability to concentrate or dilute the urine
- hyperkalemia and metabolic acidosis
So what urine SG would suggest tubular etiology of CKD?
~1.010 (Uosm= 300mOsm/kg)