Exam 3 - Kidney Flashcards
What are the responsibilities of the kidneys?
A = Acid/base
W = Water
E = Electrolytes
T = Toxin Removal
B = Blood Pressure Regulation
E = Erythropoietin
D = Vitamin D Activation
What does the kidneys excrete?
Hydrogen Ions, Urea, and Creatinine
What is the significance of hydrogen ions in kidney function?
Hydrogen is acidic; if kidneys are functioning, you will see metabolic acidosis.
What is urea?
A waste product of ammonia (detoxed in liver) filtered down to kidneys.
BUN – Blood urea Nitrogen (How much concentration of urea do we have in blood?)
What is creatinine?
A byproduct of muscle breakdown.
What are the normal lab values for BUN?
7 – 20 mg/dl
What are the normal lab values for creatinine in men?
0.7 to 1.3 mg/dL (61.9 to 114.9 μmol/L)
What are the normal lab values for creatinine in women?
0.6 to 1.1 mg/dL (53 to 97.2 μmol/L)
What does specific gravity in urine indicate?
Shows concentration; 1.03 = very concentrated.
What is the relationship between GFR and creatinine?
GFR is roughly 3 times that of creatinine.
What does an increase in both BUN and creatinine indicate?
Kidney problem.
What does an increased BUN with normal creatinine suggest?
Most likely dehydration.
How does kidney disease impact morbidity and mortality?
It is a predictor of major cardiac events and has a direct relationship between GFR and postoperative morbidity & mortality.
What is the risk increase for death and cardiac issues with early stage CKD?
2-5 fold increase.
What are the effects of renal disease on length of stay (LOS)?
Increase in length of stay.
What defines chronic kidney disease (CKD)?
Decrease GFR < 60 for greater than 3 months, representing at least ½ loss of adult kidney function.
How is GFR calculated?
Using the Modified Diet in Renal Disease equation or Cockcroft - Gault equation.
How is GFR reported?
On a basic metabolic profile.
What are the challenges in diagnosing the preoperative setting under kidney standpoints?
It may be difficult due to the 3-month requirement to diagnose. Take a good history including hypertension, diabetes, obesity, heart failure, cirrhosis, and ethnicity (African American, American Indian, Hispanic, Pacific Islander).
What are the blood pressure targets for patients with hypertension and CKD under 60 years?
Blood pressure should be less than 140/90.
What are the blood pressure targets for patients with hypertension and CKD over 60 years?
Blood pressure should be less than 150/90.
What are the first-line therapies for hypertension in CKD?
ACE inhibitors (ACEI) and Angiotensin II receptor blockers (ARB) are first-line therapies due to their renal protective effects.
What should be considered regarding blood pressure control during surgery?
It is important to weigh the risks for blood pressure control with possible hypotension during surgery.
What are common causes of anemia in CKD?
Iron deficiency and erythropoietin deficiency or hyporesponsiveness. Transfusion may be required.
What is the goal hemoglobin level for patients with CKD?
The goal hemoglobin level is 11-12 g/dl, but should not exceed 13 g/dl.
What medications should be avoided in CKD?
Non-steroidals, IV contrast dye, metformin, lithium, digoxin. Avoid ACEI and ARB 24-48 hours preoperatively.
What is the incidence of acute kidney injury (AKI) in hospitalized patients?
AKI occurs in 2-18% of all hospitalized patients and 20-57% of all ICU patients.
What is the leading cause of AKI in hospitalized patients?
Surgery is the leading cause of AKI in hospitalized patients.
What leads to tubular injuries in AKI?
Hypoperfusion and inflammation lead to tubular injuries.
What is ‘renal angina’?
‘Renal angina’ usually refers to a hypoperfusion state.
What lab ratios indicate intra-renal AKI severity?
A 10 to 1 ratio of BUN to creatinine indicates intra-renal AKI.
Preoperative assessment and optimization steps for patients at increased risk of CKD:
Measure blood pressure and compare with home readings if available, perform electrocardiogram, assess functional capacity using the Duke activity status index, check for volume overload (e.g., pedal edema, pulmonary rales), evaluate serum creatinine/eGFR, check serum electrolytes, assess hemoglobin level, review urinary albumin–creatinine ratio from the past year, check Hemoglobin A1c in diabetic patients, encourage smoking cessation, promote routine exercise, and optimize nutritional status with a healthy BMI (20–25)
Definition and staging criteria of AKI-RIFLE
Risk: Creatinine increased 1.5× or GFR decreased ≥25%, UOP <0.5 mL/kg/hr for ≥6 hrs
Injury: Creatinine increased 2× or GFR decreased ≥50%, UOP <0.5 for ≥12 hrs
Failure: Creatinine increased 3× or GFR decreased ≥75%, or Cr ≥4.0 mg/dL with acute rise ≥0.5 mg/dL, UOP <0.5 for ≥24 hrs or anuria for ≥12 hrs
Loss: Persistent ARF, complete loss for >4 weeks
ESRD: Requires dialysis, permanent renal replacement therapy
Definition and staging criteria of AKI-AKIN
Stage 1: Cr increased 1.5× or >0.3 mg/dL, UOP <0.5 for ≥6 hrs
Stage 2: Cr increased 2×, UOP <0.5 for ≥12 hrs
Stage 3: Cr increased 3× or ≥4.0 mg/dL (acute rise ≥0.5 mg/dL), UOP <0.3 for ≥24 hrs or anuria for ≥12 hrs
What is the treatment of choice for End-Stage Renal Disease (ESRD)?
Renal transplant is the treatment of choice for ESRD.
What are the organ wait times for renal transplants?
Organ wait times can exceed 4 years.
What GFR level indicates the need for a renal transplant?
A GFR of less than 20% indicates the need for a renal transplant.
What laboratory tests are required for pretransplant testing?
CBC, platelet count, electrolytes, PTH, amylase, lipase, liver function studies, albumin, prothrombin time, INR, lipid profile, HGA1c, viral serology (HIV, HBV, HCV, EBV, CMV), tissue typing & panel reactive antibody, blood typing.
What cardiac tests are indicated for pretransplant testing?
ECG, stress testing (with imaging), and echocardiography as indicated by cardiovascular risk.
What pulmonary tests are part of pretransplant testing?
Chest X-ray (CXR) and pulmonary function tests (PFTs).
What age-appropriate cancer screenings are required before renal transplant?
PSA, mammography, colonoscopy, and PAP smear.
What psychosocial factors are assessed in pretransplant testing?
Social and financial supports, ability to adhere, substance abuse or psychiatric history, understanding of transplant risks and benefits.
What are some contraindications for renal transplant?
Active acute infection or malignancy, uncontrolled systemic disease, uncontrolled psychiatric disorder or substance abuse, evidence of treatment nonadherence, limited life expectancy due to advanced lung disease or heart failure, and lack of adequate social and financial support.
What is the reevaluation interval for low-risk patients?
Every 3 years
Low-risk patients include those aged 18-45 years, ESRD with no other major comorbidities, and no psychiatric disorders.
What is the reevaluation interval for intermediate-risk patients?
Every 2 years
Intermediate-risk patients include those aged 46-59 years with various risk factors such as previous failed transplantation, dialysis for > 2 years, and more.
What is the reevaluation interval for high-risk patients?
Every year
High-risk patients include those aged ≥ 60 years or with multiple cardiac risk factors, symptomatic cardiovascular disease, and other serious conditions.
What is Contrast Induced Acute Kidney Injury (CI-AKI)?
Dye is used to better visualize structures under x-ray.
What are the recommendations to prevent CI-AKI?
Obtain baseline Cr level & eGFR, limit CM volume, use preheated iso-osmolar CM, avoid high-osmolar CM, avoid repeated doses, avoid dehydration, and administer isotonic saline hydration.
Isotonic saline hydration includes 0.9% NaCl with NaHCO3.
What is the hydration protocol for inpatients to prevent CI-AKI?
0.9% NaCl at 1.5 mL/kg/hr for 12 hours before and after the procedure; NaHCO3 infusion at 3 mL/kg/hr for over 6 hours.
What is the hydration protocol for outpatients to prevent CI-AKI?
0.9% NaCl plus NaHCO3 at 3 mL/kg/hr over a minimum of 1 hour, preferably over 6 hours.
Mitigating risk of CIN based on GFR:
GFR >60 mL/min – Low risk: No prophylaxis or follow-up needed.
GFR 45–59 mL/min – Low to moderate risk if no risk factors: No prophylaxis needed unless receiving intra-arterial contrast, then preventative measures recommended.
GFR 30–45 mL/min – Moderate to high risk: Stop nephrotoxic meds (especially metformin), give IV hydration (isotonic NaCl or NaHCO₃), consider sodium bicarbonate and/or N-acetylcysteine; follow-up in SCr 48–72 hrs.
GFR <30 mL/min – High risk: Avoid contrast if possible, use non-ionic agents, consult nephrology, consider hemodialysis, same prevention as GFR 30–45; follow-up in SCr 24–72 hrs.
