Acute Kidney Injury Flashcards
What 3 principles are desirable in theory for a good assessment of renal function?
- Measurable
- Reproducible
- Consistent
Which of the following is not a desirable, theoretical good assessment of renal function?
A. Reproducible
B. Consistent
C. Measurable
D. Traceable
D. Traceable
What is used as a measurement of renal function?
GFR/eGFR
What is the equation for GFR?
[X]urine x urine flow rate / [X] plasma
What is the ideal criteria for a marker of GFR?
Principles of GFR marker: GFRR
• Gain: Appear in plasma at constant rate
• Filtered: Freely filtered at glomerulus
• Reabsorbed: Not reabsorbed or secreted by renal tubule
• Renal: Does not undergo extra-renal elimination
Which of the following is not a criteria for a marker used to estimate GFR?
A. Appear in the plasma at a constant rate
B. Freely filtered at the glomerulus
C. Reabsorbed/secreted by renal tubule
D. Does not undergo extra-renal elimination
C. Reabsorbed/secreted by renal tubule
What is the most commonly used marker for estimation of GFR?
A. Inulin
B. Cystatin
C. Creatinine
D. Urea
C. Creatinine
What is inulin and why is it good as an exogenous marker of GFR?
Why may it not be useful?
Plant polysaccharide of fructose.
Constant injection of inulin for 3 hour at 18mg/min with timed urine and blood collection to measure inulin at midpoints of collection period
+ Gold standard
+ Fulfils marker criteria (constant, not produced elsewhere, not secreted/absorbed, only renally excreted)
+ Comprehensive assessment via blood and urine output/sampling
- Time-consuming
- Resources
- Difficult to perform
What is cystatin and why is it good as an marker of GFR?
Why may it not be useful?
Cysteine protease inhibitor present on surface of nucleated cells shed into plasma and excreted by glomerular filtration
+ More stable than creatinine
+ Less interpersonal and intrapersonal variation
+ Better for elderly populations
+ Freely filtered, reabsorbed and metabolised by PT cells, not produced elsewhere, only renally excreted)
+ 13kDa
- Expensive
- Difficult (laboratory specific)
- Not validated
What is Creatinine and why is it good as an marker of GFR?
Why may it not be useful?
Metabolic product of creatine and phosphocreatine released at a constant rate by the body
Note: Plasma creatinine inversely related to GFR by 2 thus halving GFR ≈ x2 plasma creatinine concentration
+ Does not bind plasma proteins
+ Freely filtered
+ Little reabsorption
+ Low M/w 113Da
- Secreted by tubules (breakdown from muscle) - Increased error at lower GFR
- Relations to muscle mass - Inaccuracy in GFR determination by creatinine clearance due to collection and measurement
- Insensitive in acute kidney injury (AKI)
- Deranged in diet (meat), muscle mass (elevated), age (decrease), vegetarians (decrease),
- Drugs interfere: Trimethoprim, cimetidine compete for secretion and other substances (bilirubin, cephalosporin, high glucose)
What is Urea and why is it good as an marker of GFR?
Why may it not be useful?
Metabolic product of amino acids and exogenously acquired from protein intake
+ Freely filtered
+ Low M/w of 60Da
- 50% reabsorbed by PCT depending on water/Na reabsorption
- Deranged by liver disease (reduced urea plasma levels)
- Proteinolysis in the intestines raises urea
Which of the following markers is useful in elderly populations and has less interpersonal variation?
A. Inulin
B. Cystatin
C. Creatinine
D. Urea
B. Cystatin
Which of the following markers is endogenous and does not bind plasma proteins?
A. Inulin
B. Cystatin
C. Creatinine
D. Urea
C. Creatinine
Which of the following markers is endogenous and can be interfered with in AKI or Drugs?
A. Inulin
B. Cystatin
C. Creatinine
D. Urea
C. Creatinine
Which of the following markers is endogenous and is freely filtered but up to 50% is reabsorbed by PCT?
A. Inulin
B. Cystatin
C. Creatinine
D. Urea
D. Urea
What are the indications when clearance measurements based on serum creatinine may be inaccurate?
- Old age
- BMI
- MSK diseases
- Paraplegia/Quadriplegia
- Diet (carnivorous or vegetarian)
- Rapidly changing kidney function
- Pregnancy
What is the relationship between age and GFR?
Increasing age from 20 onwards leads to a gradual, physiological reduction in GFR
How can eGFRs be calculated? List the main formulas used.
1. MDRD: Formula to estimate GFR • Computerised • Useful is stable creatinine • Clinically used • Modifier for F (0.742) and Black (1.21)
• Less accurate if near normal GFR
- CKD-EPI: Formula estimating GFR
• Best estimation of GFR
• Clinically used (for donors)
• Modifier for Age (0.993), F (1.018), Black (1.159)
• Not validated yet (used for donors)
- Cockcroft-Gault Equation: Based on serum creatinine alone
• Advised for narrow therapeutic index drugs
- Inaccurate for rapidly changing creatinine levels
- Uses IBW at extremes of BW
- Adults only
- Not adjusted for SA
Which of the following equations is used for donors and gives the best estimation of GFR?
A. CKD-EPI
B. Cockcroft-Gault Equation
C. MDRD
A. CKD-EPI
Which of the following equations is used for clinically and useful is stable creatinine?
A. CKD-EPI
B. Cockcroft-Gault Equation
C. MDRD
C. MDRD
Which of the following equations is used when narrow therapeutic index drugs are used?
A. CKD-EPI
B. Cockcroft-Gault Equation
C. MDRD
B. Cockcroft-Gault Equation
Which of the following equations is only applicable to adults?
A. CKD-EPI
B. Cockcroft-Gault Equation
C. MDRD
B. Cockcroft-Gault Equation
What relationship does renal blood flow have on kidney function? What endogenous marker is used? Equation used to calculate RPF?
Renal blood flow (Renal plasma flow ≈ RPF) ≈ hydraulic pressure in glomerulus based on afferent and efferent arteriolar radius ≈ ∆ GFR
- Kidneys take 20% CO ≈ 20% of 5L/min ≈ 1/L min
Which of the following is a marker for Renal Plasma Flow (RPF)?
A. Butyric acid
B. Urea
C. Para-aminohippurate
D. Creatining
C. Para-aminohippurate
What impact would an increase in the diameter of the afferent arteriole have on filtration?
A. Increase as less perfusion
B. Increase as more perfusion
C. Decrease as less perfusion
D. Decrease as more perfusion
B. Increase as more perfusion
What impact would a decrease in the diameter of the afferent arteriole have on filtration?
A. Increase as less perfusion
B. Increase as more perfusion
C. Decrease as less perfusion
D. Decrease as more perfusion
C. Decrease as less perfusion
What impact would an increase in the diameter of the efferent arteriole have on filtration?
A. Increase as less perfusion
B. Increase as more pressure across the glomerulus
C. Decrease as less perfusion
D. Decrease as reduced pressure across the glomerulus
D. Decrease as reduced pressure across the glomerulus
What impact would a decrease in the diameter of the efferent arteriole have on filtration?
A. Increase as less perfusion
B. Increase as more pressure across the glomerulus
C. Decrease as less perfusion
D. Decrease as reduced pressure across the glomerulus
B. Increase as more pressure across the glomerulus
What effect does NSAID have on GFR?
A. Agonist of COX-1 and COX-2 at peroxidase site thus increase conversion of arachidonic acid to PDH2 synthetases and subsequent prostaglandin increasing GFR
B. Antagonist of COX-1 and COX-2 at peroxidase site thus reduce conversion of arachidonic acid to PDH2 synthetases and subsequent prostaglandin decreasing GFR
C. Antagonist of COX-1 and COX-2 at cycloxygenase site thus reduce conversion of arachidonic acid to PDH2 synthetases and subsequent prostaglandin decreasing GFR
D. Antagonist of COX-1 and COX-2 at cycloxygenase site thus reduce conversion of arachidonic acid to PDH2 synthetases and subsequent prostaglandin decreasing GFR
D. Antagonist of COX-1 and COX-2 at cycloxygenase site thus reduce conversion of arachidonic acid to PDH2 synthetases and subsequent prostaglandin decreasing GFR
What impact does ACEi have on GFR?
A. Inhibit AGT-II production thus constrict afferent arterioles to reduce GFR
B. Increase AGT-II production thus dilate afferent arteriole to increase GFR
C. Inhibit AGT-II production ≈ dilate efferent arterioles ≈ reduce pressure gradient across glomerulus to reduce GFR
D. Inhibit AGT-II production ≈ constrict efferent arterioles ≈ reduce pressure gradient across glomerulus to increase GFR
C. Inhibit AGT-II production ≈ dilate efferent arterioles ≈ reduce pressure gradient across glomerulus
What impact do ARBs have on GFR?
A. Inhibit AGT-II production thus constrict afferent arterioles to reduce GFR
B. Increase AGT-II production thus dilate afferent arteriole to increase GFR
C. Inhibit AGT-IIR binding ≈ dilate efferent arterioles ≈ reduce pressure gradient across glomerulus to reduce GFR
D. Inhibit AGT-IIR binding ≈ constrict efferent arterioles ≈ reduce pressure gradient across glomerulus to increase GFR
C. Inhibit AGT-IIR binding ≈ dilate efferent arterioles ≈ reduce pressure gradient across glomerulus to reduce GFR
Which radionuclide is best for envisaging renal scarring and mass?
A. MAG3
B. DMSA
C. 51Cr-EDTA
D. Creatinine
B. DMSA
Which radionuclide is an independent indicator of ERPF and renal function?
A. MAG3
B. DMSA
C. 51Cr-EDTA
D. Creatinine
A. MAG3
Which radionuclide emits a lower radiation dose thus may be safer relatively?
A. MAG3
B. DMSA
C. 51Cr-EDTA
D. Creatinine
C. 51Cr-EDTA
Which radionuclide has a high extraction fraction of 40-50%?
A. MAG3
B. DMSA
C. 51Cr-EDTA
D. Creatinine
A. MAG3
Define Proteinuria.
≥ 0.3g in 24 hours (albumin)
List 3 states/conditions which may give variations in urinary albumin.
- Posture
- Exercise
- Acute diuresis
- Menstruation
- Does not detect light chains in urine (e.g. Bence Jones protein)
What are the two sites of EPO production?
1) Kidney: 90%
2) Liver: 10%
What impact does acidosis have on Haemoglobin production?
Outline the physiological mechanism for this.
Acidosis reduces Erythropoiesis.
MOA: Acidosis ≈ reduced O2 affinity of Hb thus increasing tissue oxygenation ≈ reduce EPO synthesis by type 1 fibroblastoid cells in peritubular interstitium of cortex and outer medulla ≈ reduce erythropoiesis
What influence does CKD have on Haemoglobin production?
CKD ≈ myofibroblastoid change of fibroblastoid cells ≈ less erythropoietin production
What are the sites of calcium absorption in the body?
- Bone turnover (resorption)
- Gut (absorption)
- Kidney (filtered and reabsorbed)
What is renal calcium filtration and reabsorption regulated by?
- Vitamin D
- PTH (increased by low calcium ≈ bone reabsorption and vitamin D synthesis)
What influence will hypocalcemia have on PTH and what should occur?
Hypocalcemia ≈ CaSR in PTH detects + triggered ≈ Increase vitamin D synthesis (absorption of calcium) + calcium resorption/liberation ≈ correct Ca:PO4
Case Study… Mr Oliver - 53 Y/o M - Moderate pain - Gross ascites - 3 weeks Hx of ankle swelling - SOBE worsened 1/52 - Unsteady - Smells of alcohol
- PMHx: alcoholic liver disease and cirrhosis
- DHx: Spironolactone 100mg daily, lactulose 20ml BD (reduce hepatic encephalopathy), Maalox
Raised Bilirubin, Alk Phos, GGT; low albumin, increased PT
i) What are the main therapeutic aims for Mr Oliver?
ii) What prescribing considerations are there for Mr. Oliver?
i)
- Relieve ascites/oedema
- Treat any infection
- Prevent complications of alcohol withdrawal
- Prevent VTE
- Provide nutritional support
- Refer patient for alcohol probe
ii)
- Cirrhosis of liver
- Low serum albumin
- Cerebral sensitivity increased
- High risk of VTE despite prolonged PT but also risk of bleeding. Gastric irritation
- increase bleeding tendency
- Caution with nephrotoxics
List 5 common prescribing considerations regarding renal function and status.
- Renal condition/Degree of renal impairment
- Risks associated with prescribing
- Nephrotoxic drugs
- Prescribing in AKI, CKD and dialysis
- Acute/Chronic Kidney Disease
- Proportion of drug renally excreted
- Therapeutic window: narrow or wide
- Renal function markers (eGFR or creatinine clearance)
- Nephrotoxic drugs
- Patient on established renal replacement therapy (dialysis, haemodialysis, peritoneal dialysis)
State 3 risks of prescribing on the kidney.
- Reduced renal excretion of drug and metabolites ≈ toxicity
- Sensitivity increased
- Increased risk of ADRs
- Drugs not effective when renal function reduced
- Drug-induced renal disorders more common in pt with CKD
What type of drug-induced AKI would results from excessive diuretics use?
A. Renal
B. Post-Renal
C. Pre-Renal
D. Peri-Renal
C. Pre-Renal
What type of drug-induced AKI would results from excessive Gentamicin use?
A. Renal
B. Post-Renal
C. Pre-Renal
D. Peri-Renal
A. Renal
What type of drug-induced AKI would results from excessive Ciclosporin use?
A. Renal
B. Post-Renal
C. Pre-Renal
D. Peri-Renal
A. Renal
What type of drug-induced AKI would results from excessive Anticholinergics use?
A. Renal
B. Post-Renal
C. Pre-Renal
D. Peri-Renal
B. Post-Renal
What type of drug-induced AKI would results from excessive cytotoxic chemotherapy use?
A. Renal
B. Post-Renal
C. Pre-Renal
D. Peri-Renal
A. Renal
List 5 potentially nephrotoxic drugs and how they may cause damage.
- ACEi
- ARBs
- NSAIDs: COX-i ≈ reduced PGE2 ≈ afferent arteriole vasoconstriction ≈ renal hypoperfusion ≈ reduced GFR and urine volume
- Diuretics: Water/electrolyte loss, increased catabolism, vascular occlusion ≈ ∆ renal haemodynamics
- Lithium
- Digoxin
- Aminoglycosides (e.g. Gentamicin): Nephrotoxic damage
- Vancomycin
- Metformin: Increased risk of metabolic acidosis; avoid if eGFR < 30mL/min
- Nitrofurantoin: Increased risk of ADRs, peripheral neuropathy, blood dyscrasias; contraindicated if eGFR < 30mL/min unless multi-resistant bugs
- Iodinated contrast media
- Opioids (e.g. Morphine): Active metabolites accumulate ≈ increased ASEs
What are medicine sick day rules?
List 3 drugs affected by the medicine sick day rules.
Discontinue drugs during acute intercurrent illness
Condition: • Vomiting • Diarrhea • Fevers • Sweats • Shaking
Drugs:
• ACEi: Reduced constriction of efferent arteriole ≈ GFR reduced
• NSAIDs: Reduced vasodilation of afferent arteriole ≈ GFR reduced
• ARBs: Reduced constriction of efferent arteriole ≈ GFR reduced
• Diuretics: Fluid loss ≈ hypovolemia ≈ reduced GFR
• Others (blood-pressure lowering): Lower blood pressure and GFR
• Metformin: Accumulation
• Sulfonylurea: Risk of hypoglycaemia
• Trimethoprim: Hyperkalemia risk
List 5 principles of prescribing in renal impairment.
- Check renal function: eGFR, creatinine, U+E
- Baseline trends in renal function
- Consider stopping/withholding nephrotoxic drugs
- Choose non-nephrotoxic drug if possible
- Check resources
- Use therapeutic drug monitoring guide dose/frequency if appropriate
- Continue to monitor patient condition: NEWS + Metabolic profile
Which of the following is not a principle of prescribing in renal impairment?
A. Continue to monitor patient condition: NEWS + Metabolic profile
B. Consider stopping/withholding nephrotoxic drugs
C. Baseline trends in renal function
D. Avoid prescribing any nephrotoxic drugs, even at low dose
D. Avoid prescribing any nephrotoxic drugs, even at low dose
Which of the following is not a principle of prescribing in renal impairment?
A. Check renal function: eGFR, creatinine, U+E
B. Consider stopping/withholding nephrotoxic drugs
C. Never choose a nephrotoxic drug
D. Choose non-nephrotoxic drug if possible
C. Never choose a nephrotoxic drug
Outline the relationship between renal clearance and therapeutic window.
Renal clearance (excretion of active drug/metabolite) and therapeutic window (dose range that is therapeutically safe, not toxic) present trade-off of which action taken is dependent on the combination
List 3 drugs to avoid if low clearance and a narrow therapeutic window.
- Theophyline
- Carbamazepine
- Phenytoin
- Rivaroxaban
- Gabapentin
- Ramipril/ACEi
List 3 prescribing principles for a CKD patient.
- Detect CKD early
- Classify CKD (1 to 5)
- Risk Factor for CVD
- Protect renal function: ACEi + ARBs
- Manage complications: hyperkalemia, anaemia, mineral/bone disorders, hyperphosphataemia
- Manage comorbid conditions
- Watch out for AKI
- Renal replacement therapy: Type of dialysis, Dialyser membrane, blood and dialysate flow rate, drugs removed in dialysis (Consult renal department)
Which of the following is not a prescribing principle in a CKD patient?
A. Detect CKD early
B. Classify CKD (1 to 5)
C. Protect renal function: ACEi + ARBs
D. Check if CVD
• Risk Factor for CVD
No, check if you have risk factors
Which of the following is not a prescribing principle in a CKD patient?
A. Risk Factor for CVD
B. Watch out for AKI
C. Classify CKD from stages 1-3
D. Protect renal function: ACEi + ARBs
C. Classify CKD from stages 1-3
No, classify CKD stages from Stages 1-5
List 3 prescribing principles for a patient regarding their liver.
- Liver function: LFTs
- Drug metabolism
- Hypoproteinaemia
- Clotting factors
- Hepatic encephalopathy signs?
- Fluid balance?
- Hepatotoxic drugs?
List 3 types/categories of drugs that worsen liver disease.
- Constipating drugs
- Medicines causing gastrointestinal ulceration
- Sedating medicines
- Anticoagulants, anti-platelets and medicines causing bleeding
- Medicines affecting fluid-electrolyte balance
- Medicines with high sodium content
- Medicines that are nephrotoxic
What is Drug-Induced Liver disease?
Hepatic dysfunction shown by abnormalities in liver tests due to medications
Outline the two categories of Drug Induced Liver disease.
- Intrinsic drug reactions: Predictable, dose-dependent, rapidly (paracetamol OD)
- Idiosyncratic drug reactions: Unpredictable, dose-independent, longer to develop
Which of the following drugs is not likely to cause acute liver failure?
A. Cyclophosphamide
B. Allopurinol
C. NSAIDs
D. Methotrexate
D. Methotrexate
Causes Fibrosis/Cirrhosis