Exam 2 (AKI, CKD) Flashcards
Criteria for CKD
If either of the following is present for >3 months
-Markers of kidney damage (one or more)
Albuminuria, urine sediment, electrolyte or other
disorders, H/O transplant, other
-Decreased GFR (<60mL/min)
What is the easiest way to know if a patient has CKD?
By monitoring decreased GFR using MDRD.
Can also assess protein in urine because that typically doesnt happen in AKI
Stages of CKD
1- Normal, GFR>90mL/min 2-Mildly decreased, GFR 60-89 3- Mild to moderate decrease, GFR 45-59 Moderate to severely decreased, GFR 30-44 4- Severe decreased GFR, GFR 15-29 5- Kidney Failure, GFR <15 or dialysis
What are the common causes of ESRD?
Diabetes and HTN are the main causes
Can also be because of glomerulonephritis
CKD susceptibility risk factors
Diabetes, HTN, Older age (>55), family history, racial or ethnic minority
Progression factors of CKD
higher levels of proteinuria Higher BP Poor glycemic control Smoking Hyperlipidemia Drugs Obesity
CKD complications
CVD
Anemia
Altered bone and mineral metabolism
Pathophysiology of CKD
Loss of nephron mass-damage due to one or more of the progression factors
Glomerular capillary HTN- mediated by AT II
Proteinuria- Both a marker of damage and can lead to further damage as proteins are toxic to tubular cells
If a patient had a recent infection, symptoms with urination, a skin rash, or arthritis, what might be the potential problem?
Post-step glomerulonephritis
UTI
Lupus
If a patient has chronic disease such as CHF, cirrhosis, diabetes, HTN, what might be the potential problem?
Prerenal CKD or CKD
If a patient has a family history, what might be the potential problem?
Polycystic kidney disease
What lab values should you measure for CKD patients?
Estimated GFR (at least annually)
BP
Urine examination (at least annually)
-Albumin:Cr ratio (UACR) in early morning urine
sample(Albuminuria if >30)
-Examination for casts, sediment, etc.
Imaging studies
What is progression of CKD defined as?
A drop in GFR more than 5mL/min/year
What are common CKD complications?
Anemia, HTN, Vit D deficiency, acidosis, hyperphosphatemia, hyperparathyroidism
What are interventions of CKD that can delay progression?
ACE-Is, ARBs, BP control, blood glucose control
How do ACE-Is and ARBs delay the progression of CKD?
They lower systemic blood pressure, thus lowering glomerular capillary blood pressure and protein filtration rate. They also reduce AT II mediated cell proliferation and fibrosis.
This is accomplished in very low doses.
What is the evidence of ACE-Is and ARBs in delaying progression of CKD?
Should be used if UAE >30mg/day with diabetes
Should be used in all CKD pts with UAE >300mg/day
Patiromer (Veltassa)
Non-absorbed cation exchange polymer (K+ binder, exchanges for Na)
Used in patients with chronic hyperkalemia associated with ACE/ARB use
8.4g QD- Space out from other oral medications by 3 hours
May cause constipation or diarrhea
Sodium Zirconium Cyclosilicate (Lokelma)
Used in patients with chronic hyperkalemia associated with ACE/ARB use.
Use this or Patiromer (Not both)
10mg TID- space out from other medications by at least 2 hours
May cause edema
What do we do if Cr increases more than expected when a patient is on an ACE or an ARB?
If increased 30-50%, reduce dose
If increased >50%, D/C
This is a dose related effect
Can ACE and ARBs be used together?
No
Too high of a risk for hypotension, hyperkalemia, and decrease in kidney function.
This combination could cause an AKI on top of a patients CKD.
ACE-Is and Aldosterone blockers in CKD
Avoid combination except in CHF patients because of the high risk of hyperkalemia
Diuretics in CKD
Generally necessary in most CKD patients to help control fluid volume and BP
Most CKD patients have hypernatremia so diuretics reduce the Na levels.
Diuretics work synergistically with ACEe/ARBs by activating RAAS and promoting fluid retention
When do you use which diuretic in CKD
Thiazides if CrCl >30ml/min
Loops for CrCl <30ml/min
Cautious use of K-sparing diuretics especially if pt is on an ACE/ARB or has CrCl <30ml/min
Overdoing diuresis can lead to decreased GFR
What electrolytes do you monitor for with diuretic use?
Hypokalemia- loop and thiazide Hyperkalemia- K sparing Hypomagnesemia- Loop Hypocalcemia-Loop Hypercalcemia- Thiazide
What are additional antihypertensive options for CKD?
Beta-blockers- Not helpful or harmful in CKD but proven CVD benefits. Must counsel patient if diabetic. Do not use or adjust dosage of atenolol (renally cleared) Non-DHP CCBs (Verapamil, Dilt)- reduces proteinuria Avoid DHPs (nifedipine, Amlodipine) unless out of options and avoid aliskiren because of hyperkalemia.
What constitutes uremia?
Having baseline symptoms chronically
Nutrition considerations for CKD
Eat low K and Phos foods
Keep salt intake <2g/day
Low sugar, low carb, normal BMI
What is the general approach of HTN and CKD?
Goal is to prevent ESRD and CVD
Most patients will be on 2 or more antihypertensives
Monitor BP and level of proteinuria
Side effects are more likely in CKD pts
What did the SPRINT trial teach us?
CKD is worsened if BP gets too low.
Because of this trial we now have a goal BB for CKD+HTN pts <130/80 (ACC guidelines)
If urine albumin is >300 in a HTN/CKD pt, what do you do?
Maximize ACE-Is when protein is in urine.
Give ACE-Is across the board if protein in urine.
May have to use additional HTN medications if blood pressure is not <130/80
Hemoglobin A1C
Measures long-term diabetes control.
Keeping A1c <7% slows the development of complications
Macrovascular complications-CAD, stroke
Microvascular complications- Nephropathy, retinopathy, neuropathy
Medications in diabetes
Insulin- renally cleared (be cautious with dosing)
Oral agents:
sulfonylureas- cleared by kidney (Glipizide is only one w/o active metabolites so it is preffered)
Metformin- if drug and metabolites accumulate it causes lactic acidosis
Diabetic nephropathy
Generally occurs with 10 years of poorly controlled diabetes.
Has persistent albuminuria
20-40% of diabetic patients develop CKD
Pathophysiology of diabetic nephropathy
Mesangial cell hypertrophy (reduced GFR) Advanced glycation end products (leads to sclerosis and fibrosis of glomerulus) Oxidative stress Damaged glomerular filtration barrier Tubulointerstitial injury RAAS
Screening of diabetic nephropathy
Urine albumin excretion tested annually
If >30, repeat 2 more times within 3-6 months
Positive test if 2/3rds are positive
SCr annually (calculate GFR)
Treatment of diabetic nephropathy
Intensive glucose control to slow progression of albuminuria (A1C <7%)
Control BP <130/80 with ACE
Control albuminuria- ACE or ARB
Smoking cessation
Protein restriction (0.6-0.8g/kg/day)
DM alone is not an indication for ACE/ARB, must also have CKD
Tight glucose control in CKD
Blood sugar goals
Pre-prandial 80-140mg/dL
Post-prandial <180mg/dL
A1C goal <7%
GLP-1 agonists and SGLT2 inhibitors in CKD
Both classes reduce CV events
Incidence of CVD in CKD patients
> 50% of dialysis pts have coronary calcifications
CHF is the leading CV condition you will see (HTN+volume overload)
40% increase of stroke
Pts should be on high-intensity statin and ASA
Cardiac monitoring for CKD
BNP
-BNP is not accurate when GFR <60mL/min
Troponins
-Not accurate when GFR <60mL/min
What is the significance of proteinuria?
Results from injury to glomerular filtration (marker of kidney disease)
Marker of systemic injury (increased CV risk)
Dyslipidemia in CKD
All CKD patients >50 should receive a high-dose intensity statin
Avoid statins in dialysis patients
The increased risk of proteinuria with statins is dose related so rosuvastatin must be limited to 10mg/day in stages 4 and 5
What did the SHARP trial teach us?
Do not give statins in dialysis pts
Eze/simv combo did not reduce events
Polycystic kidney disease (PKD)
Genetic autoimmune disorder
Causes fluid filled cysts on both kidneys which cause a dramatic increase in size
2 forms- autosomal dominant and recessive (infants)
Symptoms of PKD
HTN Family history heart problems or strokes kidney stones constant or intermittent pain in back or side hematuria
Treatment of PKD
Manage pain
Treat infections
Treat HTN- goal <130/80
Prepare for ESRD (dialysis or transplant)
Tolvaptan has some data that shows that it may slow the increase in renal volume and decline in renal function
What are the methods of urine analysis?
Random (no warning or prep)
Clean catch, midstream (1st half discarded, second half collected and evaluated)
Bladder catherization- avoid if possible
Suprapubic needle aspiration- Needle directly into bladder to catch urine
24 hr urine collection- cumbersome and inaccurate
What are the definitions of polyuria, oliguria, and anuria?
Polyuria-excess urine production
Oliguria- Urine production <500mL/24 hours
Anuria- Urine production <50mL/24 horus
What do the following odors of urine mean? Sweet or fruity, foul, strong
Sweet or fruity- Glucose, ketones
Foul- infection
Strong- dehydration, foods
What drugs change the color of urine?
Nitrofurantoin- brown
Amitriptyline- Green/blue
Phenazopyridine- orange
Rifampin- Red
What is the purpose of the urinalysis?
To reveal diseases that may go unnoticed. Glomerulonephritis Hypertensive nephropathy Renal failure Infection Diabetes
Why do hypertensive patients get a urinalysis every year?
Because it takes 1/2 of the nephrons to be damaged in order to affect the creatinine.
How do infections affect the urine pH?
They increase it (more basic)
Specific gravity of urine
Normal range (1.002-1.035)
Measures urine density
Ability of the kidney to concentrate urine
High specific gravity=Dehydrated patient=Hypovolemia
High specific gravity=kidney stones
Protein in urine
Normal is negative or trace Primarily albumin Protein is filtered at the glomerulus and reabsorbed in the proximal tubule. If there is protein in the urine, there has been tubular damage. Microalbuminuria- 30-300mg/day Macroalbuminuria- >300mg/day
Glucose in urine
Normal is negative
Usually correlates with blood glucose >180mg/dl, because it “spills” into the urine.
Ketones in urine
Normal is negative
Spilled into the urine when the body cannot utilize glucose or lack of glucose intake.
Find in patients with life-threatening hyperglycemia (diabetic ketocacidosis)
Blood glucose 800-1000mgdL or starvation
Bilirubin in urine
Normal is negative
If present, a marker of liver disease
Blood in urine
Normal is negative
Called hematuria
Correlates clinically with an injury to the kidney (UTI, traumatic sample, injury, stones)
Can also be caused by mygoglobinuria from rhabdomyolysis
Nitrites in urine
Normal is negative
Bacteria in the urine is converted into nitrates, which then get converted into nitrites.
Presence of nitrites in urine signals the presence of gram negative organisms in the urine.
A negative result does not rule out a UTI, but a positive result indicates a UTI
Leukocyte esterase in urine
Normal is negative
Positive test detects the presence of lysed white blood cells in urine.
Indicates infection
Red blood cells in urine sediment
Normal 0-2/hpf Hematuria A marker of: Glomerular disease Tumors that affect urinary tract Kidney trauma Renal infarcts Infections Traumatic catheterizations Renal stones Nephrotoxins
White blood cells in urine sediment
Normal 0.-3/hpf
Termed pyuria
Marker of infection, glomerulonephritis, interstitial nephritis, inflammation, or rejection of transplant
Squamous epithelial cells in urine sediment
If present, likely contaminated with skin flora
Bacteria and yeast in urine sediment
Should not be present, if present look at nitrates, WBCs, etc.
Correlates clinically with s/s of a UTI
Can be caused by asymptomatic bacteruria, chronically catheterized patients, pregnancy, or be a contaminated specimen.
Culture and Sensitivity (C&S) is next step
Significant bacteruria >100,000 CFU of one organism needs to be addressed
Repeat if only yeast because contamination likely occurred.
Casts in urine sediment
Means any nephrons have been damaged
Collection of protein, cells, and debris
Formed in distal tubule and collecting duct
Important marker of kidney damage
Types of casts
Hyaline- most common, marker of kidney disease
Red cells- hematuria, glomerulonephritis (GN)
Granular- significant renal disease, “muddy brown”, ATN or GN
Epithelial- interstitial nephritis, ATN
Waxy- degenerated granular casts, marker of significant CKD
Crystals in urine sediment
Formed by precipitation of urine salts subjected to changes in pH or concentration
Calcium- kidney stones
Urate- hyperuricemia
Both could indicate post-renal obstruction
Some drugs (sulfonamides) may crystallize in the urine so you have to take with water.
UA markers of renal disease
Protein, blood/hematuria, casts (hyaline or granular)
UA markers of infection
Nitrites (gram neg), leukocyte esterase, pyuria/WBC, bacteria if above are found and symptomatic
What does mucous in UA indicate?
Contaminated specimen
Azotemia
Accumulation of nitrogenous wastes in blood (increased BUN)
Uremia
Constellation of symptoms associated with azotemia
Uremic symptoms drive treatment recommendations
Oliguria
Urine output <500ml/day
Signal high risk of morbidity and mortality
Anuria
Urine output <50ml/day
Signal high risk of morbidity and mortality
Nonoliguria
Urine output >500ml/day
Urine output is normal, but patient has AKI
What is the KDIGO definition of AKI?
Rapid (hours to days) deterioration of renal function.
This can be shown by:
-Increase in creatinine of >/=0.3mg/dl in <48 hours
OR
-Increase in creatinine to >/=1.5 times baseline which is presumed to have occurred in the prior 7 days
OR (less commonly used)
-Urine output <0.5mg/kg/hr for 6 hours. The urine output is more immediately affected by AKI than SCr.
What might future definitions of AKI include?
Tubular injury and kidney stress biomarkers
What is the difference between AKI and CKD?
AKI- abrupt onset, often reversible if treated early
CKD- the end result of irreparable damage to the kidneys. Develops slowly over the course of years. Technically defined as greater than 3 months of chronically decreased GFR. You have to lose 1/2 of your nephrons before CKD occurs.
Epidemiology of AKI
2-20% of hospitalized patients
(20-60%) ICU patients
Associated with significant morbidity and mortality
Mortality of 15-40% if acquired in hospital-prevention is key!
Why do so many ICU patients develop an AKI?
The body adapts to serious illness by bringing blood to the brain and heart.
Some patients in ICU are given pressors (Norepinephrine) to increase BP and they cause AKIs because they are very nephrotoxic. Sacrifice kidneys to save the patient.
What constitutes the syndrome of AKI?
Accumulation of nitrogenous waste products (Increased BUN and Cr)
Increased SCr
Derangement of extracellular fluid balance
Acid-base disturbance
Electrolyte and mineral disorders (hyperkalemia and hyperphosphatemia)
What are the symptoms of AKI?
Decreased urine output (70%) Edema (especially lower extremity) Mental status change (uremia) Heart failure N/V (uremia) Pruritus (uremia) Symptoms that correlate with any associated electrolyte disorders
What constitutes uremia?
Renal failure Mental status changes (lethargy, confusion) Muscle weakness Anorexia Dysgeusia (metallic taste) Pericarditis (can cause fatal arrhythmias) Neuropathy N/V Pruritis Dyspnea Pulmonary edema
What are the types of AKI?
Prerenal, intrarenal, postrenal
What are the types of intrarenal AKI?
Vascular, glomerular, tubular, interstitial
Prerenal azotemia
Caused by decreased blood flow to the kidney. This causes decreased filtration of toxins and increased SCr and BUN (azotemia)
The integrity of renal tissue is preserved initially so it may be reversible! It causes ischemic damage if not corrected.
Which patients are most likely to have prerenal azotemia?
Patients with dehydration and hypotension
What factors increase the susceptibility to renal hypoperfusion?
- Structural changes in arteries (old age >75)
- Chronic HTN or acute hypotension
- CKD
- Reduction in vasodilatory prostaglandins
- Failure to vasoconstrict the efferent arterioles (ACE/ARB)
- Renal artery stenosis
- Intravascular volume depletion (dehydration, CHF, liver disease)
Why are elderly patients (>75) more susceptible to renal hypoperfusion?
Elderly people have decreased renal blood flow and their SCr may not increase because they have lower muscle mass.
Which medications cause an impaired compensatory mechanism?
NSAIDs- suppress afferent arteriole vasodilation that body would desire to increase renal blood flow
ACE/ARBs- suppress the efferent vasoconstriction that body would desire to maintain adequate perfusion pressure inside the glomerulus
Signs/Symptoms of hypovolemia
Decreased blood pressure Increased HR Orthostasis Pallor, dry mucous membranes BUN:SCr ratio increased FENa
Main categories of prerenal AKI
decreased circulatory volume (hypovolemia) diminished cardiac output (HF) hypotension impaired compensatory regulation Systemic/renal vasoconstriction Renovascular obstruction
What causes decreased circulatory volume, and thus a prerenal AKI?
Dehydrated patient Renal losses- diuretics, diabetes Skin losses- sweating, burns Third spacing due to hypoalbuminuria- cirrhosis Hemorrhage
plasma BUN:Cr ratio
Normal ratio is 20:1
In pre-renal AKI- >20 usually. Rises faster than usual due to more reabsorption
If BUN and SCr are elevated, but the ratio is still close to 20, then this is indicative or a chronic renal disorder.
FENa
Fractional excretion of sodium
FENa=(Urine Na+plasma Cr)/(Plasma Na+ Urine Cr) x 100
FENa <1%= prerenal AKI ( body is trying to preserve Na in the face of volume depletion)
FENa>2%= acute tubular necrosis (body cannot preserve Na because tubules are damaged)
What kind of medication will elevate urine sodium and make FENa calculation innacurate?
Loop diuretics (furosemide)
Risk factors for ACE/ARB induced AKI
Reduced renal blood flow- CHF, bilateral renal artery stenosis
Volume depletion- dehydration, excessive diuresis
Hold ACE/ARBs if patient is volume depleted!
What should you do if SCr rises with ACE/ARB?
It is expected to rise up to 30%
It should stabilize, but if it doesn’t D/C medicine and correct underlying condition (rehydration)
Consider captopril if you still want an ACE but are unsure of renal effects. It has a very short 1/2 life.
Effects of ACEI-s on the kidneys
Protects the kidney by decreased pressure inside the glomerulus
- Reduces damage to glomerulus and reduces protein spillage in urine
- This is why ACE-is are drugs of choice for diabetics and those with hypertensive kidney disease
May decrease renal function by decreasing pressure inside glomerulus
-Decreases filtration of creatinine which raises SCr levels
Effects of NSAIDs on the kidneys
Inhibition of cyclo-oxygenase leads to vasoconstriction of afferent arterioles
This reduces GFR
This sets up patients who are already at risk of reduced GFR to go into renal failure- elderly, CHF, hypotensive, dehydration
What are the causes of systemic/ renal vasoconstriction that can cause a prerenal AKI?
pressors- vasopressors
General anesthesia
Afferent vasoconstriction- sepsis, cyclosporine, tacrolimus, radiocontrast dyes
Why do NSAIDs increase the risk of AKI?
afferent vasoconstriction
What is hepatorenal syndrome?
It is found in patients with liver failure because liver failure causes renal failure
Portal HTN causes ascites and renal vasoconstriction
Cyclosporine/Tacrolimus
Afferent constrictors
Used to prevent rejection of implanted organs
Can have acute and chronic toxicity
Renal function improves rapidly following dose reduction.
Prevention- closely monitor levels, use CCBs to manage HTN (dilate afferent arterioles)
Intrarenal AKI- vascular
Clot in renal artery
Can be caused by thromboembolic disease, angioplasty, severe CHF, AFIB, etc.)
Bilateral 15-30% of time
Symptoms- flank pain, tenderness
Tx- anticoagulant medications if unilateral, surgery if bilateral
Could also be caused by high cholesterol
Renal artery stenosis
Correlates with poor cardiac health
Consider RAS when there is an abrupt onset of HTN in a young pt or there is refractory HTN
Avoid ACE/ARB
Treat surgically via angioplasty
Acute tubular necrosis (ATN)
Intrarenal tubular AKI
Slow to resolve
Prolonged prerenal azotemia of any cause
Ischemic- due to lack of blood flow and O2 supply (sepsis, surgery)
Nephrotoxic- endogenous (body is creating)
Myoglobin, myeloma, uric acid
What exogenous nephrotoxins can cause ATN?
Aminoglycosides Amphotericin B Cisplatin and carboplatin Cyclosporine, tacrolimus Intratubular drug precipitation Rhabdo (statins, cocaine) Iodinated contract dyes
What do you typically see on a UA with ATN?
Granular casts (Muddy brown)
Aminoglycosides
Cause ATN by proximal tubule cell damage
Examples: gentamycin, tobramycin, amikacin
These abx are used in life-threatening situations and the tx plans are very individualized.
Generally see ATN after 5-10 days (SCr will rise)
What are the risk factors for aminoglycoside toxicity?
Large cumulative doses and multiple daily doses
Use of furosemide or other loops in conjunction
Pre-existing renal disease, elderly, sepsis, dehydration
Aminoglycoside considerations
Monitor SCr daily and d/c if it rises quickly
Consider inhaled formulation if resp infection
Recovery from ATN takes about 3 weeks, but some nephrons never recover
Amphotericin B
Broad spectrum antifungal agent that is used when nothing else is available
Causes ATN in the proximal and distal tubules
Afferent vasoconstriction and ischemic injury
If you have to run it- run it slowly over 24 hours because the amount of exposure is reduced.
Amphotericin B considerations
Use liposomal formulation if you can (costly)
Associated with substantial losses in Mg and K
Prevention- avoid cumulative exposure, avoid nephrotoxins, hydrate
Cisplatin and Carboplatin
ATN (proximal)
Elevations in SCr generally appear 10-12 days after initiation of therapy and recover by day 21
Prevent toxicity- reduce dose/frequency, use carboplatin over cisplatin, pre-hydrate with NS, Amifostine to help direct drugs to cancer cells
Intratubular precipitation
Tumor lysis syndrome- elevated uric acid levels often due to chemotherapy
Intratubular drug precipitations- sulfonamides, methotrexate, acyclovir, triamterene (take with H2O)
Rhabdo- statins, cocaine
Instrinsic AKI rhabodomyolysis
Mech- myoglobin from muscle breakdown precipitates in the tubules and obstructs them
Causes- trauma, toxins/drugs (statins), seizures, infections
Treatment- hydration and urine alkalization with sodium bicarb, Maintain UOP at 300ml/hr
You will be able to tell if the urine is clear of myoglobin by color (myoglobin makes urine red, purple, or dark brown)
Acute interstitial nephritis (AIN)
Allergic hypersensitivity response
fever, rash, eosinophilia are common
UA- may have eosinophils, hematuria, pyuria, and arthralgia
Can occur one day to several weeks after exposure
Often caused by drugs
Drugs that commonly cause AIN
Allopurinol Quinolones (cipro) Furosemide (and other loops) NSAIDs Penicillin Phenytoin Sulfa drugs Thiazides PPIs
Usually reversible if caught on time!
Chronic interstitial nephritis
Often caused by NSAIDs, lithium, cyclosporine/tacrolimus
Delayed, irreversible damage
Contrast-Induced nephropathy (CIN)
AKI occurring w/in 48 hours of exposure to IV contrast
Generally find hyaline and granular casts on UA
Risk factors for CIN
Pre-existing renal disease HTN CHF pre-procedural hypovolemia Nephrotoxic agents Intra-procedural hypotension Age >75