Kidney's Flashcards
What are the Functions of the kidney’s? (3)
Excretory:
- filtration, secretion, excretion
Endocrine:
- renin, prostaglandins, kinins, erythropoeitin
Metabolic:
- Vit D activation, gluconeogenesis, insulin metabolism
What excretory functions do the kidneys have?
REgulate fluids, electrolytes, and acid-base balance
Remove metabolic waste products and foreign chemicals from blood for urinary excretion.
Explain the filtration process of the kidneys.
Blood enters glomerulus through afferent arteriole
Blood filtered by hydrostatic pressure through capillaries that for from the glomerulus into the bowman capsule
Blood leaves kidney through efferent arteriole
What is the filtrate composed of?
~20% of plasma entering glomerulus, mainly fluids, electrolytes, small molecules
Excludes proteins and large molecules
What arteriole does unfiltered blood enter in the kidneys?
Afferent
What arteriole does filtered blood leave the kidney from?
Efferent
What are some examples of filtrates in the urine?
Glucose
Electrolytes
AA’s
Water
Urea
Uric acid
Creatinine
Protein (some not alot)
What is reabsorption?
Movement of substances out of rena tubules back into the blood capilaries
What is secretion?
Substances move out of the blood and into the tubules to be converted into urine
How are substances secreted?
Active transport or
Difusion across the membrane
Which organs regulate acid-base balance? How?
Kidneys: hydrogen ion secretion, bicarbonate reabsorption, phosphate and ammonia buffer systems
Lungs: alveolar ventilation of CO2
What is acidosis?
In response to excess acid, kidneys reabsorb all filtered bicarbonate and produces new bocarbonate
What is alkalosis?
In response to little acid, kidneys excrete bicarbonate to restore H+ [ ] to normal
What kinds of waste do the kindeys excrete?
Waste products from protein metabolism and muscle contraction,
Certain drugs
What hormones to the kidney’s produce?
BP control
RBC production
What BP control mechanisms are in place?
RAAS
Antidiuretic hormone
Atrial natriuretic peptide
Where is renin released from?
renal juxtaglomerular cells b/c of decreased BP
What can renin indirectly lead too?
Vasoconstriction amd Na/ water rentention
What are the effects of Angiotensin II?
Kidney’s: Na retention and water retention
Brain: release corticotropin and adiuretin, thirst
Adrenals: Aldosterone production increased
Blood Vessels: Vasoconstriction and increased BP
What arteriole does ANG II vasoconstrict?
Efferent
What do prostaglandin E2 and I2 do?
Cause vasodilation especially at the afferent arteriole to increase renal perfusion
Promotes secretion of renin
When are prostaglandins produced (E2 and I2)
In response to decreased blood flow
Where is adosterone secreted from?
the adrenal cortex in response to ANG II
What does aldosterone stimulate?
Tubule reabsorption of sodium
Indirectly increases K excretion, and H+
Where is ADH secreted from?
Posterior pituitary in response to increased Na blood levels/ low blood volume
What does ADH do?
promotes water reabsorption by increasing permeability of collecting ducts.
Where is ANP stored?
Right atrium of the heart
When is ANP released?
In response to increased stretch of the heart muscle; indicative of fluid overload
Is elevated in HF
What does ANP do?
Opposes RAAS by causing vasodilation and increased renal excretion of sodium
(Opposite of aldosterone)
What does erythropoeitin do?
Stimulates production of RBCs
What % of erythropoeitin is produced by the kidney’s?
90%
What area of the kidney produces erythopoetin?
Peritubular interstitial cells
What does a lack or deficiency of erythropoeitin lead to in CKD?
Anemia
What enzyme in kidney turns calcidiol to calcitriol?
1-alpha-hydroxylase
What upregulates /dowregulates to production of calcidiol to calcitriol?
Up PTH, low Phosphate
Down: Calcitriol
What is gluconeogenisis?
Creation of glucose from AA’s
Most occurs in liver but, some occurs in cortex of kidneys
Why do we check renal function? (3)
Monitoring and recognizing CKD
- effects of drugs on slowing progression
- predict time to onset of ESRD
- Evaluating riskof complications
Adjust doses of meds excreted by the kidneys
Monitoring nephrotoxic medications
What protein do we use to measure GFR?
Creatinine
What happens to SCr when GFR is reduced?
Increases
What is the equation used for classifying the severity of kidney disease?
CKD-EPI
What equation is used for making renal dose adjustments?
Cockcroft-Gault
T or F, the CKD-EPI equation is used to estimate kidney function in a pt receiving dialysis.
False
What are some limitations of the equations used?
Factors affecting Cr generation –> body size, race, muscle mass, diet
Factors affecting tubular secretion of Cr
Factors affecting extra renal elimination of Cr
What changes were made to the eGFR calculations in 2021?
Race was removed from equation
What is the difference between indexed/normalized and non-indexed eGFR?
Indexed: BSA factored in (mL/min/1.73m^2)
Non-indexed: adjusted according to the patients BSA (mL/min)
When do we caution using non-indexed eGFR calculations?
In morbidly obese b/c can lead to ODs
Why does the measurement of BUN underestimate GFR?
Reabsorbed by kidneys
What happens to BUN in renal impairment?
Increases
What other factors can affect BUN?
Dietary protein
GI bleeding
Hydration status (high in dehydration)
What does persistent increase in protein in the urine indicate?
Marker for kidney damage
Is proteinuria good?
NO –> more protein = Glomerular damage = renal impairment
SHould there be any albumin in the urine?
Yes, small amounts is normal
What is the ACR?
Albumin : creatinine ratio
Describe Normoalbuminuria
A1: <3mg/mmol normal or mildly increased
Describe Microalbuminuria
A2: 3-30mg/mmol moderately increased
Describe macroalbuminuria
A3: >30mg/mmol severely increased
What are some potential causes of transient albuminuria?
Recent major exercise
UTI
Febrile illness
Decompensated CHF
Menstruation
Acute sever elevation of BG
Acute severe elevation of BP
What does presence of eosinophils in the urine indicate?
Interstitial nephritis
What is the definition of AKI?
A sudden decline in renal function (hours-days) as evidence by changes in SCr, BUN, and urinalysis
T or F. CKD-EPI is used to estimate kidney function in a pt suspected of experiencing an AKI.
False
What conditions can AKI be defined as? (3)
Increase in SCr by > 0.3mg/dL within 48hrs
Increase in SCr >1.5 x baseline presumed to have occured in last 7 days
Urine volume <0.5mL/kg/h for 6h
Define ANuric
less than 50mL/day urine output
DEfine Oliguric
Less than 500mL/day urine output
Define non-oliguric
greater than 500mL/day urine output
R in RIFLE?
Risk: SCr increase 1.5x, GFR decrease >25%, <0.5mL/kg/hfor >=6h urine output
I in RIFLE?
Injury: SCr increase 2x, GFR decrease >50%, <0.5mL/kg/hfor >=12h urine output
F in RIFLE?
Failure: SCr increase 3x, GFR decrease >75% or SCr >= 354umol/L with acute increase >=44umol/L
Anuria for >=12h
L in RIFLE?
Loss of function for > 4 weeks
E in RIFLE?
ESRD: loss of function for > 3 months
AKIN Stage 1 criteria?
SCr increase >=27umol/L or 1.5-2x, Urine output of <0.5mL/kg/h for >=6 hours
AKIN Stage 2 criteria?
SCr increase >2-3x, Urine output of <0.5mL/kg/h for >=12 hours
AKIN Stage 3 criteria?
SCr increase > 3x or SCR .= 354umol/L with acute increase of >=44umol/L, Urine output of <0.3mL/kg/h for >=24 hours or Anuria for >12 hours
After developing AKI how long may it take to see an increase in SCr?
up to 4 days
What is criteria all based on? What do you need to know?
SCr, need to know pts baseline.
What are the clinical presentations of AKI?
Most are asymptomatic
can present with:
- dehydration
- Malaise, anorexia, N&V, pruitis
- Severe abdominal or flank pain
- Decreased force of urine stream
Cola-coloured urne
- Excessive foaming in urineSudden wt gain
- edema
What are some risk facors for AKI?
Anything tha decreased blood flow to kidneys
Pre-existing renal dysfunction
Drugs (20% of cases)
What are the characteristics of Pre-renal AKI?
Most common AKI (60%)
Hypo-perfusion –> not enough blood flow to kidneys
Kidneys are healthy
Can be decreased perfusion b/c:
- intravascular volume depletion (hemorrhage, dehydration, burns, diuretic therapy)
- decreased effective circulating volume (HF, cirrhosis)
- Hypotension
- decreased glomerular flitration pressure (ACEi/ARBS, NSAIDs)
What are the characteristics of Intrinsic AKI?
25-35% of cases
Results from direct damage to the kidney
- ischemia, toxins, or disease
What are the 4 main types of intrinsic AKI?
- acute tubular necrosis: endogenous(myoglobin) or exogenous(toxins, ischemia)
- Acute interstitial nephritis: idiopathic hypersensitivity immune reaction to drugs (NSAIDs, penicillin) infection
- Acute glomerulonephritis: post strep, antigen-antibody complexes
- Vascular kidney injury: renal artery stenosis, HTN
What are the characteristics of Post-renal AKI?
<5% of cases
Obstruction to urinary flow anywhere in the urinary tract
Causes:
- nephrolithiasis (kidney stones)
- prostate enlargement
- Cervical cancer tumors
- Drugs that crystallize
What do you use to diagnose AKI?
History
Lab data:
- SCr
- Urinary Na [ ] (decrease with pre-renal AKI, Increase with tubular damge)
- urinalysis
- SOmetimes : ultrasound(renal), kidney biopsy
What are the treatment goals of AKI?
Prevent further renal injury
Minimize extra-renal complications
Facilitate recovery of renal function back to baseline
Treatment for Pre-REnal failure?
Hydration with IV fluids
d/c diuretics of hypovelimic
BP support with vasopressors (dopamine, norepinephrine, vasopressin)
Fluid removal in volume overload states w/ diuretics
Stop drugs that impair kidney function/ urine flow
Treatment for Intrinsic renal failure?
D/c offending agent
Manage underlying autoimmune disease
Treatment for Post-renal failure?
Catheter to restore urine flow
identify and remove obstruction
adequate hydration when giving drugs with potential to crystalize
What are the number for mild-moderate K elevation? Severe?
5.1-7 mmol/L
>7mmol/L
What can occur with sever hyperkalemia?
ECG changes –> Heart block, netricular tachycardia, death
Treatment for mild hyperkalemia?
Kayexalate (sodium polystyrene sulfonate) 15-60 g po BID-QID until K normalizes
Furosemide IV admin to increase urinary excretion –> need functioning kidneys
How does sodium polystyrene sulfonate work?
Exchanges Na for K which then gets eliminated bound to polystyrene sulfonate
Has a delayed effect –> not great for severe cases
Treatment for Severe hyperkalemia?
Calcium gloconate
TO drive K out of celss :
- Raid acting/ regular insulin +/- glucose depending on BG
- Sodium bicarbonate IV infusion (if metabolic acidosis present)
- Salbutamol via nebulizer (if pulmonary congestion)
Kayexalate to eliminate excess K from body
Dialysis if refractory
What does Calcium gluconate do?
Stabilizes myocardium –> protects myocardium, has no effect on K levels just used to avoid arryhmias
Effect is in a matter of minutes
Treatment for fluid overload?
Diuretics –> Furosemide +/- metolazone
Treatment for metabolic acidosis?
Sodium bicarbonate IV
When do you use dialysis for AKI?
AEIOU
Acidosis
Electrolyte abnormalities
toxic Ingestions
fluid Overload
Uremia
What is the leading cause of CKD ?
Diabetes (38%)
How many canadians live with CKD?
~4 million; 1/10
What % of pts living with CKD are managed in primary care
95%
What is CKD?
Progressive loss of function occuring over several months-years
What happens to the kidney architecture in CKD?
Normal kidney tissue gets replaced wirth fibrotic tissue
What are the 2 main causes of CKD?
Diabetes
Hypertension
At what GFR is CKD defined at?
<= 60 mL/min/1.73m^2 for 3 months+
with or without kidney damage
Can you be diagnosed with CKD without a decrease in GFR?
Yes;
kidney damage for 3+ months as evidenced by pathological abnormalities in blood or urine, or as seen by renal imaging
What ratio of of ACR is a marker for kidney damage (KDIGO)
> =3 mg/mmol
What are the riks of reduced GFR due to age alone?
Higher risk of AKI
Medication accumulation with reduction of GFR
REduced reserves in the event other comorbitites develop over time
GFR categories/stages of CKD?
G1: >= 90 (normal/ high GFR)
G2: 60-89 (mildly decreased)
G3a: 45-59 (mild/moderately decreased)
G3b: 30-44 (moderate-severely decreased)
G4: 15-29 (Severely decreased
G5: <15 (kidney failure: dialysis or transplant)
Albuminuria categories/ staging for CKD?
AER (mg/24hrs), ACR (mg/mmol)
A1: <30 , <3 (normal to mildly increased)
A2: 30-300, 3-30 (moderately increased)
A3: >300, >30 (severely increased)
What equation do you use to determine GFR estimate?
CKD-EPI
How do you stage CKD based on KDIGO?
Using both GFR and Albuminuria
What would someones staging be if they had a GFR of 55 and an ACR of 25? What would be there risk scale?
G3aA2 High risk
What would the staging be if someone had a GFR of 66 and an ACR of 32? What would be there risk scale?
G2A3
High risk
What are the clincial presentations of CKD how do they change with stage increase?
Symptoms are generally minimal in stage 1 and 2 and increase in incidences with stages 3 and 4
Low energy
Fatigue
Confusion
Edema
SOB
Pruitis
Foaming, tea-coloured, blood, or cloudy urine
What eGFR is usually managed with primary care?
Managed in consultation with a nephrologist?
30-59 (stage 3a/3b)
<30 (stage 4/5)
What are the goals of treatment for CKD?
Delay progression
CV risk reduction
Treat complications
Renal replacement therapies
Which CKD etiology’s tend progress more quickly ?
Diabetic nephropathy
glomerular diseases
polysyctic kidney disease
kidney disease in transplant recipients
Which CKD etiology’s tend progress more slowly?
Hypertensive kidney disease
tubulointerstitial diseases
What are non-modifiable factors of CKD progression?
African american race
Male gender
advanced age
Family history
What are modifiable factors of CKD progression?
uncontrolled HTN
Poor BG control
Proteinuria
Smoking
Obesity
What interventions can you use to delay the progression of CKD?
BP control
RAAS blockade
BG control in diabetes pts
Smoking cessation
Avoidance of nephrotoxic drugs
Does HTN cause or is caused by CKD?
Can be both
GFR decrease in untreated HTN /year? with BP <130/80?
~ 12mL/min/yr
~1-2mL/min/yr
BP target for pts w/ high BP and CKD (not dialysis pts)?
<120
Target BP for kidney transplant pts?
<130/80
What criteria were excluded from the SPRINT trial? (definetly know this she loves her studies)
Diabetes
What is a statement about BP in the 2020 HTN Canada guidelines say about strict BP control?
BP targets should be individualized at discretion of physician, considering all pt factors. Recommended to talk about potential benefits and adverse events related to lower systolic BP.
What are the clincial indications for SBP of <120? (AARF)
Age >75
Atherosclerotic plaque (CV disease)
Renal (CKD, porteinuria <1g/d, GFR 20-59mL/min)
Framingham risk score of >15%
What are some cautions and CI’s for SBP <120?
Limited or no evidence:
HF (LVEF <35%)
Recent MI (past 3 months)
Indication for a beta-blocker but not on one
Institutionalized elderly individuals
Inconclusive evidence:
Diabetes
Previous stroke
eGFR <20mL/min/1.73m^2 (includes dialysis and transplant)
CI’s:
Pt unwilling or unable to adhere to multiple meds
standing SBP<110
Inability to measure SBP accurately
Known secondary causes of HTN
What is a key takeaway from the SPRINT trial in relation to CKD progression?
Did not slow CKD progression (possibly slightly worsening, no impact on ESRD though)
List characteritics of a sutiable pt for SBP <120
Age> 50
w/o a high degree of comorbities
achieve BP w/o requiring a bunch of different meds
No issues with SE’s
List characteristics of a non-suitable pt for SBP <120
Age> 90, or living in nursing home
Requirment of >3 meds to get to target
At risk of falls from postural hypotenison
DBP of <60
SBP of 120-129
Severe HTN (>=180)
Those who fell the benefits are not worth the risks, cost, effort