Module 5 - Renal Flashcards
What are some renal function tests?
sCr (eGFR and ACR)
Urea (Uric acid)
What are some types of anemia in renal disease?
Hgb (Ferritin and iron)
%tSat (TIBC)
What are some functions of the kidney?
- Maintain H20 balance and plasma volume
- Maintain osmolality of body fluids
- Maintain acid-base balance
- Regulate ECF (extracellular fluid) ions
- Producing renin (RAAS)
- Production of erythropoietin
- Activation of vitamin D
- Excretion of waste products (urine)
What is the reason for the following lab abnormality:
Uremia (increased urea in blood)
retention of waste products
What is the reason for the following lab abnormality:
Metabolic acidosis (low pH, low HCO3)
can’t secrete H+ ions, can’t regulate bicarbonate (HCO3-)
What is the reason for the following lab abnormality:
Hyperkalemia (increased K+)
inadequate tubular secretion
What is the reason for the following lab abnormality:
sodium imbalances
kidneys cannot adjust excretion/retention
What is the reason for the following lab abnormality:
Phosphate and calcium imbalances (increased phosphate, decreased calcium)
kidneys cannot eliminate PO4 or reabsorb Ca2+, unable to activate vitamin D
What is the reason for the following lab abnormality:
Loss of plasma proteins (albuminuria) and glucose (glycosuria)
leaky glomerular membrane
What is the reason for the following lab abnormality:
Unable to concentrate urine (decreased urine Osmol)
impaired countercurrent system in loop of henle
What is the reason for the following lab abnormality:
Anemia (decreased Hgb, RBC, Act)
Inadequate erythropoietin production
List 3 ways to determine renal function
- Inulin or iothalamate clearance
- Serum creatinine and calculations
- 24-hr urine collection
What enzyme converts creatine to creatine phosphate (and vice versa) ?
creatine kinase
What is sCr (serum creatinine) ?
A nitrogen-containing, non-protein byproduct of muscle
sCr has an _____ relationship with kidney function
inverse
increased sCr = _____ renal function
decreased
Why does sCr increase in impaired renal function?
due to impaired excretion
sCr is used in equations to calculate ______ ________ and to estimate ____
creatinine clearance, GFRe
Why can elderly individuals have higher sCr?
due to decline in renal function
Why can elderly individuals have decreased sCr?
due to muscle wasting or malnutrition
_____ have higher muscle mass
males
What ethnicity has higher muscle mass?
African Americans
How does increased muscle mass affect creatinine production?
causes increased creatinine production
How does decreased muscle mass affect creatinine production?
less creatinine production
How does malnutrition affect serum creatinine?
malnourished patient may have low protein intake and may have muscle wasting
How does veganism/vegetarianism affect serum creatinine?
reflects relative protein intake
How do medications such as cimetidine, trimethoprim, probenecid, dronedarone, and tenefovir affect sCr?
increase sCr due to reduced tubular secretion of creatinine
How do medications such as methyldopa, cefoxitin, and flycytosine affect sCr?
decreases sCr because it interferes with the serum creatinine assay
What assumptions does the Cockcroft and Gault equation make?
- Assumes normal adult body weight (no extremes such as morbid obesity or cachexia)
- Assumes sCr is STABLE (not in acute renal failure or renal transplant patients)
-NOTE: Some institutions use 80 as a multiplier (vs. 88.4) due to standardization of sCr analysis (IDMS
What is eGFR?
Estimated Glomerular Filtration Rate:
-Using gender, age, ethnicity, and sCr, eGFR is calculated using the MDRD equation
When should MDRD equation be used?
should only be used in impaired renal function (<60 mL/min)
MDRD _______ renal function in patients with normal renal function
underestimates
If a patient has good renal function, what will the lab report?
> 60 mL/min
*it will not report a definite number
What drugs cause afferent vasoconstriction (which will decrease pressure, filtration, and GFR)?
PG inhibitions: NSAIDS
Direct constriction: cyclosporine, tacrolimus, contrast dyes, pressors
What drugs cause efferent vasodilation (which will decrease pressure, filtration, and GFR)?
ACEI/ARBs
Diltiazem, verapamil
What is urea? Describe it.
- Breakdown product of proteins (amino acids)
- 50% reabsorbed, 50% excreted in urine
Describe urea in dehydration
In dehydration, reabsorption of Na+, Cl-, and H2) occurs and therefore urea follows (increased urea)
Describe urea in renal disease
In renal disease, can’t eliminate urea (buildup) called uremia
Urea can be used with sCr to determine cause of ______ _________
renal abnormalities
What can cause elevated urea?
- High protein diet
- Renal disease
- Upper GI bleeding
- Dehydration
- Medications
What can cause decreased urea?
- Malnourished
- Vegetarian/vegan diet
- Fluid overload
- Liver damage
What can be used to determine the type of renal failure?
urea:creatinine ratio
When should urea:creatinine ratio not be used?
if both urea and sCr are within normal limits
Using Canadian measurements for urea:creatinine ratio, what does it mean if it is 100:1 ?
Pre-renal: decreased renal blood flow (more urea reabsorbed) or increased urea production
Using Canadian measurements for urea:creatinine ratio, what does it mean if it is 40-100:1 ?
Normal or post-renal: obstruction, therefore less outward flow and more urea is reabsorbed
Using Canadian measurements for urea:creatinine ratio, what does it mean if it is <40:1 ?
Intra-renal: damage within the kidney, can’t reabsorb urea (lowers ratio)
When do signs and symptoms of uremia develop ?
usually in ESRD (eGFR < 15 mL/min)
What are signs and symptoms of uremia?
- N/V
- fatigue
- anorexia/weight loss
- muscle cramps
- pruritus
- changes in mental status (confusion)
What are signs and symptoms of uremia in SEVERE cases?
- seizures
- coma
- cardiac arrest
- spontaneous bleeding
Are urea and uric acid the same thing?
no way man
What is increased urea called?
uremia
What is increased uric acid called?
uricemia
What is a buildup of uric acid called?
hyperuricemia
What does a buildup of uric acid lead to?
crystallization, inflammation and then gouty arthritis, renal stones, tophaceous deposits
What are some endogenous causes of uric acid build up?
- renal failure
- disorders associated with nucleic proteins (i.e. hemolytic anemia, cancer, psoriasis)
- endocrine disorders
- acidosis (lactic, keto, alcoholic)
- genetics
What are some exogenous causes of uric acid build up?
- medications
- diet (purine rich)
What are examples of drugs that increase uric acid through interfering with renal clearance of uric acid ?
Low dose salicylate, pyerazinaide, ethambutol, niacin, ethanol, cyclosporine, acetazolamide, hydrazine, furosemide, thiazide diuretics
What are examples of drugs that increase uric acid through increasing turnover rate of nucleic acids
Cancer chemotherapies (methotrexate, vincristine, 6-mercaptopurine, azathioprine)
Describe the Canadian goal of uric-acid lowering therapy
<357 umol/L
*if they have presence of top then <297 umol/L
How much should we lower uric acid each month to prevent a gouty attack?
59-119 umol/L per month
What is the concentration at which uric acid saturates extracellular fluids?
405 umol/L
During an acute gout flare, how do uric acid levels change?
may be low or normal due to the release of cytokines during the acute flare
When is the best time to determine uric acid levels?
> 2 weeks after subsidence of an acute gout flare
Monitor serum uric acid levels every ____ weeks during uric acid lowering therapy titration, then every ___ months once the target uric acid level is achieved.
2-5 weeks
6 months
How can kidney disease cause anemia?
- decreased erythropoietin
- decreased RBC production in bone marrow (erythropoiesis)
- causes anemia
What is transferrin saturation (%tSat) ?
- The percentage of transferrin (iron transport protein) that has iron bound to it
- Calculated using iron and TIBC from measured lab values
What is the normal %tSat ?
33%
In iron deficiency anemia, iron is ____
low
In iron deficiency anemia, TIBC is _____
high
In iron deficiency anemia, %tSat is ____
low
Anemia in renal disease:
Target for Hgb
110 g/L
Range 100-115 g/L
Anemia in renal disease:
Why do we monitor Hgb?
Higher hemoglobin levels (in the normal range) can increase the risk of stroke and CV events in renal disease patients. EPO also carries a cancer risk.
Anemia in renal disease:
How often do monitor hemoglobin?
Monthly if starting or changing EPO, every 3 months if stable on EPO therapy
Anemia in renal disease:
Target for %tSat
> 20%
Anemia in renal disease:
_____ supplementation is usually tried before initiating EPO in an attempt to increase hemoglobin. (Usually IV)
Iron
Anemia in renal disease:
Ferritin targets
ND-CKD and PD:
>100 umol/L
HD:
>200 umol/L
Anemia in renal disease:
Iron target
7-27 umol/L
Anemia in renal disease:
TIBC target
47-80 umol/L
Anemia in renal disease:
What are required to calculate %tSat ?
iron and TIBC
Anemia in renal disease:
When should you monitor ferritin, iron and TIBC?
Every 1-3 months
Takes time to build up iron stores
Bone Metabolism Abnormalities in renal disease:
Is phosphate usually high or low?
High
Bone Metabolism Abnormalities in renal disease:
Why is phosphate high?
cannot eliminate phosphate, PTH mobilizes phosphate from bone to blood
Bone Metabolism Abnormalities in renal disease:
Is calcium usually low or high?
usually low but can also be high
Bone Metabolism Abnormalities in renal disease:
Explanation for low calcium
cannot reabsorb calcium, low activated via D causes reduced calcium absorption in the gut
Bone Metabolism Abnormalities in renal disease:
Explanation for high calcium
due to longstanding high PTH with mobilization of calcium from bone to blood, or from calcium-containing phosphate binders (i.e. calcium carbonate)
Bone Metabolism Abnormalities in renal disease:
Is PTH high or low?
high
Bone Metabolism Abnormalities in renal disease:
Why is PTH high?
release triggered by low calcium levels and impaired vitamin D synthesis
Is phosphorus, calcium and PTH is high what do we do?
Add non-calcium containing phosphate binder; wait for PTH to come down by itself
ex. sevelamer
What do we do if phosphorous is high, calcium is low/normal and PTH is normal?
Add calcium-containing phosphate binder - especially if calcium is low
ex. calcium carbonate
What do we do if phosphorus is high, calcium is normal/low and PTH is high?
Add calcium-containing phosphate binder, add activated vitamin D to bring down PTH and increase calcium absorption in the gut
ex. calcium carbonate and calcitriol
What do you do if phosphorus is normal and PTH and calcium are high?
Add a calcimemetic. Decreases calcium and will bring down PTH
ex. cinacalcet
The kidneys are responsible for ___% elimination of potassium.
90%
Renal disease leads to accumulation of K+
How does insulin affect K+?
Insulin stimulates Na-K-ATPase pump to drive K+ into cells
How does epinephrine affect K+ ?
Stimulates B-receptors - activates Na-K-ATPase Pump
How does Aldosterone affect K+ ?
Promote the reabsorption of Na+ and H20 (in exchange for K+ which is excreted in the urine) in the distal tubule and collecting duct
How does acid-base status affect K+ ?
Complex process:
- metabolic alkalosis (decreases K+)
- metabolic acidosis (increases K+ but overall neutrality)
Describe aldosterone and potassium homeostasis
1) Increases effects of Na+K+ ATPase
2) Makes K+ channels so MORE potassium is excreted in the urine
3) Makes Na+ channels so more Na+ (and water follows) is reabsorbed into the blood (volume expansion and increased blood pressure)
Describe the treatment interventions for severe hyperkalemia (emergency treatment)
- Calcium gluconate 10% 500-1000mg (50-100mL) over 2-3 mins for cardiac stabilization
- Regular insulin 10-20 units with 25-50 g glucose
- Salbutamol 10-20 mg nebulizer or 1200 mpg (12 puffs) by spacer over 2 mins
- Hemodialysis (removes 25-50 mmol/K/hr)
Describe the treatment interventions for mild hyperkalemia
- Diuretics (thiazide if CrCl > 30 mL/Min, furosemide if CrCl < 30 mL/min)
- Kayexalate (sodium polystyrene sulfonate 15-30 g PO q4-6h
What is included in macroscopic analysis?
-color and appearance
What is included in microscopic analysis?
- cells (RBCs, WBCs)
- casts
- crystals
What is included in chemical analysis?
- specific gravity
- pH
- leukocyte esterase
- nitrite
- protein
- glucose
- ketones
- urobilinogen
- bilirubin
- blood (Hgb)
What is a urine dipstick test?
-Chem-Strip dipped in urine
Is a urine dipstick qualitative or quantitative ?
Semi-quantitative:
- Qualitative: positive/negative
- Quantitative: color represents a number or quantity of a specific parameter
List some possible abnormalities for a UTI that would show on a urine dipstick test
cloudy, WBCs, casts/blood, leukocyte esterase+, nitrite+
List some possible abnormalities for Diabetes that would show on a urine dipstick test
proteinuria, glycosuria, ketones )DKA_
List some possible abnormalities for renal disease that would show on a urine dipstick test
proteinuria, reduced specific gravity, renal stones (crystals)
List some possible abnormalities for hepatic disease/damage that would show on a urine dipstick test
urobillinogen increased, bilirubin
Describe microscopic urine analysis (for UTI’s)
1 mL urine centrifuged and the sediment is examined under a microscope
How will the following parameter be affected if they have a UTI:
RBC
> 1-2 cells/hpf
How will the following parameter be affected if they have a UTI:
WBC
large numbers (>30/hpf)
How will the following parameter be affected if they have a UTI:
Microorganisms
present
How will the following parameter be affected if they have a UTI:
casts
can be present in pyelonephritis
How will the following parameter be affected if they have a UTI:
crystals
positive or negative (indicates renal calculi)
How will the following parameter be affected if they have a UTI:
appearance, colour
cloudy, may be orange/red if blood present
How will the following parameter be affected if they have a UTI:
specific gravity
within normal limits
How will the following parameter be affected if they have a UTI:
pH
varies; may be acidic or alkaline, should be kept more acidic for treatment
How will the following parameter be affected if they have a UTI:
protein
negative or positive
How will the following parameter be affected if they have a UTI:
glucose
negative
How will the following parameter be affected if they have a UTI:
ketones
negative
How will the following parameter be affected if they have a UTI:
bilirubin
negative
How will the following parameter be affected if they have a UTI:
blood
positive (damage)
How will the following parameter be affected if they have a UTI:
leukocyte esterase
positive (esterase activity of leukocytes in the urine - fighting bacteria)
How will the following parameter be affected if they have a UTI:
nitrite
positive (bacteria reduce nitrates)
If the blood glucose level exceed the _________ capacity of the proximal tubule, glucose will appear in the urine
reabsorption
The blood level at which tubular reabsorption of glucose stops is about _____ mmol/L
9-10
Urine glucose is most common in patients with ______ (not used to diagnose)
diabetes
What do urine ketones indicate?
Uncontrolled Type 1 diabetes = diabetic ketoacidosis
*Deficiency of insulin causes derangement of carbohydrate metabolism which causes free fatty acids used as energy source
Other than diabetes, when can urine ketones occur?
can also occur in pregnancy, carb-free diets, starvation and alcoholism
What are some sings and symptoms of ketoacidosis ?
- headache/confusion
- seizures/coma
- nausea/vomiting
- ab pain
- hyperglycemia
- increased anion gap
- metabolic acidosis
What does excessive protein in the urine indicate?
the glomerulus is losing its filtering capability
What is ACR (albumin-creatinine ratio) used in the diagnosis of?
diabetic nephropathy and/or to monitor kidney disease progression
What urine sample is the best for ACR?
early morning urine sample