L.7 Renal Disease & Lab Investigation Flashcards
1
Q
What is Glomerular Filtration Rate (GFR)?
A
The flow rate of filtered fluid through the kidney
GFR is a key indicator of kidney function and health.
2
Q
What does Creatinine Clearance (CrCl) measure?
A
The volume of blood plasma that is cleared of creatinine per unit time
CrCl is a useful measure of GFR.
3
Q
What are the types of kidney function tests?
A
- Glomerular function tests
- Tubular function tests
- Blood tests
- Urinalysis
Each type assesses different aspects of kidney health.
4
Q
What do glomerular function tests include?
A
- Clearance tests (e.g. creatinine, urea, inulin, cystatin C)
- Glomerular Filtrate Rate (GFR)
- Proteinuria / Albuminuria
These tests evaluate the filtering ability of the kidneys.
5
Q
What do tubular function tests assess?
A
- Urine concentration tests
- Urine acidification tests
- Reabsorption tests
These tests evaluate the tubular function of the kidneys.
6
Q
What is measured in blood tests for kidney function?
A
- Serum creatinine
- Urea
- Electrolytes
- Acid-base balance
These tests evaluate the impact of kidney dysfunction on homeostasis.
7
Q
What does urinalysis assess in kidney function?
A
- Proteinuria
- Urine electrolytes
- Urine osmolality
- Urine output
- Dipstick test
Urinalysis evaluates the impact of kidney dysfunction on urine.
8
Q
What is the importance of kidney function tests?
A
- Detection of kidney disease
- Define the type of kidney disease
- Stage the severity of kidney disease
- Monitor progression of kidney disease
- Monitor response to treatment
- Dose medications appropriately
These tests are crucial for managing kidney health and treatment.
9
Q
True or False: Kidney function tests can monitor response to treatment.
A
True
Monitoring response to treatment is a key aspect of kidney function tests.
10
Q
Fill in the blank: Creatinine clearance is a useful measure of _______.
A
GFR
Creatinine clearance helps estimate kidney function.
11
Q
What types of kidney diseases can be defined using kidney function tests?
A
- Glomerular disease
- Tubular disease
- Interstitial disease
Identifying the type of kidney disease is essential for treatment.
12
Q
What do urine concentration tests evaluate?
A
Whether the patient can concentrate urine
This is a key aspect of tubular function.
13
Q
What is the purpose of monitoring renally excreted drugs?
A
To dose medications appropriately
Proper dosing is critical to avoid toxicity.
14
Q
What is assessed in urine acidification tests?
A
Whether the patient can acidify urine
This tests the tubular function of the kidneys.
15
Q
What does GFR stand for?
A
Glomerular filtration rate
16
Q
What are the four factors that GFR depends on?
A
- Renal blood flow
- Glomerular filtration pressure
- Glomerular filtration surface area
- Glomerular filtration membrane permeability
17
Q
What is required to calculate GFR?
A
Measurement of a substance in blood plasma and urine
18
Q
Define clearance in the context of renal function.
A
The volume of plasma that is completely cleared of a substance per unit time
19
Q
What factors influence the excretory rate of a substance?
A
- GFR
- Renal blood flow
20
Q
What criteria must a substance meet to determine GFR accurately?
A
- Freely filtered by the glomerulus
- Neither reabsorbed nor secreted by the tubules
- Not metabolised by the kidney
- Produced constantly by the body
- Ideally endogenously produced
21
Q
What is the formula for calculating clearance?
A
Clearance = (U x V)/P
22
Q
In the clearance formula, what does U represent?
A
Concentration of the substance in urine (mmol/L)
23
Q
In the clearance formula, what does V represent?
A
Volume of urine produced per minute (24hrs urine volume/1440)
24
Q
In the clearance formula, what does P represent?
A
Concentration of the substance in plasma (umol/L)
25
What is considered the gold standard for measuring GFR?
Inulin
26
Why is inulin not practical for routine use in measuring GFR?
It is exogenous
27
What substance is commonly used to estimate GFR instead of inulin?
Creatinine
28
What are the criteria for measuring GFR using creatinine?
* Freely filtered by the glomerulus
* Minimally reabsorbed by the tubules
* Small amount secreted by the tubules (10%)
* Not metabolised by the kidney
* Produced constantly by the body
* Endogenously produced
## Footnote
Creatinine is a byproduct of muscle metabolism, making it a reliable marker for kidney function assessment.
29
What is the Jaffe reaction in measuring creatinine?
* Creatinine reacts with picric acid in an alkaline solution
* Forms a red-orange complex
* Intensity of the color is proportional to creatinine concentration
* Measured at 510-520nm
## Footnote
Non-creatinine chromogens can interfere with the Jaffe reaction, affecting accuracy.
30
What is the enzymatic method for measuring creatinine?
* Creatinine reacts with creatinine amidohydrolase to form creatine
* Creatine reacts with creatine kinase to form ADP
* ADP reacts with PEP to form ATP and pyruvate
* Pyruvate reacts with NADH to form lactate and NAD
* Decrease in NADH measured at 340nm is proportional to creatinine concentration
## Footnote
This method is more specific for creatinine compared to the Jaffe reaction.
31
What is the formula for estimated GFR (eGFR)?
eGFR = estimate of the GFR based on serum creatinine concentration
## Footnote
eGFR is important for assessing kidney function and staging chronic kidney disease.
32
What variables does the Cockcroft-Gault equation use to estimate creatinine clearance?
* Serum creatinine
* Age
* Weight
## Footnote
The Cockcroft-Gault equation provides a rough estimate of kidney function.
33
What variables does the Modification of Diet in Renal Disease (MDRD) equation use to estimate eGFR?
* Serum creatinine
* Age
* Gender
* Ethnicity
## Footnote
The MDRD equation is widely used in clinical practice for evaluating kidney function.
34
What variables does the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation use to estimate eGFR?
* Serum creatinine
* Age
## Footnote
The CKD-EPI equation is considered more accurate than the MDRD equation for estimating eGFR.
35
True or False: Elevated serum creatinine is associated with increased GFR.
False
## Footnote
Elevated serum creatinine levels typically indicate decreased GFR, reflecting impaired kidney function.
36
Fill in the blank: The Jaffe reaction measures creatinine concentration by forming a _______ complex.
red-orange
## Footnote
The color intensity of the complex is indicative of the creatinine concentration in the sample.
37
Why is creatinine not an ideal marker for GFR?
Influenced by muscle mass, diet, and age
## Footnote
Creatinine levels can vary significantly based on individual factors, making them unreliable in certain populations.
38
How does creatinine influence GFR in children?
Influenced by growth; different equations needed
## Footnote
Children have different physiological characteristics that affect creatinine production.
39
What factors influence creatinine in elderly patients?
Influenced by muscle mass; different equations needed
## Footnote
Muscle mass decreases with age, affecting creatinine levels.
40
How does dialysis affect creatinine levels?
Renal function changes rapidly
## Footnote
Dialysis patients may experience fluctuating creatinine levels due to treatment.
41
What is the effect of acute kidney injury on creatinine levels?
Creatinine changes rapidly
## Footnote
Acute kidney injury can cause swift alterations in kidney function, reflected in creatinine levels.
42
How does severe liver disease affect creatinine production?
Creatinine is not produced at a normal rate
## Footnote
Liver dysfunction can lead to decreased creatinine synthesis.
43
What impact does pregnancy have on creatinine levels?
Creatinine is influenced by increased GFR
## Footnote
During pregnancy, the body’s filtration capacity increases, affecting creatinine levels.
44
How can drugs affect creatinine levels?
Excretion of creatinine can be affected by drugs
## Footnote
Certain medications may alter renal function or tubular secretion, impacting creatinine measurements.
45
What is the process of urea measurement?
Urea is hydrolysed by urease to form ammonia and carbon dioxide
## Footnote
This enzymatic reaction is a standard method for quantifying urea in clinical settings.
46
What happens to ammonia during urea measurement?
Reacts with sodium hypochlorite and phenol to form indophenol
## Footnote
The formation of indophenol is a key step in colorimetric assays for urea.
47
What does the intensity of the blue color indicate in urea measurement?
Proportional to the concentration of urea
## Footnote
A higher intensity indicates a greater concentration of urea in the sample.
48
At what wavelength is absorbance measured for urea?
630 nm
## Footnote
This specific wavelength is optimal for detecting the blue color of indophenol.
49
What does glycosuria refer to?
Presence of glucose in the urine
## Footnote
Glycosuria can indicate various medical conditions, most commonly diabetes.
50
What are common benign causes of glycosuria?
Pregnancy, stress, exercise
## Footnote
These conditions can lead to temporary increases in blood glucose levels, resulting in glycosuria.
51
What are pathological causes of glycosuria?
Diabetes, renal tubular defects when plasma glucose is normal
## Footnote
Pathological glycosuria occurs when glucose is excreted despite normal blood glucose levels.
52
What does proteinuria indicate?
Presence of protein in the urine
## Footnote
Proteinuria can be a sign of kidney damage or disease.
53
What is the normal excretion level of protein in urine?
Less than 150 mg/day
## Footnote
Exceeding this level may indicate kidney issues.
54
Why are urine dipstick tests used?
Common in patient screening and monitoring CKD
## Footnote
These tests provide a quick assessment of protein levels in urine.
55
What does proteinuria in pregnancy indicate?
Can be a sign of pre-eclampsia
## Footnote
Pre-eclampsia is a serious condition requiring close monitoring.
56
What is the gold standard for measuring proteinuria?
24-hour urine collection
## Footnote
This method ensures accurate measurement of total protein excretion over a full day.
57
What is the urine protein/creatinine ratio used for?
A more convenient method for measuring proteinuria
## Footnote
This ratio allows for quicker assessments compared to 24-hour collections.
58
In what situations is the urine protein/creatinine ratio particularly useful?
When results are needed quickly, e.g., acute kidney injury, nephrotic syndrome
## Footnote
Rapid assessment is crucial in these conditions for timely medical intervention.
59
What are some diseases that can affect the kidney?
Many diseases can affect the kidney
## Footnote
Some diseases affect several functions, while others selectively affect only one function.
60
What are the initial presentations of renal diseases?
* Dysuria
* Polyuria
* Nocturia
* Renal pain
* Ureteric colic
## Footnote
Ureteric colic is severe pain caused by a kidney stone.
61
What characterizes Chronic Kidney Disease (CKD)?
Progressive loss of kidney function over time, usually irreversible
## Footnote
CKD can lead to end-stage renal disease (ESRD) and can be asymptomatic in early stages.
62
How long must kidney function be lost to diagnose CKD?
At least over 3 months.
63
What is the relationship between CKD and cardiovascular disease?
CKD (even mild) is associated with increased risk of cardiovascular disease.
64
What does eGFR stand for, and what is its significance in CKD?
eGFR stands for estimated Glomerular Filtration Rate, used to stage CKD.
65
What is the eGFR range that indicates normal kidney function?
An eGFR >60 mL/min/1.73 m2 is normal in the absence of other markers of kidney damage.
66
What eGFR levels indicate severely decreased kidney function?
An eGFR of 15-29 indicates severely decreased kidney function.
67
What eGFR level indicates kidney failure?
An eGFR of <15 indicates kidney failure.
68
How is CKD classified?
* Causes
* GFR
* Albuminaemia
69
What are some treatment options for CKD?
* Dietary changes
* Diabetes and blood sugar control
* Dialysis
* Kidney transplantation
* Fluid control
* Medications
70
What are tubular diseases?
Specific disorders of tubular function, which can be selective or non-selective.
71
What is Renal Tubular Acidosis (RTA)?
Involves defect in renal tubular acidification.
72
What is the typical urine pH for RTA?
Urine pH usually 5.5-6.5.
73
What can cause Renal Tubular Acidosis?
* Genetic defects
* Autoimmune diseases
* Drugs
74
What can Renal Tubular Acidosis lead to?
Can lead to metabolic acidosis.
75
What characterizes Type 1 RTA?
Distal tubule defect (inability to excrete H+) – urine pH > 5.5 + watch for kidney stones.
76
What characterizes Type 2 RTA?
Proximal tubule defect (inability to reabsorb HCO−3) – urine pH <5.5.
