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Questions and Answers
What is the most common form of kidney disease?
What is the most common form of kidney disease?
CKD can only be diagnosed using imaging techniques.
CKD can only be diagnosed using imaging techniques.
False
What is the principal feature used to diagnose Chronic Kidney Disease?
What is the principal feature used to diagnose Chronic Kidney Disease?
eGFR (glomerular filtration rate)
A value above _____ mL/min/1.73m2 is considered normal for eGFR.
A value above _____ mL/min/1.73m2 is considered normal for eGFR.
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Match the definitions to the correct terms related to kidney disease:
Match the definitions to the correct terms related to kidney disease:
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Which organization develops clinical practice guidelines for kidney disease?
Which organization develops clinical practice guidelines for kidney disease?
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Symptoms of CKD are usually easily noticeable by the patient.
Symptoms of CKD are usually easily noticeable by the patient.
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The presence of proteins from cell linings in the urine is a result of _____ proteinuria.
The presence of proteins from cell linings in the urine is a result of _____ proteinuria.
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What indicates a healthy kidney in terms of urine osmolality compared to plasma osmolality?
What indicates a healthy kidney in terms of urine osmolality compared to plasma osmolality?
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A rise in urine osmolality during the water deprivation test suggests a disruption in vasopressin secretion.
A rise in urine osmolality during the water deprivation test suggests a disruption in vasopressin secretion.
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What is the primary indication of abnormal glomerular function as observed in urinalysis?
What is the primary indication of abnormal glomerular function as observed in urinalysis?
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The test that can indicate tubule dysfunction by assessing urine osmolality is called the __________.
The test that can indicate tubule dysfunction by assessing urine osmolality is called the __________.
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Match the following forms of proteinuria with their descriptions:
Match the following forms of proteinuria with their descriptions:
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During the water deprivation test, at what point should the test be stopped?
During the water deprivation test, at what point should the test be stopped?
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Point-of-care tests for urinalysis are performed in a laboratory.
Point-of-care tests for urinalysis are performed in a laboratory.
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What is the main protein in blood that is often assessed in cases of proteinuria?
What is the main protein in blood that is often assessed in cases of proteinuria?
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What is the primary function of the kidneys?
What is the primary function of the kidneys?
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Each kidney contains approximately 1 million nephrons.
Each kidney contains approximately 1 million nephrons.
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What is the glomerular filtration rate (GFR) in a healthy adult?
What is the glomerular filtration rate (GFR) in a healthy adult?
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The process of transferring waste from blood capillaries into Bowman's capsule is called ______.
The process of transferring waste from blood capillaries into Bowman's capsule is called ______.
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Match the kidney functions with their descriptions:
Match the kidney functions with their descriptions:
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What occurs in the proximal convoluted tubule?
What occurs in the proximal convoluted tubule?
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Bowman's capsule contains thick cellular layers that allow blood cells to pass through.
Bowman's capsule contains thick cellular layers that allow blood cells to pass through.
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What role does the Loop of Henle play in kidney function?
What role does the Loop of Henle play in kidney function?
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What causes water to move out of the loop of Henle and into the interstitial fluid (ISF)?
What causes water to move out of the loop of Henle and into the interstitial fluid (ISF)?
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The ascending loop of Henle is permeable to sodium.
The ascending loop of Henle is permeable to sodium.
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What is the primary purpose of measuring creatinine clearance?
What is the primary purpose of measuring creatinine clearance?
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Water reabsorption in the collecting ducts is aided by __________.
Water reabsorption in the collecting ducts is aided by __________.
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What major factor affects serum creatinine levels?
What major factor affects serum creatinine levels?
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Match the following components with their respective roles in kidney function:
Match the following components with their respective roles in kidney function:
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The GFR measurement through creatinine clearance is practical for patients to collect over 24 hours.
The GFR measurement through creatinine clearance is practical for patients to collect over 24 hours.
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What must be measured to better estimate GFR in clinical populations?
What must be measured to better estimate GFR in clinical populations?
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Study Notes
Kidney Function and Disease
- Kidneys perform waste excretion, fluid balance maintenance, hormone synthesis, and glucose production.
- Blood is delivered to the kidneys via the renal artery and returns via the renal vein.
- Specialized functional units within kidneys are called nephrons.
The Nephron
- Each nephron consists of a cluster of capillaries (glomerulus) and a tubule.
- Blood passes through alongside the glomerulus for filtration and functioning.
- Two key functions are glomerular function and tubular function.
- A fully functional kidney contains one million nephrons.
Ultrafiltration
- The initial process of removing metabolic waste from the blood.
- Occurs in the glomerulus, transferring waste from capillaries to Bowman's capsule.
- Non-specific filtration happens under high pressure, forcing blood into the capsule.
- Pressure is generated by the wide entrance and narrow exit of the glomerulus.
- The glomerulus's tuft of capillaries has a large surface area (renal surface area).
Bowman's Capsule
- The inner surface of the cells in Bowman's capsule is made of podocytes.
- Podocytes are surrounded by blood capillaries and have pores that allow blood components to enter the capsule.
- A cellular layer called the basement membrane separates the capillaries and podocytes.
- This membrane allows smaller components to pass but blocks larger ones, such as blood cells.
- Ultrafiltrate is produced, similar to plasma but without plasma proteins.
Glomerular Filtration
- The rate at which plasma is filtered in the glomeruli is glomerular filtration rate or GFR.
- In a healthy adult, GFR is approximately 120-140 mL/min (170-20L/day).
- Urine production is approximately 1-2L/day and most of the filtrate is reabsorbed.
- Filtration, passive and active mechanisms, occur along the tubules.
- A large amount of the filtered material is absorbed back into the blood.
Tubular Function
- It occurs in the proximal convoluted tubule.
- Water passively moves across barriers back into the blood.
- 75% of sodium, glucose, amino acids, vitamins, hormones, potassium, and bicarbonate are reabsorbed back into the blood.
Water Balance - Loop of Henle
- Water is reabsorbed in the collecting ducts and is assisted by vasopressin.
- A salt gradient is created in the loop of Henle, to facilitate water reabsorption.
- The descending limb of the loop of Henle is permeable to water, which allows water to leave the filtrate, increasing its concentration.
- The ascending limb of the loop of Henle is impermeable to water but is permeable to sodium, which gets actively pumped into the interstitium, maintaining the osmotic gradient.
Measurement of Kidney Function
- Kidney disorders affect glomerular or tubular functions.
- Kidney functionality is tested using clearance tests.
- Clearance testing measures how quickly a substance is removed from the blood through the kidneys.
- Creatinine clearance is a commonly used test to estimate glomerular filtration rate (GFR).
Calculating Estimate GFR (eGFR)
- GFR estimations account for age, sex, ethnicity, and body mass.
- Serum creatinine measurement is a parameter used in GFR estimation.
Investigating Kidney Function
- Determining the cause of impaired kidney function.
- Useful to determine how effective treatment is.
- Urine osmolality is a general indicator of renal tubule function.
Water Deprivation Test
- A single urine osmolality test may be inconclusive regarding tubule function.
- Urine osmolality measurement is part of the investigation process.
- This test determines if a patient is properly retaining or losing water.
Urine Strip
- Urine strips can be dipped directly into urine to test for abnormalities.
- Abnormalities can be detected using colour changes on the test strip.
- Excessive protein in the urine can indicate a problem.
- The tests are useful to aid in diagnosis of issues related to kidney function.
Forms of Proteinuria
- Glomerular
- Protein damage in the basement layer.
- Excess protein excretion.
- Often a sign of nephritic disorder.
- Overflow
- Too much protein in the blood (overflow).
- Tubular
- Proteins leaking from the damaged kidney tubules.
Kidney Disease
- A broad term covering a range of kidney disorders.
- Most common form is CKD (chronic kidney disease).
- CKD is often caused by other conditions such as diabetes, high blood pressure, or infections.
Chronic Kidney Disease (CKD)
- Abnormalities in kidney structure or function for over 3 months.
- eGFR of less than 60 mL/min/1.73m² is a sign of impaired function.
- CKD stages are categorized based on GFR and albuminuria levels.
Risk Factors for CKD
- Genetic predisposition
- Family history of kidney disease
- Age and sex differences
- Obesity
- Socioeconomic status
- Smoking
- Diabetes
- Hypertension
- CVD (cardiovascular disease)
Metabolic Consequences of CKD
- Mild to moderate CKD can be carefully managed.
- As CKD progresses, metabolic side effects exacerbate the condition.
Water Balance
- Patients with CKD have a reduced capacity to reabsorb water.
- This can lead to increased urine production (polyuria), particularly in later stages.
Electrolyte Disorders
- Common feature of advanced CKD is hyperkalemia.
- Reduction of K+ secretion capacity and impaired urine buffering capacity contribute to K+ increase.
Clinical Signs of Kidney Failure
- Manifestations such as nausea, vomiting, headaches, appetite loss, fatigue, lower limb edema, chest pain, shortness of breath, and sleep disruption frequently accompany CKD.
AKI (Acute Kidney Injury)
- Rapid decline in kidney function.
- Causes include reduced renal perfusion, intrinsic kidney damage, and post-renal obstruction.
- AKI is staged based on creatinine concentration and urine output.
AKI Management
- Addressing the underlying cause of AKI is crucial.
- Preventing fluid overload, and ensuring adequate electrolyte and hydration balance are key strategies.
- If necessary, prompt referral to appropriate specialists is recommended.
Renal Replacement Therapy
- Dialysis (haemodialysis or peritoneal) is used for patients with severe kidney failure.
- Dialysis removes waste products from the blood since the kidney is unable to function efficiently.
- Dialysis is a life-sustaining treatment for patients with kidney failure.
Haemofiltration
- Uses an extracorporeal circuit (like haemodialysis).
- Does not use dialysate; primarily convective removal of waste products.
- Can also filter urea and mid-sized molecules.
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Description
Explore the functions of the kidneys and the role of nephrons in waste excretion and fluid balance. Understand the processes involved in ultrafiltration and how blood is filtered in the glomerulus. Test your knowledge about the intricate workings of the renal system.
