38 Questions
What is the primary function of the kidneys in the body?
Major excretory organ for elimination of metabolic wastes from the body and regulating the amount of water, solutes, and electrolytes in the blood.
What are the kidneys protected by?
Muscle, fat, and ribs.
What is the function of erythropoietin produced by the kidneys?
Stimulates the production of red blood cells.
What is the function of the glomerulus in the nephron?
Filters your blood.
How much blood do the kidneys filter every minute?
About a half cup of blood every minute.
What is the function of the tubule in the nephron?
Returns needed substances to your blood and removes wastes.
Why would a doctor order a Renal Function Test (RFT)?
A doctor would order an RFT if they suspect a person's kidneys may not be working properly, or if the person has other conditions that can harm the kidneys, such as diabetes or high blood pressure.
What is the normal color of urine in a healthy individual?
The normal color of urine in a healthy individual is pale yellow.
What are the three main components of Urine Analysis in Renal Function Tests?
The three main components are Physical, Chemical, and Microscopic.
What is the purpose of the Blood Urea Nitrogen (BUN) test in Renal Function Tests?
The purpose of the BUN test is to aid in evaluating kidney function.
What does a low specific gravity in urine analysis indicate?
A low specific gravity in urine analysis indicates tubular damage or the absence of ADH.
What is the normal volume of urine produced per day in a healthy individual?
The normal volume of urine produced per day in a healthy individual is 1.2-2L/day, with an average of 1.5L.
What does the presence of pus cells in urine analysis indicate?
The presence of pus cells in urine analysis indicates infection or inflammation in the kidneys or urinary tract.
What is the normal pH range of urine in a healthy individual?
The normal pH range of urine in a healthy individual is 6-6.5.
What is the normal range of serum urea in mg/dl?
15-45 mg/dl
What is the normal range of serum creatinine in mg/dl?
0.6 – 1.2 mg/dl
What is the formula to calculate creatinine clearance?
Ccr = Ucr.V / Pcr
What is the normal range of glomerular filtration rate (GFR) in mL per minute for an adult male?
90 to 120 mL per minute
What is the purpose of the dilution test in renal function tests?
To assess the kidney's ability to dilute urine
What is the significance of a low fixed specific gravity in urine?
It is indicative of chronic kidney disease
What is the purpose of the urine concentration test in renal function tests?
To assess the kidney's ability to concentrate urine
What is the definition of kidney (renal) failure?
When kidneys don't work as well as they should, to the point where kidney replacement is required
What is the term used to describe a range of problems that can result in kidney failure?
Kidney failure
What are the three main categories of causes of Acute Renal Failure (ARF)?
Prerenal, Renal (intrinsic), and Postrenal
What is the primary characteristic of Acute Renal Failure (ARF)?
A sudden and almost complete loss of kidney function over a period of hours to days
What is the most common cause of Acute Renal Failure (ARF), accounting for 60%-70% of cases?
Prerenal causes, resulting from impaired blood flow to the kidney
What is the phase of Acute Renal Failure (ARF) characterized by a decrease in urine output?
Oliguria
What is the final phase of Acute Renal Failure (ARF), characterized by the recovery of kidney function?
Recovery
What is the consequence of postrenal causes of Acute Renal Failure (ARF)?
Obstruction distal to the kidneys, leading to increased pressure in the kidney tubules and decreased GFR
How long does the initiation phase of Acute Renal Failure (ARF) typically last?
Few hours to 2 days
What are the common signs and symptoms of Acute Renal Failure?
Swelling of the hands, feet, and face (edema), internal bleeding, confusion, seizures, coma, and abnormal blood and urine tests.
What is the primary treatment goal for dehydration in Acute Renal Failure?
Fluids
What are the two types of diabetes that are major risk factors for Chronic Renal Failure?
Diabetes mellitus type 1 and type 2
What is the classification of Chronic Kidney Disease based on the level of kidney function?
Stages 1-5, based on the level of GFR (Glomerular Filtration Rate)
What are the non-modifiable risk factors for Chronic Kidney Disease?
Older age, male gender, and non-Caucasian ethnicity
What is the significance of oliguria in the maintenance phase of Acute Renal Failure?
Urine output less than 400 mL/day
What is the common cause of fluid overload in the maintenance phase of Acute Renal Failure?
Oliguria and anuria
What is the purpose of dialysis in the treatment of Acute Renal Failure?
To remove waste products from the blood when they reach a dangerously high level
Study Notes
Kidney Function and Structure
- Kidneys are paired retroperitoneal organs located at the level of T12 to L3 vertebral bodies, protected by muscle, fat, and ribs.
- Healthy kidneys filter about half a cup of blood every minute, removing wastes and extra water to make urine.
- The kidneys regulate the amount of water, solutes, and electrolytes in the blood.
Primary and Secondary Functions
- Primary function: major excretory organ for eliminating metabolic wastes from the body.
- Secondary functions:
- Acid-base balance
- Producing erythropoietin, which stimulates the production of red blood cells
- Producing renin for blood pressure regulation
- Converting vitamin D to its active form, which helps in calcium absorption
Nephrons and How They Work
- Kidneys are made up of about a million filtering units called nephrons.
- Each nephron includes a filter, called the glomerulus, and a tubule.
- The nephrons work through a two-step process:
- Glomerulus filters the blood (180 L/day).
- Tubule returns needed substances to the blood and removes wastes.
Renal Function Tests (RFT)
- RFT is ordered if the doctor suspects kidney problems or if the patient has other conditions that can harm the kidneys, such as diabetes or high blood pressure.
- RFT is useful for:
- Identifying the presence of renal disease
- Monitoring the response of kidneys to treatment
- Determining the progression of renal disease
Urine Analysis
- Physical:
- Color: normal - pale yellow, cloudy - pus, bacteria, fungi, or amorphous urates and phosphates, milky or opaque - Nephrotic Syndrome, greenish yellow - Obstructive Jaundice
- Clarity: normal - clear, cloudy - pus, bacteria, fungi, or amorphous urates and phosphates
- Odor: normal - no unusual smell, abnormal - sweet, fruity, or ammonia-like smell
- Volume: normal - 1.2-2 L/day (avg. 1.5 L), oliguria - less than 400 ml, anuria - less than 100 ml, polyuria - greater than 2.5 L/day
- Chemical:
- Glucose: normal - absent, abnormal - present
- Albumin: normal - absent, abnormal - present
- Blood: normal - absent, abnormal - present
- Bile salts and bile pigments: normal - absent, abnormal - present
- Urobilinogen: normal - absent, abnormal - present
- Ketone body: normal - absent, abnormal - present
- Microscopic:
- Pus cells: normal - absent, abnormal - present
- Epithelial cells: normal - absent, abnormal - present
- Crystals: normal - absent, abnormal - present
- Cysts: normal - absent, abnormal - present
Blood Tests
- Blood urea nitrogen (BUN) test
- Creatinine test
- Measurement of blood levels of:
- Sodium
- Potassium
- Chloride
- Bicarbonate
- Calcium
- Magnesium
- Phosphorus
- Protein
- Uric acid
- Glucose
Glomerular Function Tests
- Clearance measurements:
- Clearance of a substance is the volume of plasma (ml) completely freed of a given substance per minute by the kidneys.
- Clearance tests for GFR:
- Inulin clearance
- Creatinine clearance (Ccr = Ucr.V / Pcr)
- Urea clearance
Renal Failure
- Kidney (renal) failure is when kidneys don't work as well as they should, to the point where kidney replacement is required.
- Kidney replacement can be accomplished by different kinds of dialysis or by kidney transplant.
- Causes of renal failure:
- Kidney doesn't get enough blood to filter
- Kidney is hurt by a disease like diabetes, high blood pressure, glomerulonephritis, or polycystic kidney disease
- Kidney is blocked by a kidney stone or scar tissue
Acute Renal Failure (ARF)
- Acute renal failure (ARF) is a relatively sudden decrease in renal function leading to serious derangements of body fluid homeostasis.
- Causes of ARF:
- Prerenal (60-70% of cases): impaired blood flow to the kidney leading to hypoperfusion and decreased GFR
- Intrinsic (renal): parenchymal damage to glomeruli or kidney tubules
- Postrenal: obstruction distal to the kidneys leading to pressure rise in the kidney tubules and decreased GFR
- Phases of ARF:
- Initiation phase: potentially reversible, few hours to 2 days
- Oliguria/anuria phase: BUN and creatinine increase daily, fluid overload, electrolyte imbalances, and acidosis
- Diuresis phase: polyuria and high urine output
- Recovery phase: improvement in renal function and return to normal
Chronic Renal Failure (CRF)
- Chronic kidney disease (CKD) is a gradual loss of kidney function over time.
- Causes of CKD:
- Diabetes mellitus type 2 (30-50%)
- Diabetes mellitus type 1 (3.9%)
- Hypertension (27.2%)
- Primary glomerulonephritis (8.2%)
- Chronic tubulointerstitial nephritis (3.6%)
- Hereditary or cystic diseases (3.1%)
- Secondary glomerulonephritis or vasculitis (2.1%)
- Plasma cell dyscrasias or neoplasm
- Classification of CKD:
- Stage 1: kidney damage with normal or elevated GFR (>90)
- Stage 2: kidney damage with mild reduction in GFR (60-89)
- Stage 3: moderate reduction in GFR (30-59)
- Stage 4: severe reduction in GFR (15-29)
- Stage 5: end-stage renal disease (ESRD) (<15)
Learn about the structure and functions of the kidneys, including their location, filtration process, and regulation of water, solutes, and electrolytes in the blood.
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