Renal

Functions of the Renal System

  • The renal system plays several crucial roles in maintaining homeostasis in the body.

    • Amount of Blood Filtered Per Hour

    • The kidneys filter approximately 120 mL of blood per minute, which translates to about 7,200 mL or 7.2 L per hour.

    • Amount Reabsorbed

    • Out of the filtered blood, around 99% of water and many solutes are reabsorbed.

    • Role in Activation of Vitamin D

    • The kidneys convert 25-hydroxyvitamin D into the active form, calcitriol (1,25-dihydroxyvitamin D), which is essential for calcium absorption in the intestines.

    • Role in Detoxifying Wastes

    • The renal system is responsible for the excretion of metabolic wastes, toxins, and excess substances (e.g., urea, creatinine) from the bloodstream.

    • Role in Fluid Balance

    • The kidneys help maintain fluid balance by adjusting the volume of urine produced based on hydration levels and fluid intake.

    • Role in Electrolyte and Acid-Base Balance

    • The renal system regulates electrolyte levels (sodium, potassium, calcium) and maintains acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate.

    • Role in Production of Erythropoietin

    • The kidneys secrete erythropoietin, a hormone that stimulates red blood cell production in the bone marrow in response to low oxygen levels.

Nephron

  • The nephron is the functional unit of the kidney.

    • Description of the Nephron

    • Each kidney contains approximately one million nephrons, which consist of a renal corpuscle and a renal tubule.

    • What is Creatinine?

    • Creatinine is a waste product formed from muscle metabolism, specifically from the breakdown of creatine phosphate.

    • Normal Values

    • The normal serum creatinine level ranges from 0.5 to 1.5 mg/dL for adults.

    • Hormones Regulating the Kidneys

    • Hormones include antidiuretic hormone (ADH), aldosterone, and atrial natriuretic peptide (ANP) among others.

    • Function of the Collecting Tubule

    • The collecting tubule plays a significant role in water reabsorption and the regulation of potassium and hydrogen ion excretion.

    • Description of Normal Urine

    • Normal urine is typically clear, pale yellow, and mild in odor and primarily consists of water (95%) with urea, creatinine, and electrolytes.

    • Function of the Distal Convoluted Tubule

    • The distal convoluted tubule is involved in the reabsorption of sodium, chloride, and bicarbonate, as well as the secretion of potassium and hydrogen ions.

    • What is BUN (Blood Urea Nitrogen)?

    • BUN is a measure of the amount of nitrogen in the blood that comes from urea, a substance produced during protein metabolism.

    • Normal Values

    • Normal BUN levels range from 5 to 20 mg/dL in adults.

    • Function of the Glomerulus

    • The glomerulus is responsible for filtering blood and forming filtrate by allowing water, ions, and small molecules to pass while retaining larger molecules like proteins.

    • Maintaining Glomerular Filtration

    • Adequate blood pressure and a healthy glomerular structure are vital for maintaining glomerular filtration.

    • What is GFR (Glomerular Filtration Rate)?

    • GFR is a measure of how well the kidneys filter blood.

    • Normal Value

    • A normal GFR ranges from 90 to 120 mL/min/1.73 m².

    • Estimation/Measurement

    • GFR can be estimated using BV or Hydrostatic Pressure

    • Function of the Proximal Convoluted Tubule

    • The proximal convoluted tubule reabsorbs about 60 % of the filtered sodium and water, as well as nearly all glucose and amino acids.

    • Function of the Loop of Henle

    • The Loop of Henle is involved in generating a concentration gradient to the ascending loop, allowing for more effective water reabsorption.

Acute Glomerulonephritis

  • Acute glomerulonephritis is an inflammation of the glomeruli, affecting their filtering ability.

    • Glomerular Damage May Result In:

    • Hematuria, proteinuria, reduced GFR, and edema.

    • Classification of Glomerulopathies

    • Classified based on the cause: primary (affecting only the kidneys) or secondary (resulting from systemic diseases).

    • Labs/Tests

    • Tests include urinalysis, serum creatinine, and immunological tests.

    • Clinical Manifestations

    • Edema due to fluid retention; hematuria causes dark urine; hypertension due to increased fluid volume.

    • Diagnosis

    • Based on clinical presentation, laboratory findings, and kidney biopsy in some cases.

    • Treatment

    • Involves managing symptoms and underlying causes; corticosteroids or other immunosuppressants may be used.

    • Etiology

    • Commonly follows infections, such as streptococcal infections.

    • Pathogenesis

    • Immune response leading to inflammation and damage of glomeruli.

Nephrotic Syndrome

  • Nephrotic syndrome is characterized by significant proteinuria, hypoalbuminemia, edema, and hyperlipidemia.

    • Labs/Tests

    • Tests would show low serum albumin, high 24-hour protein excretion, and lipid levels.

    • Clinical Manifestations

    • Causes generalized edema due to loss of oncotic pressure; foamy urine due to proteinuria.

    • Treatment

    • Involves corticosteroids and dietary modifications.

    • Etiology

    • Can be primary (minimal change disease) or secondary (diabetes).

    • Pathogenesis

    • Podocyte injury leads to increased permeability of glomerular filtration barrier.

Diagnosis of Renal Diseases

  • Diagnosis details should include specific criteria to identify the condition based on labs and clinical presentations.

    • Pathophysiology

    • Understanding how a disease disrupts normal kidney function.

    • Etiology

    • Identifying the underlying causes.

    • Labs/Tests

    • Specific blood and urine tests relevant to the condition.

    • Signs/Symptoms

    • Detailed mechanisms for each symptom occurrence are crucial.

    • High-Risk Groups and Risk Factors

    • Identifying demographics at higher risk for specific renal diseases.

    • Prognosis

    • Understand the likely course and outcome of the disease.

Obstruction

  • Urinary tract obstruction can lead to severe complications.

    • Why is Obstruction a Problem?

    • It can cause hydronephrosis and renal damage due to back pressure.

    • Treatment

    • Depending on the cause, management may involve catheterization, stenting, or surgical intervention.

    • Etiology

    • Causes include kidney stones, tumors, or structural anomalies.

    • Pathogenesis

    • Involves blockage that leads to increased pressure within the urinary tract.

    • Clinical Manifestations

    • Symptoms may include flank pain, hematuria, and signs of urinary tract infections.

Pyelonephritis

  • Pyelonephritis is a kidney infection that can be acute or chronic.

    • Acute vs Chronic

    • Chronic pyelonephritis can result in scarring and chronic renal failure, while acute may resolve with treatment.

    • Treatment (Acute)

    • Typically antibiotics and managing symptoms; hospitalization may be needed in severe cases.

    • Clinical Manifestations (Acute)/chronic

    • Fever, chills, flank pain, and dysuria. Sudden episode of htn

    • Etiology (Acute)

    • Often caused by bacterial infections such as E. coli.

    • Pathogenesis (Acute)

    • Infection leads to renal inflammation and potential abscess formation.

Clinical Manifestations of Renal Conditions

  • Various signs and symptoms may arise from kidney conditions.

    • CVA Tenderness

    • Costovertebral angle tenderness can indicate kidney pathology, often occurring in infections.

    • Pain

    • Pressure from inflamed tissues or kidney stones (renal colic).

    • Hematuria

    • Caused by stones or ruptured vessels in kidneys; noted in several renal diseases.

    • Hypervolemia and Hypertension

    • Stimulated by activation of the renin-angiotensin-aldosterone system (RAAS) due to impaired kidney function.

Autosomal Recessive Polycystic Kidney Disease

  • A genetic condition resulting in kidney growth and fluid-filled cysts from birth.

    • Etiology/Pathogenesis

    • Caused by genetic mutations leading to cyst formation in kidneys.

    • Symptoms

    • Often include hypertension, recurrent urinary tract infections, and progressive kidney function loss.

    • Diagnosis

    • Diagnosed via ultrasound and genetic testing; may reveal enlarged kidneys and cysts.

Autosomal Dominant Polycystic Kidney Disease

  • Symptoms usually manifest later in life.

    • Etiology/Pathogenesis

    • Features hyperplasia of renal epithelial cells leading to the development of numerous cysts.

    • Consequences

    • Can lead to hypertension and renal failure due to progressive kidney damage.

    • Treatment

    • Focuses on managing hypertension and preventing complications.

Renal Cell Carcinoma

  • Characterized by the uncontrolled proliferation of renal cells.

    • Risk Factors

    • Include smoking, obesity, and hypertension.

    • Staging

    • Determined by the tumor size and spread; TNM classification is often applied.

    • Clinical Manifestations

    • Symptoms may include hematuria, flank pain, and weight loss.

    • Etiology

    • Mostly unknown, but some genetic conditions increase risk.

Acute Kidney Injury

  • Acute kidney injury (AKI) is characterized by a rapid decline in renal function.

    • Is it Reversible?

    • Yes, particularly with timely intervention.

    • Three Broad Categories

    • Pre-Renal: Decreased blood flow to the kidneys.

    • Post-Renal: Obstruction of urine flow.

    • Intra-Renal: Damage to kidney tissue itself.

    • What is Oliguria?

    • Oliguria is defined as producing less than 400 mL of urine per day.

    • What is Anuria?

    • Anuria is the absence of urine output, less than 100 mL per day.

    • Risk Factors

    • Include dehydration, heart failure, and certain medications.

Pathogenesis of Acute Kidney Injury

  • Pre-Renal

    • Decreased renal perfusion leads to azotemia.

    • Etiology: Dehydration, heart failure, shock, heavy diuresis, burns, etc.

    • Treatment: Hydration and restoring blood flow.

  • Post-Renal

    • Occurs due to obstructions affecting urine outflow.

    • Etiology: Benign prostatic hyperplasia, tumors, strictures, calculi.

    • Treatment: Relieving the obstruction and managing underlying causes.

  • Intra-Renal

    • Results from direct damage to renal parenchyma, leading to acute tubular necrosis (ATN).

    • Treatment may include monitoring and supportive care, with potential dialysis for severe cases.

Hemodialysis

  • Hemodialysis utilizes a machine to filter waste products, toxins, and excess fluids from the blood when kidneys fail.

  • Peritoneal Dialysis

    • A home treatment option that uses the abdominal lining (peritoneum) as a filter for waste and excess fluid removal.

  • Labs/Tests

    • Regular monitoring of electrolytes, BUN, and creatinine for efficacy of dialysis treatments.

Chronic Kidney Disease

  • Chronic Kidney Disease (CKD) is a long-term condition characterized by gradual loss of kidney function.

    • Stages of CKD

    • 1) Kidney damage with normal or increased GFR.

    • 2) Mild reduction in GFR (60-89 mL/min).

    • 3) Moderate reduction in GFR (30-59 mL/min).

    • 4) Severe reduction in GFR (15-29 mL/min).

    • 5) Kidney failure (GFR < 15 mL/min).

    • Complications

    • Include cardiovascular disease, skin changes, infections, and encephalopathy.

    • Etiology/Pathogenesis

    • Conditions such as diabetes and hypertension lead to nephron damage, promoting fibrosis and eventual organ failure.

Micturition

  • Micturition is the act of urination.

    • What is Incontinence?

    • Incontinence refers to the involuntary leakage of urine.

    • Pathogenesis of Incontinence

    • Often involves dysfunction within the urinary tract or nervous system.

    • Types of Incontinence

    • Functional Incontinence: Difficulty reaching the toilet due to physical or cognitive limitations.

    • Overflow Incontinence: Occurs when the bladder is over-distended.

    • Mixed Incontinence: A combination of urge and stress incontinence.

    • Urge Incontinence: Sudden, intense urge to urinate leading to involuntary loss of urine.

    • Stress Incontinence: Leakage of urine during physical activities that increase abdominal pressure.

    • Definition of Continent: The ability to control urination.

    • Definition of Micturition: The process of expelling urine from the bladder into the urethra.

    • Normal Bladder Capacity: Approximately 400-600 mL is the normal bladder capacity.

    • Urge to Void: The urge typically occurs when the bladder reaches about 150-200 mL.

    • Post Void Residual: The amount of urine remaining in the bladder after voiding.

Cystitis

  • Cystitis is the inflammation of the bladder, commonly due to infection.

    • Definition of CAUTI (Catheter-Associated Urinary Tract Infection)

    • An infection that occurs in the urinary tract due to catheterization.

    • Prevention Strategies

    • Include proper catheter care, minimizing catheter use, and maintaining hygiene.

    • Labs/Tests

    • Urinalysis, urine culture, and sensitivity testing are common practices.

    • Clinical Manifestations:

    • Symptoms may include dysuria, urgency, frequency, and suprapubic pain due to bladder inflammation.

    • Treatment:

    • Antibiotics are prescribed to treat infections, and analgesics may help alleviate pain.

    • Etiology/Pathogenesis

    • Most often caused by bacterial infections, primarily E. coli.

Kidney Infection in General

  • Kidney infections can arise from various risk factors.

    • Risk Factors for Kidney Infections

    • Include urinary tract obstruction, pre-existing urinary tract infections, female anatomy, and recent catheterization.

    • Protective Mechanisms

    • The body utilizes multiple barriers, such as the flushing action of urine, local immune responses, and the presence of antibacterial properties in urine.

Incontinence Types

  • Functional Incontinence

    • Occurs when physiological or cognitive conditions prevent reaching the restroom in time.

    • Overflow Incontinence

    • Results when the bladder is not fully emptying, leading to frequent leakage.

    • Mixed Incontinence

    • When symptoms of both urge and stress classifications are present.

    • Urge Incontinence

    • Characterized by a sudden, uncontrollable urge to urinate.

    • Stress Incontinence

    • Loss of urine during activities that put pressure on the bladder, such as sneezing or exercising.