Untitled Quiz

Disorders of Renal Function

• Renal system components include kidneys, ureters, bladder, and urethra.
• Kidneys are located retroperitoneally in the lumbar area.
• Kidneys produce and excrete urine to maintain homeostasis, regulate body fluid balance (volume, electrolytes, and acid-base), detoxify blood, eliminate wastes, regulate blood pressure, and support red blood cell production.
• Ureters transport urine to the bladder.
• The bladder serves as a reservoir for urine until excretion via the urethra.
• The nephron is the functional unit of the kidney, consisting of renal corpuscle and renal tubules.
• Bowman's capsule, part of the collecting system, is contained within the renal corpuscle.
• Glomerulus, composed of afferent and efferent arterioles, resides within the renal corpuscle.
• Renal/nephron tubules include proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting tubule.
• Nephron functions involve glomerular filtration, reabsorption, and secretion.

Urine Formation

• Glomerular filtration occurs within the renal corpuscle, where all solutes except macromolecules (like proteins) pass through by passive diffusion.
• Glomerular filtration rate (GFR) is the volume of glomerular filtrate produced per minute (125 ml/min).
• Reabsorption occurs in the proximal and distal convoluted tubules, moving substances from tubular fluid to blood.
• Secretion occurs in the distal convoluted tubules, moving substances from blood to tubular fluid.
• Concentration occurs in collecting tubules.

Factors Affecting Urine Production

• GFR is determined by blood vessel arrangement and modulated by: autoregulation (local feedback from muscle tension in afferent arteriole), sympathetic nervous system and renin.
• Hormones (primarily aldosterone from adrenal cortex, ANH from atrial wall of the heart, and antidiuretic hormone from posterior pituitary) control urine volume via fluid and electrolyte balance.

Urinary Tract Infections (UTIs)

• UTIs are common, affecting millions annually. Urine provides an excellent medium for microbial growth.
• Cystitis and urethritis affect the lower urinary tract, whereas pyelonephritis affects the upper.
• Most infections ascend from the perineal area to the kidneys via the urinary tract.
• Occasionally, pyelonephritis can result from a blood-borne infection. Escherichia coli is a prevalent causative organism.

Pathophysiology of Cystitis

• Inflammation, redness, swelling, and potential ulceration of the bladder and urethra characterize cystitis.
• Bladder wall irritation results in reduced bladder capacity.
• Symptoms can range from mild to unnoticed, including pain in the lower abdomen, dysuria, urgency, frequency, nocturia, and systemic signs of infection (fever, malaise, nausea, leukocytosis).
• Urine often appears cloudy and has a foul odor. Urinalysis can reveal bacteriuria, pyuria, and hematuria.

Incontinence and Retention

• Incontinence is the loss of bladder control, with enuresis defining involuntary urination after age 4-5.
• Most causes of incontinence are related to factors like developmental delays, sleep patterns, and psychosocial aspects, rather than physical defects.
  • Stress incontinence occurs when increased intra-abdominal pressure forces urine through the sphincter. Common in women after multiple pregnancies.
  • Overflow incontinence results from an incompetent bladder sphincter; weakens detrusor muscle leads to urinary retention.
  • Retention, an inability to empty the bladder, can be accompanied by overflow incontinence.

Acute Pyelonephritis

• Acute pyelonephritis is a sudden inflammation of the kidneys, typically caused by bacteria.
• This condition frequently affects the interstitial area and renal pelvis, and less commonly, the renal tubules.
• Often more common in females due to shorter urethra and proximity of urinary meatus to the vagina.
• Bacterial infection of the kidneys, often from normal intestinal/fecal flora, is a contributing cause.
• Escherichia coli is a frequent causative organism.

Chronic Pyelonephritis

• Chronic pyelonephritis is persistent kidney inflammation, potentially leading to scarring and chronic renal failure.

Glomerulonephritis

• Glomerulonephritis is bilateral glomeruli inflammation usually resulting from streptococcal infection..
• Acute glomerulonephritis frequently affects boys aged 3 to 7, but can occur at any age.
• Chronic glomerulonephritis is a slowly progressing inflammatory condition that causes scarring and eventually leads to renal failure.
• The epithelial layer of glomerular membrane is disturbed.
• Changes in permeability of the membrane result from trapped antigen-antibody complexes.
• The inflammatory response negatively impacts GFR, causing fluid retention and reduced urine output. Common symptoms include: decreased urination, smoky/coffee-colored urine from hematuria, and periorbital edema.

Nephrotic Syndrome

• Nephrotic syndrome arises from glomerular permeability defects, typically affecting 75% of those with the condition.
• Common causes include allergic reactions, circulatory issues (e.g., heart failure), sickle cell anemia, collagen-vascular disorders (e.g., systemic lupus erythematosus), hereditary conditions, and infections (e.g., tuberculosis).
• Key characteristics include proteinuria, hypoalbuminemia, hyperlipidemia, and edema.
• The pathophysiology involves damage to the glomerular membrane, resulting in increased permeability for plasmic proteins (albumin and immunoglobulins).

Renal Calculi

• Renal calculi (kidney stones) develop when substances like calcium oxalate and calcium phosphate precipitate, concentrate, and form in the urinary tract (frequently the renal pelvis).
• Causing factors include dehydration, changes in urine pH, dietary factors (e.g., excessive protein, high calcium intake), gout, immobilization, and urinary tract obstructions.
• Symptoms can range from mild to severe flank pain, nausea, vomiting, and fever/chills resulting from infection.

Hydronephrosis

• Hydronephrosis is a secondary complication frequently ensuing from calculi, tumors, scar tissue, or untreated prostatic enlargement.
• Obstruction of urine outflow leads to back pressure and kidney/ureter dilation, ultimately causing necrosis of tissue.
• Diagnosis is often made with ultrasonography, radionuclide imaging, CT scans, or IVP.

Tumors

• Benign urinary tract tumors are rare, while malignant ones often manifest in men after age 50, linked to smoking.
• Several malignant tumor types exist (e.g., Renal Cell Carcinoma, Bladder Cancer) arising from various cellular origins.
• Tumors tend to develop multiple nodules, recur, and metastasize progressively to distant organs.
• Symptoms include painless hematuria, flank pain, palpable masses, and anemia. Treatment typically involves surgical removal of the affected tissues, and/or radiation or chemotherapy.

Renal Failure

• Renal failure is a condition where the kidneys lose their function in removing metabolic wastes and regulating fluid, electrolyte, and pH balance.

• It can develop in several forms—acute or chronic—each with its own specific pathophysiology.

  • Acute Renal Failure (ARF): This is an abrupt onset of kidney failure, often temporary due to hypovolemia, heart failure/shock, prolonged ischemia, nephrotoxic exposure, or acute renal disease.
  • Chronic Renal Failure (CRF): Gradual loss of kidney function usually develops due to factors like hypertension, diabetes, polycystic kidney disease, urinary obstructions, glomerulonephritis, or tumors.

• Three phases (oliguric, diuretic, and recovery) can be observed in acute renal failure.

• Chronic renal failure manifests with early symptoms like oliguria, azotemia (excess nitrogenous waste), electrolyte imbalances, and metabolic acidosis, leading to more severe complications in later stages.