Kidney Function and Diseases: A Comprehensive Guide

**1. Structure of the Kidney** - **Pathophysiology**: The kidneys consist of two main regions: the outer **renal cortex** and the inner **renal medulla**, which house the functional units called **nephrons**. - **Etiology**: In kidney disease, structural damage (e.g., glomerular in...

**1. Structure of the Kidney** - **Pathophysiology**: The kidneys consist of two main regions: the outer **renal cortex** and the inner **renal medulla**, which house the functional units called **nephrons**. - **Etiology**: In kidney disease, structural damage (e.g., glomerular injury, tubulointerstitial fibrosis) can impair the kidney's ability to filter blood, leading to waste accumulation in the body. - **Manifestations**: Symptoms of structural kidney issues may include flank pain, edema, hypertension, and in severe cases, renal failure. **2. Segments of the Nephron Tubules and Primary Functions** - **Proximal Convoluted Tubule (PCT)**: Responsible for reabsorbing most of the filtered water, electrolytes, and glucose. - **Patho**: Damage to the PCT can lead to impaired reabsorption, resulting in electrolyte imbalances and dehydration. - **Loop of Henle**: Creates a concentration gradient that is essential for water reabsorption. - **Patho**: Disruption can lead to problems concentrating urine and imbalanced fluid status. - **Distal Convoluted Tubule (DCT)**: Involved in sodium reabsorption and potassium secretion under the influence of hormones like aldosterone. - **Patho**: Dysfunction can lead to electrolyte disturbances, especially affecting potassium levels. - **Collecting Duct**: Final site for water reabsorption, influenced by ADH. - **Patho**: Damage leads to polyuria or oliguria depending on ADH regulation. **3. Normal Functions of the Kidneys** - **Pathophysiology**: The kidneys filter blood, regulate fluid and electrolyte balance, and excrete waste products like urea and creatinine. They also regulate blood pressure through the renin-angiotensin-aldosterone system (RAAS) and produce erythropoietin for red blood cell production. - **Etiology**: Kidney dysfunction arises from factors like diabetes, hypertension, infections, or autoimmune diseases, leading to fluid retention, electrolyte imbalance, or failure to excrete toxins. - **Manifestations**: Symptoms of impaired kidney function include swelling, high blood pressure, fatigue, and confusion. **4. Characteristics of Normal Urine** - **Pathophysiology**: Normal urine is clear, light yellow in color, and contains minimal protein, glucose, and no blood. - **Etiology**: Deviations from normal urine characteristics can occur due to underlying renal or systemic issues like infections or metabolic disorders. - **Manifestations**: Dark or cloudy urine, hematuria, or foul-smelling urine can indicate infection or kidney pathology. **5. Specific Gravity, BUN, Creatinine, GFR** - **Pathophysiology**: These are indicators of kidney function: - **Specific Gravity**: Measures urine concentration. Normal is between 1.010 and 1.030. Abnormalities may indicate dehydration or renal disease. - **Blood Urea Nitrogen (BUN)**: Reflects kidney filtration; elevated levels indicate kidney dysfunction or dehydration. - **Creatinine**: A byproduct of muscle metabolism, often used as a marker of kidney function; elevated levels indicate renal impairment. - **Glomerular Filtration Rate (GFR)**: A measure of kidney filtering capacity. A decrease in GFR indicates impaired kidney function. - **Etiology & Manifestations**: Changes in these values signal acute or chronic kidney disease, dehydration, or glomerular injury. **6. Kidney Stones** - **Pathophysiology**: Stones form when substances like calcium, oxalate, or uric acid crystallize in the kidneys. - **Etiology**: Risk factors include dehydration, high-sodium or high-oxalate diets, genetic predisposition, and certain medical conditions (e.g., gout). - **Types**: Calcium oxalate, uric acid, struvite, cystine. - **Manifestations**: Severe flank pain, hematuria, nausea, vomiting, and painful urination. **7. Causes of Urinary Tract Obstructions** - **Pathophysiology**: Obstructions block the normal flow of urine, leading to pressure buildup, possible infection, and kidney damage. - **Etiology**: Causes include kidney stones, tumors, enlarged prostate, or congenital abnormalities. - **Manifestations**: Painful urination, frequent urge to urinate, hematuria, and possible urinary retention. **8. Cystitis** - **Pathophysiology**: Inflammation of the bladder, often caused by bacterial infection. - **Etiology**: Most commonly caused by **E. coli** from the gastrointestinal tract, but can also be caused by viruses or fungi. - **Manifestations**: Frequent, painful urination, lower abdominal discomfort, and cloudy, foul-smelling urine. **9. Pyelonephritis** - **Pathophysiology**: A kidney infection usually ascending from the bladder, causing inflammation and possible kidney damage. - **Etiology**: Often caused by **E. coli**; risk factors include urinary tract obstruction, pregnancy, or diabetes. - **Manifestations**: Fever, flank pain, dysuria, nausea, and vomiting. **10. Protective Mechanisms to Decrease UTI** - **Pathophysiology**: Normal urinary tract has mechanisms like acidification of urine, mucosal immunity, and efficient urine flow to prevent infection. - **Etiology**: UTI risk increases when these mechanisms are compromised by factors like obstruction, poor hygiene, or weakened immune systems. - **Manifestations**: Infections lead to symptoms like pain during urination, urgency, and frequent urination. **11. Glomerulonephritis** - **Pathophysiology**: Inflammation of the glomeruli that can impair filtration. - **Nephrotic Syndrome**: Characterized by significant protein loss, edema, hyperlipidemia, and hypoalbuminemia. - **Etiology**: Often caused by infections, autoimmune diseases, or systemic conditions like diabetes. - **Manifestations**: Swelling (especially in the legs and around the eyes), foamy urine, weight gain. - **Nephritic Syndrome**: Characterized by hematuria, hypertension, and oliguria. - **Etiology**: Commonly caused by post-streptococcal infection. - **Manifestations**: Blood in the urine, decreased urine output, and high blood pressure. **12. Acute Tubular Necrosis** - **Pathophysiology**: Damage to the tubules of the kidneys, typically due to ischemia or nephrotoxins. - **Etiology**: Causes include prolonged hypotension, certain medications (e.g., NSAIDs, antibiotics), or toxins. - **Manifestations**: Oliguria or anuria, elevated creatinine, and electrolyte imbalances (hyperkalemia, acidosis). **13. Acute Renal Failure** - **Pathophysiology**: A rapid decline in kidney function, leading to the retention of waste products. - **Phases**: - **Initiation**: The onset of injury. - **Oliguric**: Reduced urine output and increased serum creatinine. - **Diuretic**: Increased urine output as the kidneys begin to recover. - **Recovery**: Gradual improvement in kidney function. - **Diagnostics**: Blood tests (e.g., creatinine, BUN), urine output measurement, and imaging studies. - **Etiology**: Ischemia, nephrotoxins, infections, or obstruction. - **Manifestations**: Decreased urine output, swelling, confusion, fatigue, nausea. **14. Chronic Renal Failure** - **Pathophysiology**: Gradual loss of kidney function over months to years. - **Etiology**: Common causes include diabetes mellitus, hypertension, and glomerulonephritis. - **Manifestations**: Symptoms include fatigue, swollen ankles, high blood pressure, and uremic symptoms (itching, nausea). **15. Neurological Control of Bladder Function** - **Pathophysiology**: Bladder control is mediated by the **autonomic nervous system**, specifically the parasympathetic (for bladder contraction) and sympathetic (for bladder relaxation) systems. - **Etiology**: Disruptions in the nerve pathways (e.g., spinal cord injury, neurological diseases) can impair bladder control. - **Manifestations**: Involuntary urination, difficulty emptying the bladder, or inability to initiate urination. **16. Types of Incontinence** - **Stress Incontinence**: Leakage due to increased intra-abdominal pressure (e.g., coughing, sneezing). - **Urge Incontinence**: Sudden, intense urge to urinate with involuntary leakage. - **Overflow Incontinence**: Involuntary leakage due to bladder overfilling. - **Functional Incontinence**: Inability to reach the toilet in time due to physical or cognitive limitations. **17. Neurogenic Bladder** - **Pathophysiology**: A condition where nerve damage affects bladder control, leading to problems with voiding or retaining urine. - **Etiology**: Often caused by spinal cord injuries, multiple sclerosis, stroke, or diabetes. - **Manifestations**: Difficulty initiating urination, incomplete emptying, urinary retention, or incontinence