Renal Dysfunction

List causes of urinary tract obstruction

Interference of flow of urine at any site along tract and urine accumulates

causes =

• tumors (benign prostatic hyperplasia or carcinomas)

• stones - calculi (inflammation of gi tract)

• trauma (loss of peristalsis)

• pregnancy (loss of bladder muscle function

• neurogenic bladder (edema)

The outcome of obstruction is

compression of the kidney structures from accumulation of urine, with ischemic atrophy of the papilla and medulla. May result in failure to concentrate urine and large amount of dilute urine.

Major types of stones

1. Calcium = 75-80% of stones. Idiopathic, often found in middle aged men with family history. Association with hypercalciuria, hyoeruricosuria, and prolonged immobilization

2. Struvite = 15% of stones. Crystals of magnesium, ammonium phosphate - precipitated by urea- splitting organisms (Pseudomonas and Proteus) found in alkaline urine, common in women

3. Uric Acid stones (gout) = Caused by high levels of uric acid in the urine, due to high purine diets (meat/fish/poultry) and concentrated acidic urine

Major clinical manifestation of renal calculi is

• pain which will vary in location and severity

• the pain can be severe and require narcotic analgesia for relief

Treatment of renal calculi and goal of treatments

Goal: is to prevent new stone formation and to reduce the size of stones that have already formed

1. reduce stone forming substances in urine through diet changes and high fluid intake

2. altering pH of urine

3. surgical removal

4. lithrotripsy (high energy shock waves fragment stones for excretion

5. lasers - break up stones

6. urethral catheters - inserted past the obstruction

7. nephrostomy tube - may be inserted into the renal pelvis

Describe the neurogenic bladder

Urinary tract obstruction caused by an interruption of the nerve supply to the bladder. Characterized by underactive bladder function

• upper motor neuron lesion causes loss of voluntary control of voiding

• lower motor neuron lesions cause loss of both voluntary and involuntary control of urination

What is the neurogenic bladder commonly associated with?

Usually associated with infection due to:

• bladder distention and urine retention

• placement of catheters

• development of stones caused by bone resorption due to physical immobility

• development of a fever frequently accompanied by chills, shivering, bacteriruia

What is the most common renal neoplasm & their clinical manifestations

Renal cell carcinoma = 85%, most common renal neoplasm and represents approx 2% of cancer deaths

• most often in men 50-60 years

• tumors usually occur unilaterally and spread through the lymph nodes and blood vessels

What is the most common cause of urinary tract infection and what microbes are involved?

Caused by bacteria and are diagnosed by culture of urine with counts of 100,000 bacterial per ml of urine

• gram negative E.coli, Klebsiella, Enterobacter

• Pseudomonas or proteus into urethra or bladder

• can occur anywhere along urinary tract

Most common site of UTI and the different types of this inflammation

Cystitis = inflammation of bladder and most common site

1. hyperemic = red mild inflammation

2. hemorrhagic = diffuse hemorrhage

3. suppurative = pus formation

4. ulcerative = sloughing of the bladder mucosa

5. gangrenous = necrosis of the bladder wall

Why do women more commonly develop cystitis?

Shorter urethra, closeness of urethra to the anus, contamination of vaginal secretions

The usual causative organism in acute pyelonephritis

An infection of the renal pelvis. Causative organism usually bacteria refluxed from the bladder (vesiocuretral) - E.coli

Chronic pyelonephritis vs acute pyelonephritis

Chronic = defined as recurrent autoimmune infection of the kidney with inflammation and scarring. more likely to occur in patient who have renal infections associated with some type of obstructive pathologic condition. chronic obstruction prevents elimination of bacteria resulting in progressive inflammation, causing fibrosis and scarring

• pelvis and calyces become dilated and blunted; gradual destruction of the tubules occurs with atrophy and scarring

Acute = infection of the renal pelvis and interstitium. inflammatory process is usually focal and irregular, primarily affecting pelvis, calyces and medulla. This causes infiltration of WBCs, inflammation and purulent urine.

Nephritic vs nephritis (glomerulonephritis) glomerular disease

Nephritic = characterized by hematuria with red cell casts and varying degrees of proteinuria (symptoms)

Nephritis = an inflammation of the glomerulus (most common cause of chronic and end stage renal failure)

How do glomerular disorders affect function?

• Glomerular damage causes a decrease in —> glomerular membrane surface area

• edema - associated with hypoalbuminemia and/or salt and water retention from reduced GFR. May need diuretics or dialysis

• glomerulonephritis - inflammation of the glomerulus that can be caused by immunologic abnormalities, drugs or toxins, vascular disorders, systemic diseases

• glomerulonerphritis - most common cause of chronic and end-stage renal failure

Most frequent cause of acute glomerulonephritis

Caused by post-streptocaoccal infection and it is seen 7-10 days post strep

abrupt onset of symptoms:

• hematuria

• oliguria

• RBC casts

• edema

• proteinuria

• hypertension

• decreased GFR

Good-Pasture Syndrome

Associated with the antibody formation against both pulmonary capillaries and glomerular basement membranes.

• occurs in men 20-30 yrs

• extensive proliferation of cells in bowman’s space with crescent formation

• rapid decline in glomerular function —> failure in a few weeks or months

• prognosis is poor; dialysis or transplantation may be required

Chronic glomerulonephritis

Includes a variety of glomerular diseases with progressive courses leading to renal failure

• pathologic changes seen include:

  • prolifeation of mesangial cells

  • focal or diffuse segmental fibrosis and glomerular deterioration

  • tubular dilation and atrophy

Nephrotic syndrome

The excretion of 3.5 grams or more of protein in the urine per day is a characteristic of glomerular injury. Characterized by proteinuria

May interfere with the immune system

• other clinical findings include:

  • hypoalbuminemia

  • edema

  • lipiduria

  • hyperlipidemia

When does renal failure occur

Decline in renal function is about 25% of normal or a GFR of 25-30 ml/min. When less than 10% of renal function remains = end stage renal failure (ESRF). Can be acute and rapidly progressive (reversible). Slow and chronic over a period of months/years = irreversible

Azotemia and uremia

Azotemia = increased serum urea and creatinine levels

Uremia = elevated creatinine and urea levels, accompanied by fatigue, anorexia, nausea, vomiting, pruritis and neurologic changes

Prerenal vs intralrenal vs postrenal acute failure

Prerenal = caused by impaired renal blood flow (vasoconstriction, hypotension, hypovolemia, hemorrhage, inadequate cardiac output

Intrarenal = may result from acute tubular necrosis, cortical necrosis, acute glomerulonephritis, malignant hypertension, DIC, renal vasculitis

Postrenal = usually occurs with urinary tract obstruction that affects the kidneys bilaterally

Oliguria/anuria and diuresis

oliguira/anuria = may last ½ weems. BUN (blood urea nitrogen) and creatinine levels rise

diuresis = increase in urine volume with fluid losses of 3-4 L/day. Mineral wasting

Primary goal of therapy in renal failure

Goal of therapy = maintain life until renal function as been recovered.

• correcting fluid imbalance

• treating infections

Clinical couse of chronic renal failure

1. asymptomatic; decreased renal reserve

2. renal insufficiency; more than 75% of renal tissue destroyed (GFR is 25% of normal)

3. end stage of renal failure or uremia; approx 90% of nephron mass has been destroyed

• GFR is 10% or less of normal = creatinine and BUN (blood urea nitrogen) increase = patient show symptoms

• death unless transplant or dialysis performed