Risk factors/Predisposing factors

Acute Renal Failure

• Advanced age
• Chrinic infection
• Diabetes

Diabetes can also damage the kidneys because it may cause:

—fhigh blood pressure

—fhardening of the arteries

—fdamage to the nerves that control the bladder, making it difficult to know when you need to urinate

- repeated urinary tract infections (Bacteria grow rapidly in urine with a high sugar level.)

• High blood pressure

-If left uncontrolled, high blood pressure can damage the kidneys by causing the blood vessels of the kidneys to become thickened and rigid

-This reduces the blood supply, which destroys kidney tissue and significantly impairs the kidneys' ability to cleanse the blood and balance body chemicals

• Kidney diseases
• Liver diseases
• Prostate gland enlargement

f—can block the normal flow of urine, and cause the urine to back up into the kidney

• Bladder outlet obstruction

Obstructions, or blockages, can occur anywhere within the urinary system from the kidney itself to the ureter, bladder or urethra. Some of the causes of blockage

qkidney stones

qan enlarged prostate gland in men

q tumours or blood clots

Even when a blockage is only partial, damage can still occur.

Kidney Stones

- Kidney stones are not a major cause of kidney failure. However, recurrent kidney stones can cause damage to the kidney tissue and contribute to kidney failure

- Most stones begin when a tiny particle of solid material is deposited in calycesà more and more materials are added to the initial pebbleà it enlarges to become a stone.

f —Also, stones often make it easier to get infections in the urinary tract. If have repeated infections and/or scarring from kidney stones, the damage could contribute to decreased kidney function.

Chronic Renal Failure

• Diabetes
• High Blood Pressure
• Bladder outlet obstruction
• Lupus Erythematosus

—This condition is known as an autoimmune disease. Normally, the body's immune system makes proteins, called antibodies, which protect the body against infections and foreign materials, called antigens. In an autoimmune disorder, the immune system begins to destroy own tissues and organs because it cannot tell the difference between a foreign substance and the tissue of your body

—family history and environmental factors (e.g., infections, viruses, and toxic chemicals) may play key roles

• Chronic Glomerulonephritis

-—This disease causes inflammation of the part of the kidney that filters the blood, the glomeruli

—-Glomerulonephritis may be acute or chronic

—-Acute glomerulonephritis usually develops suddenly, often following an infection in the throat (such as strep throat) or on the skin. The problem usually is related to a malfunction in the immune system. The antibodies produced by the body to fight the infection persist after the bacteria have been destroyed, and these antibodies begin to damage the kidneys.

• Congenital Kidney disease

—These defects can range from absence of one or both kidneys to abnormalities in the position, form, size or structure of the kidneys and other parts of the urinary system.

—most common congenital problems

vdefects in the ureters (the tubes that carry urine from the kidneys to the bladder)

vurethra (the tube that drains urine from the bladder during urination)

These defects can block the normal flow of urine, causing urine to back up, or "reflux" to the kidneys. These problems are among the more common causes of kidney failure in children

• Family history of kidney disease

—Polycystic Kidney Disease (PKD)

÷The adult type, which is called autosomal dominant PKD, or ADPKD, occurs when an abnormal gene is inherited from one parent. The childhood variety, which is called autosomal recessive PKD, or ARPKD, occurs when both parents pass an abnormal gene to the child.

—-Polycystic kidney disease is characterized by the growth of cysts (soft, fluid filled sacs) that form in the kidney and other organs, such as the liver and pancreas. Outpouchings may also occur in the large intestine and blood vessels of the brain.

-—The cysts enlarge over time, and eventually, they can replace the kidney tissue, reducing kidney function and, in some cases, leading to kidney failure. The kidneys enlarge as the cysts enlarge, and they can weigh more than 20 pounds toward the end of the process.

Alport Syndrome

—-inherited form of kidney inflammation (nephritis)

—-mutation in a gene for a protein in connective tissue, called collagen

—-genetic condition characterized by kidney disease, hearing loss, and eye abnormalities

-—most often affects males

• Urinary Tract Infections

—occur when bacteria get into the urinary tract and cause symptoms such as pain, fever and an increased need to urinate. Usually, these infections remain in the bladder, but they sometimes spread to the kidney.

• Exposure to drugs and toxins

—Using large amounts of certain pain relievers may cause a risk of kidney damage called analgesic nephropathy. This is especially true for pain relievers that combine more than one active ingredient in one pill.

The kidneys get direct exposure to antibiotics because they are the pathway for eliminating these drugs from the body. The longer the kidneys are exposed to the drugs and the higher the dosages, the greater the chance of possible kidney damage

—Certain chemicals, drugs, or other substances can also harm the kidneys. These are called nephrotoxins.

—Industrial areas may be a source of environmental nephrotoxins, such as heavy metals (lead, cadmium, bismuth, arsenic, copper and mercury), carbon tetrachloride, ethylene glycol, trichloroethylene, carbon monoxide, and chlorinated hydrocarbons. Snake venom and certain mushrooms can also destroy kidney tissue.

References:

MedlinePlus

—http://www.nlm.nih.gov/medlineplus/ency/article/000521.htm

—http://www.nlm.nih.gov/medlineplus/ency/article/000504.htm

National Kidney Foundation Inc

—http://www.kidney.org/patients/plu/plu_intro/pluo_5.cfm

—http://ghr.nlm.nih.gov/condition=alportsyndrome

Renal function

Kidney is located around vertebra L2.
Nephron: Glomerulus, proximal convulated tubule, Loop of Henle, distal convulated tubule, collecting duct.
Renal function
1)Conversion of calcidiol to calcitriol (vitamin D3). Raises blood concentration of calcium by promoting intestinal absorption and slightly inhibiting loss in urine. More calcium available for bone deposition.
2)Secretes renin, converting angiotensinogen to angiotensin 1. Angiotensin-converting enzyme on the lining of blood capillaries converts it to angiotensin 2. This hormone causes vasoconstriction.
3)Secretes 85% of the body’s erythropoietin. Promotes RBC production and increases oxygen carrying capacity of blood.
4)Filter blood plasma, separates and eliminates waste from the blood.
5)Regulate blood volume and pressure
6)Regulate osmolarity of body fluids
7)In extreme starvation, they carry out gluconeogenesis by deaminating amino acids and excreting the amino group as ammonia.

Excretion will be explained during PCL =) need to do it with pics.

Prevention

·         Fluid balances will be carefully monitored.

o    Your intake and output will be measured, and you may be weighed every day.

o    Your blood pressure will be checked frequently. You may be given IV fluids to help maintain normal blood pressure.

·         You will have frequent blood tests to make sure your electrolytes are in the proper balance.

·         Your diet will be managed to make sure that you receive at least 100 grams of carbohydrates each day. The amount of protein in your diet may be restricted.³

·         Your medicines will be carefully checked. Medicines that contain magnesium may be stopped. The dosages of your other medicines may be adjusted.

Pathophysiology of Renal Failure

Pathophysiology of renal failure

Renal Failure:

Acute

Chronic

Acute renal failure

Occurs in 3 clinical patterns: 

(1) as an adaptive response to severe volume depletion and hypotension, with structurally intact nephrons; 

(2) in response to cytotoxic, ischemic, or inflammatory insults to the kidney, with structural and functional damage; and 

(3) with obstruction to the passage of urine.

Thus classified as prerenal, intrinsic, and postrenal  

Prerenal Failure

Problems lie in the inability of the circulatory system to deliver the proper perfusion to the kidney to produce a normal GFR (90 - 120 mL/min )

Causes:

a) hypovolemic states (haemorrage, dehydration)

b) impairment of renal autoregulation (seen with cyclooxygenase inhibitors like NSAIDs and aspirin, or angiotensin converting enzyme (ACE) inhibitors)

c) low effective plasma flow state (low cardiac output states –arrythmias, valvular disease, congestive heart failure, systemic vasodilation – sepsis, antihypertensives, congestion – cirrhosis with ascites -> hepatorenal syndrome)

Kidneys recover rapidly once underlying deficit is corrected

Intrinsic Renal Failure

Hallmark: structural injury (most common form – acute tubular injury (ATN), either ischemic or cytotoxic)

Initial phase of ischemic injury – loss of integrity of actin cytoskeleton leads to flattening of the epithelium, with loss of brush border, loss of focal cell contacts, and subsequent disengagement of the cell from the underlying substratum.

Inflammatory response is responsible for some features of ATN

Reduced GFR – caused by intrarenal vasoconstriction (mediators are unknown)

Urine backflow and intratubular obstruction (from sloughed cells and debris) are causes of reduced net ultrafiltration

hallmark of ATN is a failure to maximally dilute or concentrate urine (isosthenuria).

The injured kidney fails to generate and maintain a high medullary solute gradient because the accumulation of solute in the medulla depends on normal distal nephron function.

Glomerulonephritis can be a cause of AKI and usually falls into a class referred to as rapidly progressive glomerulonephritis (RPGN). The pathologic correlation of RPGN is the presence of glomerular crescents (glomerular injury) on biopsy; if more than 50% of glomeruli contain crescents, this usually results in a significant decline in renal function. Although comparatively rare, acute glomerulonephritides should be part of the diagnostic consideration in cases of AKI.

Postrenal Failure

Hallmark: severe urinary tract obstruction

Men: prostate enlargement from benign prostatic hyperplasia or prostate cancer

Women: cervical cancer

Other causes: 

obstruction by bladder, kidney stones (lodged in the urinary tract such that flow from both kidneys is obstructed), phimosis (non-retractable foreskin), neurogenic bladder

Chronic renal failure

Involves several stages 

Decreased renal reserve -> Renal insufficiency -> End-stage renal failure/uremia

Decreased renal reserve

Around 60% nephrons lost

Decrease in GFR

Serum creatinine levels consistently higher than average but within normal range (0.8 to 1.4 mg/dL )

Serum urea levels normal (blood urea nitrogen: 7 to 20 mg/dL) 

No apparent clinical signs

Renal insufficiency

Around 75% nephrons lost

Indicated by a change in blood chemistry and manifestation

GFR decreased to 20% normal

Significant retention of nitrogen wastes (urea and creatine) in the blood

Tubule function decreased

Results in failure to concentrate the urine and control the secretion and exchange of acids and electrolytes.

Osmotic diuresis occurs at the remaining functional nephrons filter an increased solute load

Marked by excretion of large volumes of dilute urine.

Erythropoiesis decreased, patient’s blood pressure elevated (why?)

End-stage renal failure/uremia

More than 90% nephrons lost

Occurs when GFR is negligible

Fluids, electrolytes, and wastes retained in body, all body systems affected

Marked oliguria (reduced urine output) or anuria (no urine output) develops

Investigations

Types of tests and investigations:
1. Urine Test
2. Blood Test
3. Ultrasound
4. Angiography

What can a Urine Test reveal?
 Urine is normally sterile
 Blood cells in urineàmay be a sign of different diseases in the kidneys, the

urinary system or the bladder.
 Glucose in urine à may be a sign of diabetes
 Protein in urineà may be a sign of a kidney disease and can be used to detect the early signs of kidney damage from long-standing diabetes.

Types of urine collection
 24-hour urine collection
 Clean catch urine specimen
 Important! Stop some of the medication before urine tests as drugs may affect the results of test.

24-hour urine collection
 Collect urine for 24 hours.
 Normal resultsà800 to 2000 milliliters per day (with a normal fluid intake of about 2 liters per day)
 Abnormal results:
 Reduced urination à dehydration, inadequate fluid intake, or renal insufficiency or failure.
 Increased urination à Diabetes, end-stage renal disease, high fluid intake, kidney failure

Clean Catch Urine Culture
 About 1 - 2 ounces of urine is needed for a test.
 Remove the container from the urine stream without stopping the flow. Individual may finish urinating into the toilet bowl.
 Sample is sent to the lab.
 Clean Catch Urine Specimen can be used for urine specific gravity.

Urine Specific Gravity
 Requires clean catch urine specimen
 Used to evaluate body's water balance and urine concentration
 Normal values are between 1.002 to 1.028.

Urine pH
 Clean Catch Urine Specimen
 Measure the acidity of urine
 Normal Range: 4.6-8.0
 High pH à Kidney Failure, UTI
 Low pH à emphysema

RBC in Urine
 Clean catch urine specimen
 Normal values are 4 RBC per high power field (RBC/HPF) or fewer. Normal value ranges may vary slightly among different laboratories.
 Greater than normal value: cystitis, pyelonephritis, kidney tumor, kidney stones, glomerulonephritis.

Blood Test
 Blood sample can be analyzed for creatinine, estimated glomerular filtration rate and blood urea nitrogen (BUN)
 The level of these waste products in the blood increases as kidney filtration declines.

Creatinine
 The breakdown product of creatine, which is an important part of muscle.
 The normal value is 0.8 to 1.4 mg/dL.
 Females usually have lower creatinine than males, because they usually have less muscle mass.

Higher than normal results:
 Glomerulonephritis
 Kidney failure
 Pyelonephritis
 Reduced kidney blood flow (shock, congestive heart failure)
 Urinary tract obstruction

Glomerular Filtration Rate
 Used to check how well the kidneys are working
 A formula is used to get the results, where age, gender, height, weight and race are taken into account
 According to the National Kidney Foundation(US), the normal results range from 90 - 120 mL/min.
 Older people will have lower normal GFR levels, because GFR decreases with age.
 Normal value ranges can vary slightly among different laboratories.

Blood Urea Nitrogen (BUN)
 Also to check kidney function
 Normal result: 7 - 20 mg/dl.
 Abnormal results (higher)à hypovolemia, kidney failure, glomerulonephritis, pyelonephritis, acute tubular necrosis, UT obstruction

Angiography
• X-ray examination that shows blood flow in the arteries and veins.
• Needle inserted into artery
• Femoral artery usually used
• Needle is in place, long thin guide wire guided into blood vessle that needs to be examined (using fluorescent screen)
• Catheter is slipped over it pushed along until tip is in the right position
• Guide wire removed and dye injected
• Image viewed on screen / rapid sequence of X-ray pictures for further investigation (flouroscopy)


References:
http://www.netdoctor.co.uk/health_advice/examinations/urinesample.htm
http://www.nlm.nih.gov/medlineplus/ency/article/003425.htm
http://www.nlm.nih.gov/medlineplus/ency/article/007305.htm
http://www.nlm.nih.gov/medlineplus/ency/article/003777.htm