Tutorial 7 Kidney disease

Question 1

State the functions of kidney?

Answer 1

1. Filter blood (1.2L/min)
2. Excretes unwanted waste products
   (e. g. toxins and metabolic wastes)
3. Regulate fluid and electrolyte balance

Question 2

Provide examples of alternations/diseases that can occur in the kidney and/or urinary tract

Answer 2

• Cystitis (bladder inflammation)
• Renal calculi (kidney stones)
• Acute renal injury
• Glomerulonephritis
• Chronic kidney disease
• Urinary tract infection
• Pyelonephritis (UTI that has reached the pelvis of the kidney)
• Hydroureter
• Nephroblastoma (Wilm’s tumour occurs more frequently in children)
• Polycystic kidney disease
• Stricture or obstruction of the urethra (think prostate enlargement)
• Renal colic (may be caused by renal calculi)

Question 3

Define the term urinary tract obstruction

Answer 3

1. a blockage of the passage of urine

2. It can occur at any site along the urinary tract

Question 4

Outline how the severity of obstructive uropathy is classified

Answer 4

1. Obstructive uropathy refers to anatomical changes that occurred as a result of a blockage
2. The severity of obstruction is determined by:
   a. examine the location of the obstruction
   b. whether the obstruction affects one or both kidneys
   c. the completeness of the obstruction
   d. how long the blockage has existed
   e. the nature of the obstruction

Question 5

Describe the common causes of the upper urinary tract obstruction

Answer 5

1. Common causes include:
   a. narrowing of a ureter or urethra (stricture)
   b. compression due to either a congenital defect or physical compression from a blood vessel, scarring, tumour or abdominal inflammation
   c. renal calculi (kidney stones)
   d. malignancy in either the renal pelvis, ureter, prostate or bladder

Question 6

What short term effects would the upper urinary tract obstruction have on kidney?

Answer 6

1. The effects would depend on the size of the obstruction
2. Initially the urine backs up, which leads to the dilution of the ureter, renal pelvis and calyces. Dilution occurs close to the site of the urinary blockage.
3. Within 14 days, the obstruction will have affected both the proximal and distal part of the nephron
4. Within 28 days, this backflow of urine will lead to the glomeruli becoming damaged, and consequently, the renal cortex and medulla will decrease in size.
5. Total obstruction = leads to damage to the renal tubule in 4 hours and is irreversible is not corrected within 4 weeks
6. If the obstruction is identified promptly and treated, the kidney may recover function within 2 months
7. Partial blockage may go unnoticed and therefore are more likely to go untreated, leading to irreversible damage which may result in AKI and AKF

Question 7

What effect would a total obstruction in the ureter have on fluid and electrolyte balance?

Answer 7

1. Backflow of urine into the tubules changes pressure gradient and reduces GFR (reduced urine output)
2. Less blood enters the tubule as filtrate and is retained in the circulation
3. Retention of sodium and fluid = increased BP and oedema
4. Retention of potassium = hyperkalaemia (can affect cardiac function)
5. Retention of H+ = metabolic acidosis

Question 8

What are kidney stones (renal calculi)?

Answer 8

1. renal calculi are formed in the kidney
2. They may be caused by a collection of crystals (70-80% are either calcium oxalate or calcium phosphate), struvite (15%) or uric acid (7%)

Question 9

What symptoms will a patient with kidney stones exhibit?

Answer 9

1. Patient with renal calculi experience renal colic which is a moderate to severe pain originating in the flank region and radiating to the groin
2. The patient may experience nausea and vomiting
3. Microscopic examination of urine may show the presence of haematuria

Question 10

Describe two common causes of lower urinary obstruction

Answer 10

1. mainly associated with urinary storage in the bladder or problems of urine emptying out of the bladder
2. This is the result of either neurogenic and/or anatomical alterations
3. Incontinence is the most common symptom observed in these patients

Question 11

State what causes urinary tract infection

Answer 11

UTI can be described as the inflammation of the urinary epithelium that has resulted from infection of the urinary tract with bacteria (usually from gut flora)

Question 12

Briefly describe the types of urinary tract infection

Answer 12

1. acute cystitis - infection of the urinary bladder (most common site of a UTI)
   a. generally caused by E.coli although other organisms may also cause infection
   b. individuals may be asymptomatic or they may have urinary frequency, urgency, dysuria and lower back pain
2. Acute pyelonephritis - infection of the renal pelvis and interstitium
3. Chronic pyelonephritis - persistent or recurrent infection that leads to scarring of the kidney

Question 13

Why are urinary tract infections more common in children and the elderly?

Answer 13

1. A UTI is predominantly caused by bacteria that come from gut flora
2. Many people are at risk of UTI including children and the elderly, sexually active and pregnant women, diabetics and those with UT obstruction
3. Children and elderly are more prone to UTI due to several reasons:
   In children, especially girls, hygiene practices may not be well developed and they may wipe incorrectly which introduce gut bacteria into the UT leading to infection

Question 14

Why are urinary tract infection more common in children and the elderly?

Answer 14

1. In the elderly, decreased dexterity may also lead to translocation of bacteria to the UT
2. Decreased oestrogen in elderly women or antibacterial use can also increase the risk of UTI
3. Men are less likely to have a UTI as they have a long urethra and the prostatic secretions also decrease the risk
4. Please note that the elderly will also be asymptomatic or have minimal symptoms
5. UTIs should be investigated in an elderly person who has an elevated temperature or is confused

Question 15

Compare and contrast acute and chronic glomerulonephritis

Answer 15

1. Acute glomerulonephritis is the inflammation within the glomerulus. This inflammation is often a result of the immune reaction following a streptococcal infection.
2. Chronic glomerulonephritis is also inflammation of the glomerulus. However, it is usually due to alternations/diseases, which cause progressive deterioration of glomerular function leading to a loss of total renal function.

Question 16

What is acute kidney injury and what is the RIFLE staging system?

Answer 16

1. AKI is a sudden decline in kidney function (hours to days) and leads to disorder of acid/base, electrolyte and fluid balance.

2. RIFLE stands for:
R - risk
I - injury
F - failure
L - loss
E - end stage renal failure

3. It may be caused by many things including but not limited to hypovolaemia (a prerenal cause), acute tubular necrosis (intrarenal cause), obstructive uropathies (postrenal cause)
4. The clinical progression of AKI has three phases: oliguria, diuresis, and recovery

Question 17

Describe the classification system that used to describe AKI (ARF)

Answer 17

1. Acute kidney injury was formerly known as acute renal failure
2. AKI is commonly defined as an abrupt decline in renal function, clinically manifesting as a reversible acute increase in nitrogen waste products - measured by blood urea nitrogen (BUN) and serum creatinine levels - over the course of hours to weeks
3. AKI (ARK) is observed in 5% of the hospital administration & approx. 30% of ICU admission
4. AKI (ARF) can be divided into three categories:
   a. prerenal - problems with blood supply (hypovolaemia)
   b. intrarenal - damage to kidney (renal tubular necrosus)
   c. postrenal - obstruction in the UT (obstructive uropathies)

Question 18

What are the major causes of prerenal AKI (ARF)?

Answer 18

1. Hypovolaemia (volume depletion)
   e. g. haemorrhage, vomiting, renal fluid loss via diuretic drugs
2. Low cardiac output
   e. g. diseases of the myocardium, pulmonary hypertension, massive pulmonary embolus
3. Alterations in renal system vascular resistance ratio
   e. g. anaphylaxis, renal vasoconstriction, cirrhosis with ascites (hepatorenal syndrome)
4. Renal hypoperfusion
   e. g. ACE (Angiotensin-converting enzyme) inhibitors, atherosclerosis plaque, thrombosis
5. Hyperviscosity syndrome
   e. g. polycythaemia

Question 19

What are the major causes of intrarenal/intrinsic AKI (ARF)?

Answer 19

1. Diseases of the glomeruli or renal microvasculature
   e. g. SLE, glomerulonephritis
2. Acute tubular necrosis
   e. g. ischaemia, toxins
3. Interstitial nephritis
   e. g. NSAIDs, lymphoma, cytomegalovirus

Question 20

Describe the pathophysiology of acute tubular necrosis

Answer 20

1. Acute tubular necrosis is the death of tubular cells
2. May result from:
   a. lack of O2 (ischaemic ATN)
   b. exposure to toxic drug or molecule (nephrotoxic ATN)
3. New tubular cells normally replace those that have died
4. May be mistaken for prerenal AKI (ARF)

Question 21

Why is dialysis often required in acute tubular necrosis?

Answer 21

1. Dialysis may be required as waste products can no longer be excreted effectively and electrolyte and fluid reabsorption/excretion is affected
2. Unlike prerenal acute kidney failure, ATN does not rapidly improve following the administration of large-volume intravenous fluid because the kidneys have lost their ability to handle fluids and administration of fluids can lead to the patient experiencing fluid overload

Question 22

What are the major causes of postrenal AKI (ARF)?

Answer 22

obstruction:

a. calculi
b. cancer causing an obstruction
c. prostatic hypertrophy
d. stricture of the urethra

Question 23

Describe the clinical signs of prerenal AKI (ARF)

Answer 23

1. Symptoms are associated with the underlying cause:
   a. thirst
   b. tachycardia
   c. orthostatic dizziness
   d. reduced JVP (jugular venous pressure)
   e. reduced axillary sweating
   f. dry mucous membranes
2. In addition, patients may have oliguria and flank pain but it may not always be present

Question 24

What are the clinical signs of intrarenal AKI (ARF)?

Answer 24

1. Ischaemic and nephritic causes constitute 90% of causes
2. Signs are related to the complications associated with renal failure
3. Fever, joint pain, flank pain, headache, dizziness, confusion, seizure, oliguria (reduced urination), oedema, hypertension, heart failure

Question 25

Describe the clinical signs of postrenal AKI (ARF)

Answer 25

1. suprapubic and flank pain

2. colicky pain

Question 26

How would you diagnose AKI (ARF)?

Answer 26

1. History
2. Drug charts
3. Physical examination
4. Urinalysis
5. Routine blood tests - biochemical status & general health

Question 27

Define the term Chronic Renal Failure (CRF)/Chronic Kidney Disease (CKD)

Answer 27

1. CRF = progressive loss of kidney function
2. The destruction of renal mass with irreversible sclerosis and loss of nephrons leading to a progressive decline in GFR
3. CRF is clinically indicated by kidney damage or a decreased kidney glomerular filtration rate (GFR) for more than 3 months

Question 28

Describe the five stages and treatment of chronic kidney disease

Answer 28

1. Stage 1: The kidney has an amazing ability to compensate for reductions in nephron function. Therefore, the patients with stage one kidney failure may not be identified initially. They will have a relatively normal or high GFR (>90mL/min). At this point, the patients’ BP will be measured, level of proteinuria determined and urinalysis conducted.
2. Stage 2: The patient will exhibit mild kidney damage and will have a mild reduction in GFR. Urinalysis should be conducted and cardiovascular risk reduction implemented.
3. Stage 3: Moderate kidney damage with a GFR (30-59mL/min). At this stage, the patient’s GFR should be monitored every 3 months, nephrotoxins should be avoided, ACE inhibitors may be required, drug dosages need to be adjusted due to changes in excretion.
4. Stage 4: Severe kidney damage has occurred and the GFR will be low (15-29mL/min). Patients will need to be treated by a renal specialist and start treatment both physical and psychological to prepare for dialysis and transplant.
5. Stage 5: This is referred to as end stage kidney disease and the kidney has a GFR of <15mL/min. The patient will need a transplant and dialysis at this stage. Potassium and protein in the diet will need to be carefully monitored.

Question 29

What are the clinical manifestations of CKD?

Answer 29

1. The manifestations of CKD are described as uremia, which is the accumulation of nitrogenous wastes from protein metabolism as well as systematic effects caused by the accumulations of toxins in the bloodstream.
2. Specific problems include:
   a. A rise in serum creatinine and decreased creatinine clearance rates
   b. Sodium and fluid retention = oedema and hypertension
   c. If the body cannot get rid of excess fluid, this can lead to hyponatremia (sodium is diluted)
   d. Hyperkalaemia (think electrolyte balance between hydrogen, potassium and sodium). This is the main cause of death for people who miss dialysis sessions.
   e. Alterations in calcium and phosphate metabolism leading to hypocalcemia. Renal phosphate excretion decreases which lead to phosphate binding to calcium thus further perpetuating hypocalcaemia.

Question 30

Complications of CKD

Answer 30

1. Hyperlipidaemia is common as uraemia leads to a reduction of lipoprotein lipase, which results in a reduction of HDLs. Thus atherosclerosis and vascular calcification are accelerated.
2. Decrease in erythropoietin leads to anaemia
3. Immune responses decrease and increase the risk of infection. Factors such as malnutrition, hyperglycemia and metabolic acidosis increase the immunosuppression.
4. Neurological symptoms, which may progress to seizure and coma, may result from electrolyte imbalance and uraemia.
5. Insulin resistance is common in uraemia

Question 31

Describe the pathophysiology of CKD (CRF)

Answer 31

1. In CRF, the kidneys attempt to compensate for renal damage by hyperfiltration.
2. Hyperfiltrations, through nephrons, causes further loss of function.
3. Chronic loss of functions causes generalised wasting and progressive scarring within all parts of the kidneys.
4. CRF may not be identified until over 70% of the normal combined function of both kidneys is lost.

Question 32

Name causes of CRF (CKD)

Answer 32

Most common causes are hypertension and diabetes

Question 33

State the cause of Pre, Intra, & Post renal CRF

Answer 33

1. Pre: sudden reduction in blood flow in the kidney
   a. poor cardiac function
   b. chronic liver failure
   c. atherosclerosis of the renal arteries
2. Intra: changes within the kidneys
   a. e.g. diabetic nephropathy - most common
   b. chronic glomerular nephritis
   c. vasculitis
   d. polycystic kidney disease
3. Post: obstruction can cause urinary backflow and put pressure on the kidney
   e. g. kidney stones, bladder outlet obstruction, retroperitoneal fibrosis

Question 34

What clinical indicators may be used to determine if a patient has CRF (CKD)?

Answer 34

1. Rise in serum creatinine concentration
2. Azotaemia (a rise in blood urea nitrogen (BUN) concentration)
3. Disturbances in ECF, electrolyte and acid/base homeostasis
4. Oliguria is a common finding but is not always present
5. May be asymptomatic

Question 35

What risk factors increase the likelihood of the development of renal carcinoma in a patient?

Answer 35

1. 2.3% of all Australian cancers
2. It is twice as common in men than women, with approximately 850 people dying from it each year.
3. Althought the aetiology is unknown, a moderate association has been identified between smoking, tobacco, hypertension and obesity and the incidence of renal carcinoma.

Question 36

What is dialysis and how does it compensate for decreased kidney function?

Answer 36

1. There are two types of dialysis:
   peritoneal dialysis & haemodialysis
2. In peritoneal dialysis, a catheter is inserted into the abdomen filling the peritoneal cavity with dialysis solution. The peritoneal membrane is very thin and acts like a filter allowing waste products to pass from the blood vessels in the peritoneum into the dialysate solution.
3. The dialysis fluid is then drained and the used solution containing waste product is thrown away. The process of draining and filling is called the exchange and this takes approximately 30 minutes to complete.
4. Most patients are required to have four exchanges a day with the solution remaining in the abdomen for 4 to 6 hours. This form of peritoneal dialysis is called continuous ambulatory peritoneal dialysis (CAPD). Peritoneal dialysis can also be conducted at night using a machine and is called cycler assisted peritoneal dialysis (CCPD).

Question 37

Haemodialysis

Answer 37

1. Haemodialysis is a procedure that cleans and filters a patient’s blood. It removes nitrogen wastes, extra salt and fluid. It also helps the body to maintain blood pressure and keep the right balance of potassium, sodium and chloride.
2. It removes the blood from an artery usually located in the arm to a machine and then returns to the body via a vein. Haemodialysis uses a dialyser or special filter to clean the patient’s blood.
3. Access to the bloodstream is provided via a fistula, this access can be internal or external to the body. Haemodialysis can be done at home or at the centre.
4. Home dialysis requires special training. Side effects can be caused by rapid changes in fluid and salt concentrations within the body. Muscle cramps and hypotension are two common side effects.

Question 38

What electrolyte imbalances may occur as a result of kidney disease?

Answer 38

1. Hyperkalaemia (kidney cannot excrete potassium) - leads to abdominal cramping, muscle weakness, paralysis and cardiac arrest.
2. Hypernatraemia (kidney cannot excrete excess sodium) - leads to high blood pressure, muscle twitching, weakness and disorientation.
3. Hypermagnesaemia - leads to a decrease in blood pressure, decreased heart rate, coma and cardiac arrest.
4. Hypocalcaemia - leads to muscle spasms, abnormal heart rhythm and seizures.

Note: hyponatraemia is also common in kidney disease indicating that kidney’s ability to concentrate urine is affected.

Question 39

List possible disorders that may lead to the following urine products being present in urine.

Answer 39

Glucose - diabetes mellitus; pancreatic tumours

Blood - from Hb, pyelonephritis; RBC, damaged kidney from accident; from myoglobin, muscle crush injury or strenuous exercise

Protein - glomerulonephritis; damaged renal tubule walls (drug toxicity); cancer (Igs - multiple myeloma)

Ketones - associated with diabetic acidosis although carbohydrate starvation or severe gastric disturbance can also produce it.