Chronic Kidney Disease

Question 1

Causes of CKD

Answer 1

Diabetes
Hypertension
Age-related decline
Glomerulonephritis
Polycystic kidney disease
Medications such as NSAIDS, proton pump inhibitors and lithium

Question 2

Risk factors of CKD

Answer 2

Older age
Hypertension
Diabetes
Smoking
Use of medications that affect the kidneys

Question 3

Presentation of CKD

Answer 3

Usually chronic kidney disease is asymptomatic and diagnosed on routine testing. A number of signs and symptoms might suggest chronic kidney disease:

Pruritus (itching)
Loss of appetite
Nausea
Oedema
Muscle cramps
Peripheral neuropathy
Pallor
Hypertension

Question 4

Investigations of CKD

Answer 4

Estimated glomerular filtration rate (eGFR) can be checked using a U&E blood test. Two tests are required 3 months apart to confirm a diagnosis of chronic kidney disease.

Proteinuria can be checked using a urine albumin:creatinine ratio (ACR). A result of ≥ 3mg/mmol is significant.

Haematuria can be checked using a urine dipstick. A significant result is 1+ of blood. Haematuria should prompt investigation for malignancy (i.e. bladder cancer).

Renal ultrasound can be used to investigate patients with accelerated CKD, haematuria, family history of polycystic kidney disease or evidence of obstruction.

Question 5

Staging of CKD

Answer 5

The G score is based on the eGFR:

G1 = eGFR at or above >90
G2 = eGFR 60-89
G3a = eGFR 45-59
G3b = eGFR 30-44
G4 = eGFR 15-29
G5 = eGFR <15 (known as “end-stage renal failure”)

The A score is based on the albumin:creatinine ratio:

A1 = < 3mg/mmol
A2 = 3 – 30mg/mmol
A3 = > 30mg/mmol

The patient does not have CKD if they have a score of A1 combined with G1 or G2. They need at least an eGFR of < 60 or proteinuria for a diagnosis of CKD.

Question 6

Complications of CKD

Answer 6

Anaemia (decrease erythropoietin, decreased production of RBCs)

Renal bone disease (can lead to hypoparathyroidism - may lead to rugger jersey spine)

Cardiovascular disease

Peripheral neuropathy
Dialysis related problems

Question 7

NICE suggest referral to a specialist when there is:

Answer 7

eGFR < 30
ACR ≥ 70 mg/mmol
Accelerated progression defined as a decrease in eGFR of 15 or 25% or 15 ml/min in 1 year
Uncontrolled hypertension despite ≥ 4 antihypertensives

Question 8

Aims of management

Answer 8

Slow the progression of the disease
Reduce the risk of cardiovascular disease
Reduce the risk of complications
Treating complications

Question 9

Slowing the progression of the disease may include?

Answer 9

Optimise diabetic control
Optimise hypertensive control
Treat glomerulonephritis

Question 10

Reducing the risk of complications may include?

Answer 10

Exercise, maintain a healthy weight and stop smoking

Special dietary advice about phosphate, sodium, potassium and water intake

Offer atorvastatin 20mg for primary prevention of cardiovascular disease

Question 11

Treating complications of CKD

Answer 11

Oral sodium bicarbonate to treat metabolic acidosis

Iron supplementation and erythropoietin to treat anaemia

Vitamin D to treat renal bone disease

Dialysis in end stage renal failure

Renal transplant in end stage renal failure

Question 12

Treating Hypertension in CKD

Answer 12

ACE inhibitors are the first line in patients with chronic kidney disease. These are offered to all patients with:

Diabetes plus ACR > 3mg/mmol
Hypertension plus ACR > 30mg/mmol
All patients with ACR > 70mg/mmol
Aim to keep blood pressure <140/90 (or < 130/80 if ACR > 70mg/mmol).

Serum potassium needs to be monitored as chronic kidney disease and ACE inhibitors both cause hyperkalaemia.

Question 13

Anaemia of Chronic Kidney Disease Pathophysiology

Answer 13

Healthy kidney cells produced erythropoietin. Erythropoietin is the hormone that stimulates production of red blood cells. Damaged kidney cells in CKD cause a drop in erythropoietin. Therefore there is a drop in red blood cells and a subsequent anaemia.

Anaemia can be treated with erythropoiesis stimulating agents such as exogenous erythropoeitin. Blood transfusions should be limited as they can sensitise the immune system (“allosensitisation”) so that transplanted organs are more likely to be rejected.

Iron deficiency should be treated before offering erythropoetin. Intravenous iron is usually given, particularly in dialysis patients. Oral iron is an alternative.

Question 14

Renal Bone Disease in CKD is known as?

Answer 14

chronic kidney disease-mineral and bone disorder (CKD-MBD).

Question 15

Features of CKD-MBD?

Answer 15

Osteomalacia (softening of bones)
Osteoporosis (brittle bones)
Osteosclerosis (hardening of bones)

Question 16

Xray Changes of CKD-MBD?

Answer 16

Spine xray shows sclerosis of both ends of the vertebra (denser white) and osteomalacia in the centre of the vertebra (less white). This is classically known as “rugger jersey” spine after the stripes found on a rugby shirt.

Question 17

Pathophysiology of CKD-MBD

Answer 17

High serum phosphate occurs due to reduced phosphate excretion. Low active vitamin D because the kidney is essential in metabolising vitamin D to its active form. Active vitamin D is essential in calcium absorption from the intestines and kidneys. Vitamin D also regulates bone turnover.

Secondary hyperparathyroidism occurs because the parathyroid glands react to the low serum calcium and high serum phosphate by excreting more parathyroid hormone. This leads to increased osteoclast activity. Osteoclast activity lead to the absorption of calcium from bone.

Osteomalacia occurs due to increased turnover of bones without adequate calcium supply.

Osteosclerosis occurs when the osteoblasts respond by increasing their activity to match the osteoclasts by creating new tissue in the bone, however due to the low calcium level this new tissue is not properly mineralised.

Osteoporosis can exist alongside the renal bone disease due to other risk factors such as age and use of steroids.

Question 18

Management of CKD-MBD involves a combination of:

Answer 18

Active forms of vitamin D (alfacalcidol and calcitriol)

Low phosphate diet

Bisphosphonates can be used to treat osteoporosis

Question 19

Definition of CKD?

Answer 19

Reduction in kidney function for 3 or more months

eGFR <60
or
ACR >3 (urine albumin to creatinine ratio) also known as microalbumin

Question 20

Peritoneal dialysis

Answer 20

Peritoneal membrane is filtering membrane

Dialysis solution added to peritoneal cavity (contains dextrose)

Continuous ambulatory peritoneal dialysis
- No machine, dialysis solution in peritoneum all times

Automated Dialysis
- Machine carries out dialysis over night (8-10hrs)

Question 21

Haemodialysis

Answer 21

Various regimes

Can be hospital or at home

Blood filtered by a haemodialysis machine

Requires an A-V fistula
Surgical operation with 1 to 4 month maturation period
Infections
Increased risks of blood cltos
STEAL syndrome
High output heart failure