Introduction to Renal Medicine

Question 1

What other specialties are affected by renal medicine?

Answer 1

1. endocrinology - diabetic nephropathy
2. hepatology - hepatorenal failure
3. cardiology - cardiorenal syndrome
4. haematology - myeloma

Question 2

What is cardiorenal syndrome?

Answer 2

Decreases blood supply to the kidneys

Question 3

How does myeloma affect the kidney?

Answer 3

Protein is deposited in the kidney

Question 4

What is a nephron?

How many are in each kidney?

Answer 4

A nephron is a filtering unit

There are around 1 million in each kidney, but the exact number is not known as nephrons are present from birth

Question 5

What happens to urine produced in the kidneys?

Answer 5

It passes through the ureter into the bladder

Question 6

What supplies the glomerulus?

Answer 6

Afferent arterioles coming from the renal artery

Question 7

What happens to blood supply after it has entered venules?

Answer 7

The venules drain into the renal vein to be returned to the heart

Question 8

How long would it be if nephrons from each kidney were placed end to end?

Answer 8

16 kilometers

Question 9

What are the 2 broad functions of the kidney?

Answer 9

1. homeostasis

2. hormone secretion (endocrine)

Question 10

What is meant by homeostasis?

Answer 10

Maintenance of “milieu interieur”

This is a constant internal environment in the body

Question 11

What types of hormones are secreted by the kidneys?

Answer 11

Erythropoietin

Question 12

What is the role of erythropoietin?

Answer 12

It is secreted by the kidneys to stimulate red blood cell production

Question 13

When may a patient inject erythropoietin?

Answer 13

To increase their red blood cell count if they are anaemic

Question 14

How are the kidneys important in fluid and electrolyte balance?

Answer 14

1. volume status
2. electrolyte levels
3. osmolarity

Question 15

What is meant by volume status?

Answer 15

Kidneys regulate the fluid balance in the body through urine production

Question 16

What electrolyte levels are the kidneys important in controlling?

Answer 16

1. sodium
2. potassium
3. urea
4. creatinine

Question 17

What can very high potassium levels lead to?

What is this condition called?

Answer 17

It is a medical emergency which can lead to the heart stopping

It is called hyperkalaemia

Question 18

What is meant by osmolarity?

Answer 18

The concentration of particles exerting an osmotic pressure

e.g. glucose

Question 19

What is significant about the kidneys controlling osmolarity?

Answer 19

The blood usually runs at a certain osmolarity

That allows cells to function well

Confusion, seizures and coma result if osmolarity is not controlled well

Question 20

How are the kidneys involved in maintaining acid-base balance?

Answer 20

They maintain an optimum pH for cellular function

The kidneys regenerate bicarbonate and bring it back into the blood stream

They remove acid

Question 21

What can result from poor kidney function, affecting the pH?

Answer 21

Acidemia/acidosis

This is because not as much bicarbonate is being regenerated

Question 22

How are the kidneys involved in removal of small molecules?

Answer 22

They remove sugars and amino acids

Question 23

What may glucose in the urine indicate?

Answer 23

Disease of the kidneys

1. diabetes mellitus

(caused by a high sugar concentration which the kidneys cannot deal with)

2. tubular disorders

(caused by normal blood sugar level, but dysfunctional kidney)

Question 24

When does loss of amino acids in the urine occur?

Answer 24

In disease of the proximal tubule

Question 25

How is the kidney involved in excretion of waste products and drugs?

Answer 25

It is involved in the removal of nitrogenous waste from protein metabolism 1. urea 2. creatinine from muscle

Question 26

What is used to measure kidney function? What is the drawback of this method?

Answer 26

The level of creatinine in the blood It is not a good way to measure kidney disease as creatinine is not produced by the kidney

Question 27

What determines how much creatinine someone generates?

Answer 27

It depends on an individual's muscle mass

Question 28

What may happen to creatinine when the kidneys aren't functioning?

Answer 28

It accumulates in the blood as it is not being removed However, the "normal" creatinine concentration depends on someone's muscle mass

Question 29

What types of drugs are removed by the kidneys?

Answer 29

1. antibiotics 2. digoxin 3. opiates 4. lithium

Question 30

What happens when a drug is administered to someone with poorly functioning kidneys?

Answer 30

The drug begins to accumulate in the blood This may lead to an overdose in the patient

Question 31

How are the kidneys involved in red blood cell production?

Answer 31

They produce erythropoietin, which stimulates red blood cell production

Question 32

What stimulates red blood cell production?

Answer 32

Hypoxia (low oxygen levels) This may be at an increased altitude

Question 33

Why may recombinant erythropoietin be used?

Answer 33

It decreases the need for blood transfusions as it stimulates RBC production

Question 34

How are the kidneys involved in calcium and phosphate balance?

Answer 34

1. secrete the active form of vitamin D3 | 2. this increases the absorption of calcium from the gut

Question 35

What is the activated form of vitamin D? Where it is produced?

Answer 35

1,25 dihydroxycholecalciferol The first stage occurs in the liver and the second stage occurs in the kidneys

Question 36

What happens to calcium absorption in kidney failure?

Answer 36

You cannot produce 1,25 dihydroxycholecalciferol This means calcium is not absorbed from the gut Calcium levels fall

Question 37

What can low calcium levels lead to?

Answer 37

1. seizures | 2. secondary hyperparathyroidism

Question 38

What is the action of the parathyroid glands when calcium levels are low?

Answer 38

They cause calcium release from the bones | This leads to bone disease brittle bone disease

Question 39

If secondary hyperparathyroidism isn't treated, what can happen?

Answer 39

The parathyroid hormones become autonomous and no longer respond to drugs that try and correct things This is tertiary hyperparathyroidism

Question 40

What can tertiary hyperparathyroidism lead to?

Answer 40

Fibrosis in the bone marrow This means red blood cells aren't produced Patients become anaemic and DO NOT respond to Epo

Question 41

What are the 3 stages involved in chronic kidney disease?

Answer 41

1. decreased activation of vitamin D 2. decreased calcium level 3. this stimulates secretion of parathyroid hormone

Question 42

What happens once parathyroid hormone begins to be secreted?

Answer 42

1. calcium is released from bones | 2. this leads to bone disease and renal osteodystrophy

Question 43

How are the kidneys involved in blood pressure control?

Answer 43

They secrete renin This converts angiotensinogen to angiotensin I

Question 44

What is blood pressure like in patients with kidney disease?

Answer 44

They often have high blood pressure It is a cycle - as high blood pressure causes kidney disease

Question 45

What blood tests are used to assess kidney function?

Answer 45

Urea and electrolytes 1. sodium 2. potassium 3. urea 4. creatinine Also bicarbonate and chloride levels

Question 46

What are normal Na+ levels?

Answer 46

133 - 146 mmol/L

Question 47

What are normal K+ levels?

Answer 47

3.5 - 5.3 mmol/L

Question 48

What are normal urea levels?

Answer 48

2.5 - 7.5 mmol/L

Question 49

What are normal creatinine levels?

Answer 49

Male: 64 - 104 micromol/L Female: 60 - 93 micromol/L

Question 50

What are normal bicarbonate levels?

Answer 50

22 - 29 mmol/L

Question 51

What are normal Cl- levels?

Answer 51

95 - 108 mmol/L

Question 52

What aspects are looked at when performing a urinalysis test for kidney function?

Answer 52

1. pH 2. haematuria (blood) 3. proteinuria (protein) 3. glucose (diabetes) 4. nitrites (infection) 5. leucocytes (infection)

Question 53

What do nitrites and leucocytes in the urine indicate?

Answer 53

Urinary tract infection Must take urine cultures to identify the organism before prescribing antibiotics

Question 54

What urine tests (other than urinalysis) are performed when looking at kidney function?

Answer 54

1. protein/creatinine ratio 2. albumin/creatinine ratio 3. midstream urine

Question 55

What is a normal protein/creatinine ratio?

Answer 55

Normal < 13.0

Question 56

What is a normal albumin/creatinine ratio?

Answer 56

Normal < 3.0

Question 57

What is midstream urine and when is it used?

Answer 57

It is a clean catch of urine It is sent off if a urinary tract infection is suspected

Question 58

What radiological investigations may be performed? What are you looking for?

Answer 58

Ultrasound is performed You want to look at the size of the kidneys and whether there is an obstruction

Question 59

What will the ultrasound look like for a patient with chronic kidney disease?

Answer 59

The kidneys will be small and shrunken due to fibrosis Normal kidneys are around 10-12 cm

Question 60

What is a MRA?

Answer 60

Magnetic resonance angiography

Question 61

Why is a kidney biopsy performed? How is it performed?

Answer 61

It is required to diagnose some rarer forms of kidney disease It is performed with ultrasound guidance

Question 62

What are the complications associated with kidney biopsy?

Answer 62

It is not performed in every patient due to the risks: Risk of bleeding - 1 in 100 Risk of losing a kidney - 1 in 1000