The chemical pathology of renal disease

Question 1

What are the four main homeostatic and three main endocrine functions of the kidney?

Answer 1

Homeostatic:
-Waste products of metabolism
-Fluid and salt balance
-Acid base balance
-Removal of drugs
Endocrine:
-Epo production
-Renin aldosterone angiotensin system
-Hydroxylation of vitamin D

Question 2

What are the serum creatinine levels compared to baseline in the different stages of acute kidney injury?

Answer 2

Stage 1 - 1.5 to 1.9x baseline
Stage 2 - 2.0 to 2.9x baseline
Stage 3 - 3.0 or above

Question 3

What are the main causes of pre renal AKI?

Answer 3

Hypovolaemia - haemorrhage or dehydration
Renal artery stenosis
Sepsis and vasodilation
Pump failure

Question 4

What are the main causes of intrinsic AKI?

Answer 4

Ischaemia
Nephrotoxic drugs
Pyleonephritis
Early CKD, such as glomerulonephritis
Trauma

Question 5

What are the main causes of post renal AKI?

Answer 5

Obstruction such as stones or tumour

Question 6

What are the urine output findings in pre renal vs intrinsic AKI?

Answer 6

Pre renal - low

Intrinsic - initially high

Question 7

What is the urine:plasma osmolality findings in pre renal vs intrinsic AKI?

Answer 7

Pre renal - >2:1

Intrinsic - <1:1

Question 8

What is the urine Na in pre renal vs intrinsic AKI?

Answer 8

Pre renal - <15

intrinsic - >40

Question 9

What is the plasma sodium in pre renal vs intrinsic AKI?

Answer 9

Pre renal - high

Intrinsic - low

Question 10

What is the urea v creatinine in pre renal vs intrinsic AKI?

Answer 10

Pre renal - urea&raquo_space; creatinine

Intrinsic - urea = creatinine

Question 11

How do you treat pre renal vs intrinsic AKI?

Answer 11

Pre renal give fluids to increase kidney perfusion

Intrinsic if you give fluids you can kill the patient

Question 12

What are the earliest changes that occur in AKI and are potentially life threatening?

Answer 12

Metabolic acidosis as acid wastes not being excreted

Hyperkalaemia due to potassium not being excreted - life threatening above 8mmol/L

Question 13

What are the clinical features of AKI?

Answer 13

They are non specific and occur late on
As nitrogenous waste products built up you get: nausea, malasie, confusion
Can get fluid overload as less blood is filtered

Question 14

How is intrinsic AKI treated?

Answer 14

With dialysis to support renal function until the kidney has healed

Question 15

What is the treatment for post renal AKI?

Answer 15

Removal of the obstruction

Question 16

What are some of the main causes of CKD?

Answer 16

Diabetes
Hypertension
polycycstic kidneys
recurrent pyelonephritis
reflux nephropathy
glomerulonephritis

Question 17

What are the stages of CKD?

Answer 17

In eGFR ml/min
1 - >90
2 - 60-90
3 - 30-60
4 - 15-30
5 - <15

Question 18

What are some of the consequences of stage 3 CKD and above?

Answer 18

Hypertension due to water retention
Low calcium due to vitamin D, causes anaemia and anorexia
Get salt and water retention, acidosis and hyperkalaemia

Question 19

What endocrine changes occur at stage 3 and above CKD?

Answer 19

Patients will have to take 1,25 OH vitamin D due to decreased hydroxylation, this leads to low calcium levels and hyperparathyroidism.
Increased parathyroid hormone can cause osteomalacia (soft bones) from increased calcium reabsorption.
Epo production can drop and cause anaemia

Question 20

How is CKD managed?

Answer 20

Endocrine and metabolic abnormalities can be corrected with hormone replacement. Phosphate binders are given to prevent calcification. diet is modified to reduce potassium.
Acid - base balance corrected with bicarb
Dialysis for renal replacement

Question 21

What is renal glycouria?

Answer 21

Lack of uptake of glucose

Question 22

What is hypophosphataemic rickets?

Answer 22

Caused by decreased phophate uptake

Question 23

What are the three main forms of renal tubular acidosis?

Answer 23

Type 1 - (distal) failure to secrete H+ ions and excess K+ being lost, this causes hypokalaemia acidosis and kidney stones. Treated with bicarbonate and K+
Type 2 - (proximal) leads to alkalosis due to bicarbonate leak.
Type IV - Low renin and aldosterone - Causes hyperkalaemia