The chemical pathology of renal disease Flashcards
What are the four main homeostatic and three main endocrine functions of the kidney?
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
What are the serum creatinine levels compared to baseline in the different stages of acute kidney injury?
Stage 1 - 1.5 to 1.9x baseline
Stage 2 - 2.0 to 2.9x baseline
Stage 3 - 3.0 or above
What are the main causes of pre renal AKI?
Hypovolaemia - haemorrhage or dehydration
Renal artery stenosis
Sepsis and vasodilation
Pump failure
What are the main causes of intrinsic AKI?
Ischaemia Nephrotoxic drugs Pyleonephritis Early CKD, such as glomerulonephritis Trauma
What are the main causes of post renal AKI?
Obstruction such as stones or tumour
What are the urine output findings in pre renal vs intrinsic AKI?
Pre renal - low
Intrinsic - initially high
What is the urine:plasma osmolality findings in pre renal vs intrinsic AKI?
Pre renal - >2:1
Intrinsic - <1:1
What is the urine Na in pre renal vs intrinsic AKI?
Pre renal - <15
intrinsic - >40
What is the plasma sodium in pre renal vs intrinsic AKI?
Pre renal - high
Intrinsic - low
What is the urea v creatinine in pre renal vs intrinsic AKI?
Pre renal - urea»_space; creatinine
Intrinsic - urea = creatinine
How do you treat pre renal vs intrinsic AKI?
Pre renal give fluids to increase kidney perfusion
Intrinsic if you give fluids you can kill the patient
What are the earliest changes that occur in AKI and are potentially life threatening?
Metabolic acidosis as acid wastes not being excreted
Hyperkalaemia due to potassium not being excreted - life threatening above 8mmol/L
What are the clinical features of AKI?
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
How is intrinsic AKI treated?
With dialysis to support renal function until the kidney has healed
What is the treatment for post renal AKI?
Removal of the obstruction
What are some of the main causes of CKD?
Diabetes Hypertension polycycstic kidneys recurrent pyelonephritis reflux nephropathy glomerulonephritis
What are the stages of CKD?
In eGFR ml/min 1 - >90 2 - 60-90 3 - 30-60 4 - 15-30 5 - <15
What are some of the consequences of stage 3 CKD and above?
Hypertension due to water retention
Low calcium due to vitamin D, causes anaemia and anorexia
Get salt and water retention, acidosis and hyperkalaemia
What endocrine changes occur at stage 3 and above CKD?
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
How is CKD managed?
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
What is renal glycouria?
Lack of uptake of glucose
What is hypophosphataemic rickets?
Caused by decreased phophate uptake
What are the three main forms of renal tubular acidosis?
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
