Normal functions of the kidneys Flashcards
What are the 5 functions of the kidneys?
SwwABED
Excretion of salt, water, and waste products of metabolism Regulate acid - base Regulate BP Produce erythropoetin, activates Vit D Excrete drugs / metabolites
How do we measure excretory renal function?
1) PLASMA / SERUM CREATININE - but this is related to muscle mass. It may not be elevated above normal range until 50% GFR lost.
2) ESTIMATED GFR :MDRD FORMULA
3) CREATININE CLEARANCE
4) ISOTOPE GFR
How does serum creatinine (Scr) relate to GFR?
If Scr is high but eGFR is low then kidney failure
If Scr high because of high muscle then need high eGFR too
What is normal rate of eGFR?
60 - 100 but only need 10 to live so large reserve
What is creatinine?
A waste product of muscle metabolism. It will increase or decrease depending on the efficiency of the kidney
What does protein in the urine indicate?
Leakage of kidney filters - glomerula disease
What are the two types of renal failure?
Acute and chronic:
Acute kidney injury (AKI)
Chronic kidney disease (CKD)
What is AKI?
Acute kidney injury - a rapid loss of renal excretory function. Implies reversibility if underlying condition is treated
What is CKD?
Chronic kidney disease - slow progressive loss of excretory renal function. Cause often unknown, usually irreversible and so management is aimed at slowing the progression
What are the causes of pre renal AKI? (before the kidney)
Salt and water loss (diarrhoea/vomit/diuretics)
Haemorrhage
Hypotension
Renovascular disease
What are the causes of renal AKI?
Tubular necrosis
Interstitial nephritis
Acute glomerulonephritis
What are the toxic substances that cause AKI?
Antibiotics Radiographic contrast media Chemo agents Rhabdomyolysis Intravascular haemolysis Tumour lysis Solvents Hepatorenal syndrome
What is a hepatonephrotic kidney?
The collecting system dilates, increasing the pressure
Occurs from an obstruction of ureter or bladder
What are the causes of post renal AKI? (after the kidney)
Obstruction to outflow from one / both kidneys
What are the causes of CKD?
Diabetic nephropathy Genetic - polycystic kidney disease Vascular disease Chronic glomerulonephritis Chronic outflow urinary obstruction
How is CKD classified?
5 stages:
1 = normal kidney funtion with some other evidence of disease
5 = eGFR
What are the consequences of renal failure?
Accumulation of K+, urea, creatinine, H+, water,
Deficiency of erythropoetin (anaemia) and Vit D (hyperPTH)
Delayed drug excretion
What is renal replacement therapy?
erythropoetin VIt D sodium bicarbonate Dialysis and transplant (to clean blood) Anticoagulants - heparin, warfarin and aspirin
What are the general consequences of immunosuppression?
Infection
Viral transmission with transplant
Malignancy
What effects do cyclosporins have?
anti-rejection drug for transplants
nephrotoxicity
tremor
hirsuitism
gingival hypertrophy
What drug interactions involve cyclosporins?
Cyclosporins +: macrolides, diltiazem, enzyme inhibitors
