Renal disorders Flashcards
How much blood do the kidneys filter per day?
180L
How much urine do the kidneys create per day in the process of blood filtration?
~2L
What are the three functions of the kidneys?
- Filtration of blood and excretion of waste products
- Homeostasis (concentration of various substances in the blood)
- Endocrine (to maintain homeostasis)
List four metabolic wastes excreted by the kidneys and their sources
- Urea — metabolism of proteins
- Uric acids — metabolism of nucleic acids
- Creatinine — metabolism of muscle
- Bilirubin — breakdown of haemoglobin
How many nephrons are in each kidney?
~1 million
What is the function of the glomerulus?
High pressure filtration of water, salt, and other substances out of the blood
What is the glomerular filtration rate (GFR)? What is the normal rate?
How fast the glomeruli filter blood; normally 100-120mL/min
What tests can be used to estimate GFR?
- Creatinine level — it is proportional to GFR
- Inulin clearance (standard) — it is filtered but not secreted
What can skew a creatinine level test when trying to estimate GFR?
Muscular people have more creatinine
What is the maximal and minimal urine output?
Maximal: ~500mL/hour
Minimal: ~500mL/day
Which hormone is secreted from the adrenal gland to increase BP?
Aldosterone
Which hormone is secreted from the pituitary to increase BP?
Antiduiretic hormone (ADH/vasopressin)
What is the function of ADH?
Directs the distal tubules to retain more water in response to hydration state
What is acute kidney injury (previously called acute renal failure)?
Abrupt loss of kidney function within 7 days
List four causes of AKI
- Ischaemia
- Oxidising chemicals (e.g. paraquat)
- Obstruction
- Dehydration
What are the four sources of renal damage?
- Pre-renal (conditions above kidneys, e.g. CVD)
- Vascular
- Intrinsic (within kidneys)
- Obstructive (post-renal)
- Cardiorenal syndrome — linked system complications
Acute kidney can lead to what two life-threatening conditions?
- Metabolic acidosis — kidneys fail to remove H+ (acid)
- Hyperkalaemia — kidneys no longer regulate K+
AKI can lead to what two complications?
- Uraemia
- Altered fluid balance (HTN, oedema)
List the symptoms of AKI
- Urea and other nitrogen-containing substances in blood
- Fatigue
- Loss of appetite
- Headache
- N + V
- Hyperkalaemia
- Fluid imbalance
- Flank pain
What signs are used to dx AKI?
- Decrease in urine output OR large volumes of pale urine
- Blood tests: urea and creatinine
- Can take 24 hours before levels rise significantly
Describe the hospital rx for AKI
- Depends on underlying cause:
- Hypotensive — fluid, inotropes, vasoconstrictive drugs
- Hypertensive — diuretics
- Toxins — antidotes
- Obstruction — removal
- Kidney transplant/removal
What distinguishes diabetes insipidus from diabetes mellitus?
No glucose in urine