T3 L8: Measuring renal function Flashcards
What are the 7 types of people who are at risk of developing renal failure?
- extremes of age (neonates and elderly)
- Polypharmacy
- specific disease states
- when receiving long term analgesia (eg. NSAID)
- Transplant patients
- Drug therapy
- imaging procedures
What is analgesia?
Pain relieving drugs
What are some blood markers of renal function?
Plasma or serum creatine, plasma or serum urea or blood urine nitrogen
What is plasma creatinine increased by?
Large muscle mass, dietary intake, drugs, ketoacidosis, ethnicity
What is plasma creatinine decreased by?
Reduced muscle mass, cachexia, immobility, pregnancy, severe liver disease
What is creatinine a product of?
The breakdown of ATP in muscles
What is urea a product of?
The breakdown of proteins in the liver
What is blood urea nitrogen increased by?
High protein diet, hypercatabolic conditions like severe infection, gastrointestinal bleeding, muscle injury, drugs, Tetracycline, hypovolaemia
What is blood urea nitrogen decreased by?
Malnutrition, liver disease, sickle cell anaemia due to increased GFR, syndrome of inappropriate ADH (SIADH)
What is Inulin used for and why?
Used to measure renal clearance because its freely cleared but not reabsorbed or secreted in the body
Excretion rate= rate it was filtered
Why can electrolytes be used to measure renal clearance?
Because they are freely filtered and partly reabsorbed
Excretion rate= filtration rate - reabsorbed
Why can glucose and amino acids be used as a measure of renal clearance?
They are freely filtered but fully reabsorbed so there is not excretion
Why can PAH (para-aminohippuric acid) be used as a measure of renal clearance?
It’s freely filtered but not reabsorbed and fully secreted
What is GFR a measure of?
The rate at which filtrate is produced in the kidneys
Why is inulin not often used clinically?
It has to be administered by IV, chemical analysis of it is technically demanding
