renal Flashcards
what are the main roles of the kidneys?
- Regulate water and electrolyte content in the
body (e.g. Sodium, Potassium) - Retention of substances needed by the body
–Glucose, Protein - Maintain acid/base balance
- Key role in regulating blood pressure
- Excrete waste products (e.g. urea, creatinine),
water soluble toxic substances
and drugs - Endocrine functions
how is urea produced?
Produced when protein or a.a’sare broken down in
the liver. Urea is normally cleared by glomerular
filtration and reabsorbed in the kidney tubules.
what causes an increase in urea?
dehydration
concurrent infection
gastric blood loss
what causes a decrease in urea?
oedema
low protein diet
decrease liver function
pregnancy
chronic nutritional status
what is the reference range for urea?
3.0-6.5mmol/L
how is creatine produced?
Produced continuously in muscle and is a function
of muscle mass
waste product of muscle metabolism
how is creatine predominantly cleared?
Predominantly cleared from the body via glomerular
filtration
why is creatine often used to determine kidney function?
Plasma concentration of creatinine linked to both
muscle mass and the kidneys ability to excrete
creatinine
what factors affect renal function?
gender
age
weight
race
muscle mass
what equation is used to calculate crcl?
cockcroft- gault
F x (140 –age) x weight (Kg)//
Serum Creatinine (μmol/L)
what is the eGFR?
modified diet in renal disease
what ways can you estimate renal function?
- Cockcroft and Gault equation
- Modified Diet in renal disease
- EPI-CKD
- 24 hour urine output
what calculation should you use to check renal clearance if the patient is on a narrow therapeutic index drug?
For narrow therapeutic index drugs, use eGFR –
However correct for patients actual BSA
eGFR x Actual BSA//
1.73
OR If in doubt, and narrow therapeutic index drugs
calculate CrCl via Cockcroft and Gault equation
whats the most important thing when interrpting results?
you need to know the patients baseline
you cannot determine it on one result
what are the different ways in which an AKI presents?
AKI: No previous CKD, patient recovers or
continues with degree of CKD
* Acute on chronic: Unknown CKD presents with
AKI
* Routine appointment finds an increase in
creatinine and refers to nephrology clinic
what is AKI ( acute renal failure- old name)
‘The abrupt transition from functioning
kidneys to kidney function which is unable to
accomplish biochemical homeostasis‘
how is AKI defined?
- Serum creatinine rises by ≥ 26μmol/L within 48
hours or - Serum creatinine rises ≥ 1.5 fold from the reference value, which is known or presumed to have occurred within one week or
- urine output is < 0.5ml/kg/hr for >6 consecutive
hours
what are the criteria for stage 1 AKI?
SCr- increase> 26umol/L within 48 hours or increase> 1.5 to 1.9x reference SCr
and <0.5ml/kg/hr for>6 consecutive hours