Creatinine = Non-protein end product of creatinine metabolism. Formed from skeletal muscle and excreted in constant amounts. Completely filtered by kidney (marker of GFR). Production proportional to muscle mass
- Relatively unaffected by diet, exercise or urine volume
- More sensitive test of renal damage. Elevation of levels almost exclusively secondary to renal impairment
- Clearance is an excellent indicator of kidney efficiency in clearing creatinine
- Clearance levels become abnormal when >50% of nephron units have become damaged
Causes of increased serum creatinine
- Renal impairment (>50% nephrons affected) – any cause of renal failure, basically
- Decreased perfusion to the kidney
- Dehydration, hypovolaemia, shock
- Intrinsic renal lesion
- Nephrotoxic drugs
- Post renal obstruction
- Nephrotoxic drugs
- NSAID, aspirin, indomethacin
- Ampicillin, rifampicin, cephalosporin, aminoglycosides
- Frusemide, Thiazides, acetazolamide, mannitol
- Lithium, iron, lead, copper, gold
- Very large muscle mass (athletes) (without renal compromise)
- NOT affected by dietary protein intake
- Interfere with colorimetric analysis (Glucose, fructose, ascorbic acid)
Causes of a Decreased Creatinine
- Conditions characterised by muscle wasting
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.