Increased Creatinine Concentration - Quick Reference

This is a Quick Reference article. See also the main article Increased blood creatinine concentration and renal function tests Increased Blood Creatinine Concentration, Egfr and Renal Function Tests.

Investigations and interpretation

Plasma creatinine concentration, estimated glomerular filtration rate (eGFR Gfr Calculator) and urinalysis are the principal renal function tests.
Large muscle mass may increase creatinine concentration.
No further investigations are needed if eGFR is over 60 ml/min, unless the patient has haematuria, proteinuria or diabetes with microalbuminuria.
GFR falls with advancing age (in an elderly person often 60-90 ml/min). In elderly patients, eGFR may be as low as 30-45 ml/min without it signifying progressive renal disease, unless there is also proteinuria, diabetes or hypertension.

Underlying causative conditions?
- Acute illness: epidemic nephropathy Epidemic Nephropathy, vasculitis Vasculitides
- Chronic disease: previous renal disease, hypertension, diabetes, atherosclerosis, prostatic hypertrophy, rheumatic disease, myeloma
- Medicine or other toxic factor (NSAIDs, ACE inhibitors, angiotensin receptor blockers, diuretics, contrast media, substances used as alcohol substitutes; trimethoprim may increase creatinine concentration without impairing renal function)
Physical examination
- General condition (dehydration and fever indicate an acute illness)
- Blood pressure (often elevated in renal disease), auscultation of the arteries
- Palpation of the abdomen (cystic kidneys, urinary retention)
- Rectal examination (enlarged prostate, measurement of residual urine if indicated Determining the Volume of Residual Urine by Ultrasonography)
- Oedema (nephrosis, low albumin)
Other investigations
- Chemical urine screen; urinary sediment and culture if indicated
- Albumin/creatinine ratio, and if this is abnormal, overnight collection for urinary albumin especially in diabetes, or 24-hour urine protein
- Plasma potassium, calcium, phosphate and albumin (if proteinuria > 3 g/24 h)
- Blood counts (anaemia, thrombocytopenia), CRP, ESR
- Ultrasound of the kidneys (size, parenchyma, hydronephrosis, cystic disorder)

Emergency referral
- Acute renal failure or systemic symptoms in addition to high creatinine Acute Kidney Injury (e.g. fever, symptoms affecting upper or lower respiratory tract or joints)
- Low urine output or anuria without a quickly rectifiable cause (obstruction, hypovolaemia)
Non-urgent referral
- Progressing disease discovered as an incidental finding (increasing creatinine/decreasing GFR) or if there are other signs of renal disease, e.g. proteinuria
There is no need to refer a patient with several comorbidities if renal disease plays no particular part in prognosis.