Getting Started: Elevated Serum Creatinine

1 ApproachCLINICALNeil Finkle, MD, FRCPCP resented at the 78th Annual Dalhousie Refresher Course, 2004 Getting started : Elevated Serum CreatinineSome 810 Canadian patients/million population requiredrenal replacement therapy (dialysis and transplant) projected increase in annual incidence rate is %.2 Creatinine can be Elevated in several conditions (Table 1). Acuterenal insufficiency (ARI) is defined as a rise in Serum creatinineover a period of days to weeks. ARI is a medical emergency andrequires urgent assessment by a nephrologist or other qualified specialist.

2 Chronic renal insufficiency (CRI), also known as chron-ic kidney disease (CKD), demonstrates a rise in Serum creatinineover a period of months to years. Are there special recommendations forthose at highest risk?Patients at risk (Table 2) should have periodic assessment oftheir renal function. The Creatinine clearance (CrCl) is a rea-sonable estimate of the glomerular filtration rate (GFR), thestandard measure of renal function. The CrCl can be measuredThe Canadian Journal of CME / January 2005 69 Stanley s StruggleStanley, 56, presents to his general practitionerfor evaluation of right flank pain.

3 His is chronicand progressive, with three associated episodesof gross hematuria in the past two years. Hehas had hypertension treated with a more on Stanley, go to page 2 Who is most at risk? Hypertensive patients (risk directly related to magnitude of blood pressure elevation) Diabetes patients Advanced age Patients with atherosclerosis Patients with family history of kidney disease Common in patients with a history of congestive heart failure and/or myocardial infarction Patients of lower educational levels Those using non-steroidal anti-inflammatory drugs Smoking is becoming a recognized risk factor.

4 Especially among patients who have smoked heavilyfor long periods of timeTable 1 Common causes of CKD Diabetic nephropathy Hypertensive nephrosclerosis Ischemic nephropathy Chronic glomerulonephritis Chronic intestitial nephritis Cystic renal diseasedirectly using a 24-hour urine collection for Creatinine orestimated using the Cockcroft-Gault formula (Table 3).What is the initial workup?The initial workup should include: electrolytes: useful in assessing acid-base balance andidentifying hyperkalemia; urea; Creatinine (current and previous): to gauge the acuityof the process; calcium, phosphorus and albumin: calcium and albumin rule out hypercalcemia as a cause of RI(hypoalbuminemia can also be a feature of thenephrotic syndrome); urinalysis.

5 And renal ultrasound: important to evaluate renal mass andcharacter, and to look for obstructive certain circumstances the following investiga-tions may be indicated: urine protein-to- Creatinine ratio, 24-hour urine for protein and Serum protein about early referral?There is mounting evidence that the diseases causing CKDcan be positively impacted. Substantive blood pressurecontrol and the introduction of angiotensin-convertingenzymes (ACE) inhibitors and angtiontensin receptor blockersApproachCLINICALDr.

6 Finkle is a lecturer, faculty of medicine,Dalhousie University, and attending staff, Capital District HealthAuthority, Halifax, Nova ScotiaEvaluating StanleyElectrolytes: NormalUrea: 12 mmol/LCreatinine: 145 mmol/L (105 in 1998)Urinalysis: 1 g/L protein, 1+ blood, no glucose or white bloodcell (WBC)Renal ultrasound: Bilateral renal enlargement with numerouscortical cystsNo hydronephrosis or stonesFor Stanley s diagnosis, go to page 3 Stages of CKD Stage 1 Kidney damage with normal GFR CrCl* > 90 Stage 2 Mild CrCl 60-89**Stage 3 Moderate CrCl 30-59 Stage 4 Severe CrCl 15-29 Stage 3 End-stage renal failure CrCl < 15 or dialysis*CrCl = Creatinine clearance ( )2 CrCl measure/estimated by Cockcrof-Gault Formula.

7 ((140-age) x weight in kg) / Serum Creatinine = CrCl in ml/min(multiply by for males)**May be normal for ageTable adapted from K/DOQI Clinical Practice Guidelines for ChronicRenal Disease. Am J Kidney Dis, 2002; 39(2, Suppl1) Canadian Journal of CME / January 2005(ARBs) has altered the natural history of proteinuric and some non-proteinuric renal disease alike. The complications that manifest inCKD can most effectively be managed with the input of a renal spe-cialist. Early referral yields improved health-care outcomes and isexpected to lower health-care costs (Table 4).

8 This is effected byidentifying those with reversible RI early on, and employing strate-gies that will delay the rate of progression of referred late to a nephrologist are more likely to havehypoalbuminemia and anemia, are later at starting dialysis and aremuch less likely to have a functioning permanent vascular accessfor the first referred late to dialysis have a lower rate of , earlier referral is associated with improved patient sur-vival and stabilization of renal Canadian Organ Replacement Register, Canadian Institute for Health Information.

9 CORRP reliminary Report For Dialysis and Transplantation 2002. Ottawa: The Register; Schaubel DE, Morrison HI, Desmeules M, et al: End-stage renal disease in Canada:Prevalence projections to 2005. CMAJ 1999; 160(11) references available contact The Canadian Journal of CMEat s SummaryStanley is diagnosed with autosomal dominant polycystickidney disease (PKD). He is referred to a nephrologist therapy is prescribed for the flank pain. His bloodpressure is brought down to target (130/80 mmHg) with theaddition of an angiotensin-converting enzyme inhibitor and a no-added-salt diet.

10 Stanley receives education about his disease and the futureimplications thereof. He is asked to avoid non-steroidal anti-inflammatory drugs. His children are screened for PKD. Table 4 Who should you refer? Patients with a repeatedly elevatedserum Creatinine or reduced Creatinine clearance should be considered for nephrologic evaluation. All patients with a newly discovered renal insufficiency (RI)need to undergo investigations to evaluate for potentially reversiblecauses. Patients with stable mild to moderate chronic kidney disease(CKD) may be seen electively,whereas patients with a rapidly rising Creatinine ( 20% rise increatinine over weeks to months)or with severe CKD should be seenmore urgently.