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Special Focus: Chronic Kidney Disease

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From the October ACP Observer, copyright 2007 by the American College of Physicians.

Currently, 387,000 patients in U.S. have end-stage renal disease (ESRD), but there are 100,000 new cases each year. The healthcare expenses for treatment were $17 billion in FY 2005. This will rise to an anticipated 600,000 cases, which could cost $28 billion by 2010.

Cross-section of a human kidney.


Cross-section of a human kidney.



The anticipated wave of chronic kidney disease (CKD) meets the definition of a public health threat. While the focus is on getting patients into dialysis and paying for it, internists and nephrologists can improve coordination of care and focus on prevention, said Thomas D. DuBose, FACP, FASN, a professor and chair of internal medicine at Wake Forest University School of Medicine.

There's a lesson to be learned from overseas. For example, U.S. and Norwegian incidence rates of CKD are comparable, but in the U.S. there is a three-fold risk for progression from stage 3 to stage 4 disease as compared to Norway. This may be due to the fact that Norway has more coordinated care, preventive strategies and surveillance by the country's primary care providers.

The following strategies for management of CKD are derived from PIER, and detailed evidence is available online.

PREVENTION AND SCREENING

Diabetes is the single largest cause of CKD in the U.S. and the cause of ESRD in 45% of patients starting dialysis.

  • Aim to prevent CKD by achieving glycemic control (hemoglobin A1c <7%) in diabetic patients using dietary interventions and medications. Achieve good blood pressure control (<140/90) in those with hypertension with lifestyle modification, antihypertensives and with specific renoprotective agents such as ACE inhibitors or ARBs.
  • In elderly patients, those with diabetes and hypertension and those in specific ethnic groups (African Americans, Hispanics, Asians and Native Americans), screen for CKD by checking blood pressure and obtaining an estimated GFR, a urinalysis to look for cells and a urine protein level.

DIAGNOSIS

The National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines available at www.kidney.org recommend a comprehensive approach to the diagnosis and evaluation of the patient with CKD.

  • Although early CKD is usually asymptomatic, ask the patient about urinary symptoms, symptoms of fluid overload, uremic symptoms, symptoms of disease that can cause CKD (including diabetes and hypertension) and medication history.
  • On physical examination, look for hypertension, signs of fluid overload, funduscopic signs of hypertension and/or diabetes, signs of uremia and signs of peripheral neuropathy and autonomic dysfunction.
  • Obtain additional tests to evaluate CKD, including a spot urine for protein and creatinine, urinalysis for red cells and white cells, CBC, electrolyte panel, lipid profile, ultrasound of the kidneys, and a cystatin C level in patients at risk for cardiovascular disease. Include a PTH level and serum albumin in patients with stage 3 CKD or higher.
  • Classify CKD further as diabetic kidney disease, non-diabetic kidney disease or kidney disease in a renal transplant.
  • Calculate estimated GFR using the MDRD or Cockcroft -Gault equation and determine the stage of CKD.
    MDRD equation: GFR (mL/min.1.73 m2) = 186 x (PCR) - 1.154 x (age) - 0.203 x (0.742 if female) x (1.210 if black)
    Cockcroft-Gault equation: creatinine clearance = (140 - age) x weight in kg/(72 x serum creatinine) x 0.85 (in women)
    Classify the stage of CKD using estimated GFR mL/min.1.73 m2:
    Greater than or equal to 90: stage 1
    60-89: stage 2
    30-59: stage 3
    15-29: stage 4
    <15: stage 5

THERAPY

Nondrug therapy

Because patients with CKD often have salt-sensitive hypertension, salt restriction is an important part of management. Other non-drug measures such as diet, exercise and weight loss are also helpful in lowering BP.

  • Restrict dietary sodium to <2.4 grams daily
  • Encourage regular exercise to maintain near ideal body weight.
  • Recommend a low protein, low phosphorus diet but be careful to maintain adequate nutrition.

Drug Therapy:

Medical therapy can delay progression of decline in renal function, as well as treat concomitant conditions such as high blood pressure, hyperglycemia, anemia, bone disease, neuropathy and malnutrition, and cardiovascular risk factors.

  • Control blood pressure to <130/80 with an ACE inhibitor or ARB in patients with diabetic kidney disease and in those with nondiabetic kidney disease and proteinuria; start with a diuretic in those with nondiabetic kidney disease and no proteinuria. Monitor blood pressure, potassium level and GFR after beginning therapy.
  • In patients with frank proteinuria, use ACE inhibitors or ARBs to maintain protein excretion between 500 and 1,000 mg/day and to prevent progression of nephropathy.
  • In patients with diabetes, use oral agents and/or insulin to maintain hemoglobin A1c levels <7%.
  • Treat anemia due to CKD with erythropoietin to maintain hemoglobin levels between 11-12 g/dL but not higher, and use oral or intravenous iron to maintain transferrin saturation above 20% and serum ferritin levels above 100 ng/mL.
  • Use phosphate binders in the form of calcium salts to lower elevated PTH level and to keep serum calcium and phosphorus levels in the normal range.
  • Use alkali therapy to maintain serum bicarbonate levels between 20 and 26 mEq/L.
  • Use dietary restriction of potassium and use sodium polystyrene sulfonate as needed to keep serum potassium levels within the normal range.
  • Note that use of gadolinium-based contrast agents in patients with renal disease has been associated with nephrogenic systemic fibrosis, also known as nephrogenic fibrosing dermopathy.

CONSULTATION AND HOSPITALIZATION

Optimal management of patients with CKD will require active collaboration between the primary care physician and a nephrologist. With more than 10 million Americans estimated to have CKD, initial management of these patients will begin with the primary care physician. As renal function declines, however, early consultation with a nephrologist may help in slowing progression and, in those who progress, ensure smooth transition to ESRD.

  • Consider consulting a nephrologist for patients with proteinuria >3 to 3.5 g/24 hr, nephritic syndrome (hematuria, proteinuria, hypertension), estimated GFR decline of 50% from the previous measure over a 3-month period (or less) or type 2 diabetes and proteinuria without coexistent retinopathy. Be certain to do so when the GFR first falls below 30 ml/min to enable intensification of therapy to slow progression of disease and eventually prepare for renal replacement therapy.
  • Consult a urologist when obstructive uropathy is suspected and consult a surgical specialist when vascular access is required or transplantation is being considered.
  • Hospitalize patients for complications including hyperkalemia with ECG changes, intractable fluid overload, mental changes due to uremia, severe acidosis, pericarditis, acute renal failure or required surgical procedures.

PATIENT EDUCATION AND FOLLOW-UP

The success of CKD management strategies ultimately depends on patient self-management and his or her ability and willingness to change and maintain certain behaviors. Appropriate patient education through a predialysis program or group sessions can result in a systematic transition to ESRD, avoiding the need for temporary catheter placement and minimizing uremic symptoms and complications.

  • Encourage patient self-management and willingness to change and maintain certain behaviors, including diet and exercise, smoking cessation, limiting alcohol consumption, adherence to medication regimens, self-monitoring of BP and adherence to plans for medical follow-up.
  • Prepare those with advanced disease for eventual initiation of renal replacement therapy and the options available to them such as hemodialysis, including home hemodialysis and nocturnal dialysis, peritoneal dialysis and transplantation. Advise patients facing future hemodialysis about protecting their non-dominant arm for access placement.

The information included herein should never be used as a substitute for clinical judgment and does not represent an official position of ACP.

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