Chronic Kidney Disease

What is Chronic Kidney Disease?

Chronic kidney disease is characterized by impaired kidney function, reduced glomerular filtration rate, and protein in the urine (proteinuria).  The most common causes include hypertension (high blood pressure) and diabetes.  Other conditions such as systemic lupus erythematosus, scleroderma, infections (e.g., HIV, hepatitis C), and certain medications (e.g., NSAIDS) can also be responsible for the condition.

Patients with mild disease may be asymptomatic, but patients with end-stage renal disease require dialysis and have a high rate of morbidity and mortality.

What Causes Chronic Kidney Disease?

Chronic kidney disease is most commonly caused by hypertension (high blood pressure) and diabetes mellitus types I and II.  Other potential causes of the disease include:

• Polycystic kidney disease
• Renovascular disease
• Systemic lupus erythematosus
• Scleroderma
• Infections (e.g., HIV, hepatitis C, Streptococcus pyogenes)
• Certain medications (e.g., NSAIDS)

How Common is Chronic Kidney Disease?

Chronic kidney disease is exceedingly common in the United States and responsible for frequent primary care visits.  The most common causes include hypertension and diabetes mellitus.  Advanced cases typically require referral to a nephrology specialist to plan for dialysis access and consider renal transplantation.

Approximately 14% of people in the United States have chronic kidney disease.  About 660,000 Americans have a diagnosis of renal failure.

Signs and Symptoms

Patients with mild chronic kidney disease may be asymptomatic.  Individuals with more severe disease may develops symptoms and signs such as elevated blood pressure, swelling in the legs, fatigue, anemia, and itching of the skin.

Complications include:

• Anemia
• Vitamin D deficiency
• Electrolyte abnormalities – hyperkalemia, hypocalcemia, hyperphosphatemia
• Fluid disturbances – volume overload, lower extremity edema
• Hypertension
• Increased risk for infection
• Increased cardiovascular risk

Diagnosis

Chronic kidney disease is characterized by elevated creatinine, reduced glomerular filtration rate (GFR), and protein in the urine (proteinuria).  The diagnosis of chronic kidney disease is typically confirmed with blood tests including a CMP (comprehensive metabolic panel), phosphorus, CBC (complete blood cell count), 25-hydroxy vitamin D, parathyroid hormone (PTH), thyroid function (TSH, free T4), and urinalysis.  Your doctor will also usually check your cholesterol levels and screen for diabetes.  Infectious serologies for hepatitis B and C, as well as HIV are often obtained.

They will also likely order a spot urine microalbumin/total protein study.  They may also recommend a 24-hour urine protein collection.

An ultrasound of the kidneys is typically obtained to evaluate for polycystic kidney disease or any other structural abnormalities.

Some doctors will obtain an EKG (electrocardiogram) and ultrasound of the heart (echocardiogram) if they are concerned for heart disease.

Chronic Kidney Disease Treatment

Chronic kidney disease is treated via multiple approaches.  One of the first considerations is discontinuation of nephrotoxic medications (e.g., NSAIDs).  It is also important to treat the underlying etiology of kidney diseases such as hypertension and diabetes.

Blood pressure control is of chief importance – most patients will benefit from angiotensin converting enzyme - inhibitors (ACEI) such as Lotensin (benazepril), Vasotec (enalapril), or Zestril (lisinopril).  The goal blood pressure in patients with chronic kidney disease and diabetes is <140/90 mmHg.  Other antihypertensive agents may include:

• Diuretics (e.g., Hydrodiuril (hydrochlorothiazide), Lasix (furosemide))
• Angiotensin receptor blockers (e.g., Cozaar (losartan), Diovan (valsartan))
• Calcium channel blockers (e.g., Norvasc (amlodipine), Adalat (nifedipine))
• Beta blockers (e.g., Toprol (metoprolol), Coreg (carvedilol))

Fluid overload and edema also benefit from diuretic therapy.  Patients with diabetes should have their blood glucose levels optimized.  They may require referral to an endocrinology specialist.

Anemic patients should receive iron studies (ferritin, iron sat, total iron binding capacity) and other tests to work up anemia.  Patients with hemoglobin concentrations <10 g/dL may require the use of erythropoietin.

Patients with hypocalcemia often require calcium and vitamin D supplementation.  Hyperphosphatemia may require treatment with phosphate binders such as Renagel (sevelemer), Fosrenol (lanthanum carbonate), or PhosLo (calcium acetate).

Electrolyte abnormalities such as hyperkalemia may require low potassium diets, the use of loop diuretics (Lasix), and dose reduction or discontinuation of ACEIs or ARBs.  Severe cases of hyperkalemia are medical emergencies and typically require calcium gluconate, insulin, bicarbonate, Proventil (albuterol), intravenous Lasix, and Kayexalate (sodium polystyrene),

Features of this disease that is unresponsive to medical therapy require dialysis.  This is typically performed through an arteriovenous fistula placed in the upper extremity.  Sessions last typically 3 hours and patients usually go 3 days a week.  Some patients perform daily peritoneal dialysis.

Patients that meet certain criteria may be candidates for kidney transplant.