• Classification of the type of kidney disease is based on pathology, etiology and clinical history
  
• The most common causes of chronic kidney disease include:
  1. Diabetic glomerulosclerosis (33%)
  2. Vascular diseases (hypertension, renal artery stenosis) (21%)
  3. Glomerular diseases (primary or secondary) (19%)

A more detailed classification of chronic kidney disease is provided here

("Classification of Chronic Kidney Disease by Pathology, Etiology, and Prevalence in Patients with End-Stage Renal Disease")

2. Individuals at Increased Risk of Chronic Kidney Disease

• Some individuals without kidney damage, and with normal or elevated GFR, are at increased risk for development of chronic kidney disease, based on certain clinical and sociodemographic characteristics
  
• The following clinical and sociodemographic factors should be considered in determining an individuals risk of chronic kidney disease: 

  ("Potential Risk Factors for Susceptibility to and Initiation of Chronic Kidney Disease")

• Individuals at increased risk of developing chronic kidney disease should have measurement of urinary albumin-creatinine ratio (in a random untimed specimen) to test for kidney damage, and a serum creatinine to estimate the level of GFR

• Chronic kidney disease is usually silent. Therefore, clinical assessment relies heavily on history, laboratory evaluation and diagnostic imaging.
  
• Clues to the diagnosis of chronic kidney disease can be obtained from the patient's history

  ("Clues to the Diagnosis of Chronic Kidney Disease from the Patient's History")

• Further evaluation varies slightly, depending on whether chronic kidney disease is already established, or persons are at increased risk for chronic kidney disease:

4. When to Refer to a Nephrologist

1. Frequently the General Practitioner will make the diagnosis of chronic kidney disease

2. An urgent referral to a nephrologist is required for patients with:

   1. Rapid deterioration in kidney function over weeks to months, as determined by serial estimates of GFR

    2. GFR < 15 mL/min/1.73m2

In patients with stable chronic kidney disease, referral to a nephrologist should occur at a GFR < 30 mL/min/1.73 m2