Stages of chronic kidney disease

Although chronic kidney disease is a progressive disease the good news is that not everyone will go on to develop kidney failure. Dr Louise Johnson explains the stages and why screening is imperative for people with diabetes.

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Chronic kidney disease (CKD) is a term that includes all degrees of decreased kidney function from at risk to mild, moderate and severe kidney failure.

Almost half of patients with CKD are older than 70 years of age. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines established the diagnosis of CKD as:

Either kidney damage or a decreased glomerular filtration rate (GFR) of less than 60ml/min/1.73m2 for at least three months.

The different stages form a continuum and are classified as:

• Stage 1 – Kidney damage with normal or increased estimated GFR (>90ml/min).
• Stage 2 – Mild reduction in GFR (60 – 89ml/min).
• Stage 3a – Moderate reduction in GFR (45 – 59ml/min).
• Stage 3b – Moderate reduction in GFR (30 – 44ml/min).
• Stage 4 – Severe reduction in GFR (15 – 29ml/min).
• Stage 5 – Kidney failure GFR < 15ml/min.

Markers

By itself measurement of estimated GFR may not be sufficient to identify Stage 1 and Stage 2 CKD. In these patients, the estimated GFR may be normal or near normal. In such cases, the presence of one or more of the following markers of kidney damage can establish the diagnosis:

• Albuminuria (albumin excretion in the kidneys >30mg/24 or Albumin: creatinine ratio > 30mg/g)
• Urine sediment abnormalities
• Electrolyte disorders
• Structural kidney abnormalities as seen by imaging
• History of kidney transplant

Two important tests

1. Urine Albumin-to- Creatinine ratio (UACR)

This is a test of the urine to assess the relationship between albumin (which is a protein that shouldn’t be in urine) and creatinine. If protein leaks into the urine, it’s a sign of kidney damage.

UACR levels are staged as:

• A1 – lower than 3mg/mmol
• A2 – 3 to 30mg/mmol – moderate increase
• A3 – higher than 30mg/mmol – severe increase

2. Estimated Glomerular Filtration Rate (eGFR)

This is a blood test that shows how well your kidneys filter your blood per minute. A GFR of 100 is normal.

Stage 1 kidney disease

In Stage 1, there is mild damage to the kidneys. They are quite adaptable for this, allowing them to keep performing at 90% or better. At this stage, CKD is likely to be discovered by chance during routine blood analysis. Usually in people with diabetes or hypertension (these are the two main causes of CKD).

Symptoms

None

Treatment

Manage all risk factors:

• Keep blood glucose in normal range or HbA1c below 7%.
• Keep blood pressure below 130/80 mmHg.
• Don’t smoke.
• Sleep seven to eight hours per day.
• Exercise 30 minutes five times a week
• Reduce stress and anxiety.
• Maintain a healthy weight.

Stage 2 kidney disease

In Stage 2, the kidney function is between 60 and 89%.

Symptoms

Usually, asymptomatic

Treatment

Manage risk factors as in Stage 1.

Stage 3 kidney disease

Stage 3a is when your kidney function is 45 to 59%.

Stage 3b is when your kidney function is 30 to 44%

The kidneys aren’t filtering waste, toxins and fluids as well as it should, and toxin and fluid build-up begin to manifest.

This is usually the first time when people with CKD are diagnosed.

Symptoms

Not all people are symptomatic yet, but you can have these symptoms:

• Back pain
• Fatigue
• Loss of appetite
• Persistent itching
• Sleep problems
• Swelling of hand and feet
• Urinating more or less
• Weakness

Treatment

Dietitians may help to prescribe a diet that is low in sodium, phosphate, potassium and protein to protect the kidneys.

Medication that reduce symptoms and preserve kidney function:

1. Angiotensin-converting enzyme (ACE) inhibitor.
2. Sodium glucose cotransport 2 (SGLT2) inhibitors. In SA, there are two drugs in this class dapagliflozin and empagliflozin. This class showed in specific studies with patients with and without diabetes an improvement in kidney function on this drug.
3. Diuretic for fluid retention.
4. Cholesterol lowering drug. This is important since the risk of ischemic heart disease and stroke increases in this stage. Important to stop taking certain pain killers called non-steroidal anti-inflammatory drugs (NSAIDS).

Stage 4 kidney disease

This stage has moderate to severe kidney damage. The kidneys function between 15 and 29%. According to the Centre for Disease Control and Prevention (CDC), 40% of people with severe reduced kidney function aren’t aware they have it.

Symptoms

• Back pain
• Decreased mental sharpness.
• Fatigue
• Loss of appetite
• Muscle cramps and twitches
• Nausea and vomiting
• Persistent itching
• Shortness of breath
• Sleep problems
• Swelling of hand and feet
• Weakness
• Weight loss

This stage is also at high risk for heart disease and stroke.

Treatment

The same as Stage 3. In Stage 4, it’s important to be part of a health team to monitor you closely regarding electrolytes, medication, diet as well as possible complications, such as anaemia, bone loss and hypertension.

In Stage 4, erythropoietin supplement for anaemia is important.

Stage 5 kidney disease

This stage means your kidney function is less than15% or you have kidney failure.

Symptoms

The symptoms are the same as Stage 4, but the intensity is worse. A significant drop in kidney function puts more stress on the heart, increasing the risk of heart disease and stroke.

Once you have Stage 5 kidney failure, life expectancy is a lot shorter without dialysis or a kidney transplant.

Dialysis isn’t a cure for CKD but a process to remove fluid and toxins.

Although CKD is a progressive disease, not everyone will go on to develop kidney failure. Symptoms of early kidney disease are mild or even absent. It’s important to screen for kidney disease if you have risk factors such as diabetes and hypertension. Always join a healthcare team to help you along this journey.

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