What to know about stage 4 chronic kidney disease

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At stage 4 CKD, waste products can build up in the blood. This can lead to health issues throughout the body, including:

• heart disease
• anemia
• hypertension, also known as high blood pressure
• hyperphosphatemia, which is high phosphorus levels
• bone disease
• hyperkalemia, which is high potassium levels

A person may feel these effects in several ways, including:

• fatigue
• weakness
• nausea and vomiting
• edema, or swollen arms and legs due to fluid buildup
• muscle cramps
• changes in how often they urinate
• lower back pain
• appetite loss

Stage 4 CKD sets in over time when stage 3 CKD has progressed due to further kidney damage. High blood pressure and diabetes are the most frequent causes of CKD.

Diabetes

People with diabetes may have consistently high blood glucose levels due to the body not making enough insulin. Glucose is a type of sugar. Insulin is a hormone.

Insulin usually instructs cells to remove glucose from the blood. If the body does not have enough insulin, more glucose travels around the body in the blood, potentially damaging blood vessels and organs. This can damage the filters in the kidneys, reducing their ability to function as usual.

According to data collected between 2011 and 2014, 24.5% of people in the United States with diabetes had stages 3–4 CKD compared with 4.9% of people who did not have diabetes.

Hypertension

According to the National Institute of Diabetes and Digestive and Kidney Disorders, around 108 million people in the United States have high blood pressure. It is also the second most common cause of kidney failure, accounting for 26% of all cases.

High blood pressure can damage and narrow the kidneys’ veins and arteries. This can reduce their filtering abilities and lead to fluid buildup in the blood vessels. In turn, this can drive further rises in blood pressure in a harmful cycle that can worsen kidney damage.

Less common causes

Other conditions can cause CKD, including:

• glomerulonephritis, which accounts for CKD in 16% of people, and typically occurs from infection
• toxicity from drugs or overexposure to heavy metals
• systemic (full-body) diseases, such as lupus
• conditions in which immunoglobulin A (IgA) antibodies build up in different parts of the kidney and blood vessels, such as IgA glomerulonephritis and IgA vasculitis
• rare genetic disorders, such as Alport syndrome
• renal artery stenosis, which is the narrowing of the arteries in the kidneys

A doctor will take symptoms into account when diagnosing stage 4 CKD. They may request a range of tests to measure the extent of kidney damage and identify the possible causes.

According to the Centers for Disease Control and Prevention (CDC), around half of all people with extremely low kidney function who are not receiving dialysis treatment do not know they have CKD.

Measuring the stage

A doctor may request an estimated glomerular filtration rate (eGFR) test to check the severity of kidney function loss.

This blood test measures how much creatinine remains in the blood. Creatine is a waste product. Healthy kidneys filter this substance out of the body, but damaged kidneys cannot remove as much.

People with stage 4 CKD have an eGFR of 15–29. These lower eGFR numbers indicate more severe kidney damage.

A doctor may also test the urine for protein. Proteinuria, or too much protein in the urine, is a sign of stage 4 CKD.

Identifying the cause

Doctors may request or administer the following tests to determine what may be causing stage 4 CKD:

• other urine tests
• blood pressure measurements
• ultrasound, MRI, or CT scans to check the physical structure of the kidneys
• biopsy
• genetic testing, if a person may have a rare condition or if certain conditions run in a person’s family

Depending on the cause, a doctor can suggest which treatments and management methods could help prevent further kidney damage.

If a primary care physician identifies stage 4 CKD, they will refer the individual to a kidney specialist called a nephrologist.

This specialist cannot reverse kidney damage, but they can recommend treatments to slow disease progression. Treatment is vital to prevent CKD progression, as the next stage of CKD may involve kidney failure.

Medications for stage 4 CKD

A range of medications can help manage CKD symptoms and slow progression.

These drugs might include:

• Medications to address underlying conditions: A doctor might prescribe angiotensin converting enzyme inhibitors or angiotensin II receptor blockers to manage high blood pressure. A doctor might also recommend drugs for managing blood sugar levels.
• Supplements for bone strength: Vitamin D and calcium supplements can help maintain and protect bone strength. They may also reduce the risk of bone disease from kidney damage.
• Diuretics: These medications can help to reduce edema and help with urination.
• Medications and supplements for anemia: Erythropoiesis-stimulating agents and iron supplements can help manage anemia.

Stage 4 CKD diet

A nephrologist may refer someone with stage 4 CKD to a dietitian. A dietitian can help a person with CKD optimize their diet to protect their kidney health. A person with stage 4 CKD may benefit from:

• eating more fresh, whole foods
• eating less salt
• eating smaller portions of high protein foods
• choosing heart-healthy foods and limiting saturated and trans fats
• limiting or avoiding alcohol
• eating foods lower in phosphorus and potassium

Discussing next steps

A nephrologist might explain the next stages of treatment depending on kidney function and a person’s eGFR. If they believe kidney failure is a likely outcome, a doctor may want to discuss:

• Dialysis: In this treatment, a person with kidney failure has an external machine filter their blood. The machine then returns the filtered blood to the body.
• Kidney transplant: This involves surgery to transfer a healthy kidney from one person to another.

Regular consultations and monitoring a person’s blood glucose, blood pressure, and eGFR readings all help a nephrologist determine a person’s risk of CKD progression.

There is no way to reverse or fix kidney damage. However, several factors can contribute to how long a person with CKD may live, including:

• a person’s age at the time of diagnosis
• other health conditions they may have
• how closely a person follows their treatment plan

A person with stage 4 CKD can speak with a healthcare professional about their individual outlook.

Around 9 in 10 people with CKD are not aware they have it, meaning that it can sometimes be unclear when to seek medical attention.

However, by stage 4, symptoms of CKD are likely to become clearer. Experts advise people to contact a doctor if they notice any symptoms of CKD.

People with diabetes or high blood pressure should receive regular consultations with their doctor to ensure neither condition causes CKD.

Stage 4 CKD is the last stage of the condition before kidney failure occurs in stage 5. A person with stage 4 CKD may have symptoms, such as foamy urine and edema.

Diabetes and high blood pressure are common causes of CKD, but other causes may also lead to the condition.

It is possible to slow CKD progression by following a nephrologist’s recommendations. However, people with stage 4 CKD may need to start dialysis or receive a kidney transplant if their kidney function declines.