Chronic Kidney Disease

Introduction

Chronic kidney disease (CKD) refers to the gradual loss of kidney function, which affects the kidneys’ ability to perform essential tasks, including:

• Filtering blood: Removing waste products, toxins, acids, and excess water from the bloodstream.
• Regulating nutrients: Managing vitamins and minerals that are crucial for maintaining bone health.
• Hormone production: Releasing hormones that stimulate the production of red blood cells.

Staging of Chronic Kidney Disease

The stage of CKD in a child is primarily determined by the glomerular filtration rate (GFR), which measures kidney function. The National Kidney Foundation in the USA classifies CKD into five stages based on GFR values:

• Stage 1: GFR > 90 ml/min/1.73 m²
• Stage 2: GFR 60-89 ml/min/1.73 m² (mild decrease in kidney function)
• Stage 3: GFR 30-59 ml/min/1.73 m² (moderate decrease in kidney function)
• Stage 4: GFR 15-29 ml/min/1.73 m² (severe decrease in kidney function)
• Stage 5: GFR < 15 ml/min/1.73 m² (kidney failure)

This classification serves as a guide only, as symptoms can vary among children. Traditionally, kidney failure was defined as a loss of more than 85% of kidney function, typically requiring kidney replacement therapy, such as dialysis or transplantation.

Causes

About half of the cases of CKD in children are attributed to congenital abnormalities of the kidneys, urinary tract, and bladder, which are present from birth. These congenital issues can lead to various complications, including:

• Obstruction of blood flow: This can damage the kidneys by restricting blood flow.
• Vesicoureteral reflux: This condition occurs when urine flows backward from the bladder to the kidneys, causing potential kidney damage.
• Dysplastic kidneys: These are kidneys that never form correctly and therefore cannot function properly.
• Obstruction of urine outflow: Conditions such as posterior urethral valves can block urine flow, leading to kidney damage.

The other half of CKD cases in children arise from acquired causes that can also lead to kidney damage, including:

• Glomerular diseases: Causing blood or protein to leak into the urine, often accompanied by body swelling due to low protein levels in the blood.
• Recurrent urinary tract infections
• Systemic diseases: Conditions such as systemic lupus erythematosus or other autoimmune disorders can adversely affect kidney function.
• Certain types of cancers
• Medications or treatments for other conditions

Signs and Symptoms

Recognizing CKD in children can be challenging, especially in the early stages when symptoms may be minimal or absent. Some common symptoms that may eventually appear include:

• Fatigue: Children may feel unusually tired
• Pale appearance: A noticeable paleness can occur due to anaemia
• Nausea and vomiting
• Poor growth
• Severe itchiness: Itching can result from the buildup of waste products in the blood

Diagnosis

The diagnosis of CKD in children depends on the symptoms presented and the doctor's judgement. The following tests may be conducted to assess kidney function and identify any underlying issues:

• Urinalysis: This test checks for the presence of blood or protein in the urine, which can indicate kidney damage.
• Blood pressure measurement: Hypertension is a common complication of CKD.
• Blood tests: These tests evaluate kidney function and may include measurements of haemoglobin levels, blood gases, minerals, hormones, and other relevant parameters.
• Kidney biopsy: If glomerular disease is suspected, a kidney biopsy may be performed to obtain a small sample of kidney tissue for examination under a microscope.
• Kidney ultrasound: This non-invasive imaging test assesses the size and shape of the kidneys and can detect abnormalities such as masses, stones, cysts, or obstructions.
• Nuclear medicine scan: This painless test evaluates kidney function and can reveal any obstructions.

Management

General

For children in the earlier stages of CKD (stages 1 to 3), symptoms may be minimal. However, regular monitoring and proactive treatment are essential to slow the progression of the disease. The management strategies include

• Blood pressure control: Maintaining tight control of blood pressure can significantly slow down the progression of kidney impairment.
• Acidosis management: As kidney function declines, the kidneys may struggle to excrete acids, leading to acid accumulation. Alkali therapy, such as oral sodium bicarbonate, can help correct acid levels in the blood.
• Anaemia treatment: Anaemia is a common complication in CKD. To address this, iron supplementation or injection of erythropoietin may be necessary to promote red blood cell production.
• Support for growth: Dietary advice will be provided, and some children may require growth hormone injections.
• Anti-proteinuria medications: To mitigate protein loss in urine, which can further decline kidney function, specific medications will be prescribed.

Special follow-up care in HKCH

At stages 4 and 5 of CKD, children may experience more pronounced symptoms, and doctors may begin discussing the need for kidney replacement therapy. At this point, kidney function may decline to less than 15%, making it difficult to maintain good health despite conservative treatment measures.

HKCH is the only tertiary referral centre in Hong Kong that offers various kidney replacement therapies for children, including haemodialysis, peritoneal dialysis and kidney transplant.

At HKCH, we adopt a multidisciplinary approach to support children throughout their lifelong journey with CKD. Our multidisciplinary team includes paediatricians, nurses, paediatric surgeons, urologists, pharmacists, dieticians, occupational therapists, physiotherapists and medical social workers. This collaborative approach ensures that each child receives a comprehensive assessment and tailored management plan, enabling them to lead a happy and fulfilling life as much as possible.

Useful Resources

Children's Kidney Fund

Chronic Kidney Disease Early Identification and Intervention in Primary Care

Acknowledgement

Principal author: Dr Alice Chuah on behalf of Nephrology Team, HKCH

Initial posting: Nov 2025

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