Tumour markers in children — AFP, beta-hCG, catecholamines & LDH explained

A tumour marker is a substance — usually a protein or a hormone metabolite — that certain cancer cells produce in larger-than-normal amounts. When a doctor suspects a specific type of childhood cancer based on symptoms, physical examination, or imaging, a blood or urine test for the relevant marker is ordered to gather supporting evidence. In children, tumour markers are particularly useful for cancers that arise from immature tissue, such as hepatoblastoma (liver), neuroblastoma (nerve tissue), and germ cell tumours (ovary, testis, or midline). No tumour marker is diagnostic on its own — a raised result must always be interpreted alongside scans, clinical findings, and ultimately biopsy or histology. But a clearly elevated marker in the right clinical context speeds up diagnosis and reduces the number of invasive tests needed.

AFP is a protein produced naturally by the developing liver and yolk sac in foetal life. After birth, AFP levels fall rapidly and should reach adult-low levels by around 12 months of age. In a child older than one year, a clearly elevated AFP is abnormal and raises concern for hepatoblastoma (the most common liver tumour in children) or a germ cell tumour with a yolk-sac component. The critical point for parents is this: AFP is age-dependent. A result that looks high compared to an adult reference range may be entirely normal in a baby under six months. Your child's oncologist will always compare the result to age-appropriate norms, not the adult reference printed on the lab report. If the AFP is genuinely elevated for the child's age, the next step is usually liver ultrasound or cross-sectional imaging, not immediate biopsy.

Catecholamines are a family of chemicals that include adrenaline and noradrenaline. They are produced by nerve tissue throughout the body. Neuroblastoma — a tumour that arises from immature nerve cells, most commonly in the abdomen or adrenal gland — is made of cells that produce these chemicals in excess. The excess is measured indirectly via two breakdown products in the urine: vanillylmandelic acid (VMA) and homovanillic acid (HVA). The test requires a 24-hour urine collection or a single spot urine sample, depending on the lab's protocol. Elevated VMA and HVA in a child with an abdominal mass is a strong pointer to neuroblastoma. The test is non-invasive, painless, and reproducible, making it useful both for initial diagnosis and for monitoring response to treatment.

LDH is an enzyme found inside virtually all cells in the body. When cells are damaged or are dividing rapidly — as happens in cancer — they release LDH into the bloodstream, raising the serum level. In childhood cancer, LDH is not specific to one tumour type. It is elevated in leukemia, lymphoma, neuroblastoma, Ewing sarcoma, and many other cancers. Because of this lack of specificity, LDH is used as a disease-burden marker rather than a diagnostic marker. A very high LDH at diagnosis generally indicates a larger or more aggressive tumour burden and helps oncologists plan treatment intensity. During treatment, a falling LDH is often a reassuring sign that the cancer is responding. LDH is also commonly raised by infections, muscle damage, and liver disease, so the result is never interpreted in isolation.

No. A normal tumour marker result does not rule out cancer. Many childhood cancers do not produce any detectable marker — including most brain tumours, Wilms tumour of the kidney, and the majority of bone sarcomas. Even for cancers where markers are relevant, not every case produces elevated levels at the time of initial testing. Markers are one piece of evidence among many. If your child's doctor is concerned based on symptoms, examination, or imaging, a normal marker result should not stop further investigation. Equally, a mildly elevated marker in a well child without worrying symptoms often has a completely benign explanation. The clinical picture — history, examination, scans, and specialist review — drives decisions, not a single number.

The next steps depend on which marker is raised, by how much, and what clinical features are present. In most cases, an abnormal marker triggers imaging — usually an ultrasound first, then CT or MRI depending on what the ultrasound shows. If imaging reveals a mass or abnormality, the child is referred urgently to a paediatric oncologist. From there, the pathway usually involves further blood tests to assess organ function, a tumour board review of all findings, and a biopsy or surgical procedure to obtain tissue for definitive diagnosis. At CION, every case with a raised childhood tumour marker is reviewed by a multidisciplinary team before any invasive step is taken. We take time to explain each step to you, answer your questions fully, and walk this journey alongside your family.