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Hypercalcaemia of Malignancy: A Hidden but Serious Cancer Complication
By Dr. Gajendra Kumar Himanshu
Hypercalcaemia of malignancy is a condition in which cancer causes the calcium level in the blood to become abnormally high. It can occur when cancer affects the bones or produces substances that increase blood calcium. Symptoms may include excessive thirst, frequent urination, constipation, nausea, weakness, confusion, and fatigue. Severe hypercalcaemia can affect the kidneys, heart, and nervous system and requires prompt medical treatment.
In this blog, we are talking about hypercalcaemia of malignancy, why it develops, which cancers are commonly associated with it, the symptoms patients should watch for, how doctors diagnose it and how it is treated. We will also explain why early recognition matters and what patients should discuss with their oncology team.
Why hypercalcaemia of malignancy matters
Hypercalcaemia means that the blood contains more calcium than normal. Calcium is essential for healthy bones, muscles, nerves, and many other body functions, but too much can interfere with several organs. In people with cancer, hypercalcaemia can become a serious complication that requires urgent assessment and treatment.
The condition may develop because cancer has spread to the bones and increased bone breakdown, or because some tumors produce substances that increase calcium levels. It can sometimes develop without obvious symptoms at first, which is why blood tests are important when doctors suspect it.
What causes hypercalcaemia of malignancy?
Cancer can raise blood calcium through several mechanisms, and the exact cause depends on the type and behaviour of the tumor.
Cancer spread to the bones
When cancer spreads to bone, it can disrupt the normal balance between bone formation and breakdown. Increased breakdown of bone can release calcium into the bloodstream. Multiple myeloma is one example of a cancer in which bone damage can contribute to hypercalcaemia.
Tumor-produced substances
Some cancers produce hormone-like substances, particularly parathyroid hormone-related protein, which can increase calcium levels. This mechanism is sometimes referred to as humoral hypercalcaemia of malignancy.
Increased vitamin D activity
Certain cancers, especially some lymphomas, can increase the production or activity of vitamin D-related compounds, which can raise calcium absorption from the digestive tract and contribute to hypercalcaemia.
Which cancers can cause hypercalcaemia?
Hypercalcaemia can occur with different cancers, especially advanced cancers and cancers that commonly affect bone.
Multiple myeloma
Multiple myeloma can damage bone and increase the release of calcium into the blood. Hypercalcaemia may occur along with bone pain, fractures and kidney problems.
Breast and lung cancer
Breast and lung cancers can cause hypercalcaemia, particularly when the disease has advanced. Cancer that spreads to the bones can contribute to increased calcium release.
Other cancers
Kidney cancer, certain head and neck cancers and some lymphomas can also be associated with high calcium levels. The underlying mechanism may differ from one cancer to another.
What are the symptoms of hypercalcaemia?
The symptoms can be mild at first and may be mistaken for other problems. As calcium levels rise, symptoms can become more noticeable.
Symptom | What may happen |
|---|---|
Excessive thirst and frequent urination | High calcium can affect kidney function and may cause increased thirst and frequent urination. This can contribute to dehydration, which may make the condition worse. |
Digestive symptoms | Nausea, vomiting, poor appetite and constipation are common symptoms of hypercalcaemia. These symptoms may also occur because of cancer or treatment, so blood testing may be needed to identify the cause. |
Weakness and severe fatigue | Patients may experience muscle weakness, tiredness and reduced energy. In more severe cases, the effects can interfere significantly with normal daily activities. |
Confusion and changes in thinking | High calcium can affect the nervous system and may cause restlessness, confusion, drowsiness or difficulty thinking clearly. Severe neurological changes require urgent medical attention. |
When should hypercalcaemia be treated urgently?
Severe or rapidly worsening symptoms should not be ignored. Confusion, extreme weakness, persistent vomiting, severe dehydration, reduced alertness or other major changes in mental or physical function may indicate significant hypercalcaemia.
Patients with cancer who develop new symptoms such as excessive thirst, frequent urination, severe constipation, nausea, weakness or confusion should contact their healthcare team rather than assuming that the symptoms are simply part of the cancer or its treatment.
How is hypercalcaemia of malignancy diagnosed?
Diagnosis usually begins with a blood test measuring calcium. Doctors may also check albumin, kidney function and other blood results to understand the severity and possible cause.
Depending on the clinical situation, additional tests may include parathyroid hormone measurements, vitamin D-related tests and investigations to determine whether bone involvement or another cancer-related mechanism is responsible.
The underlying cancer may also need reassessment through imaging or other investigations if there is concern that it has progressed.
How is hypercalcaemia of malignancy treated?
Treatment has two main goals: lower the calcium level safely and control the underlying cancer.
Fluids and medicines
Intravenous fluids are commonly used to correct dehydration and help the kidneys remove excess calcium. Doctors may then use medicines that reduce bone breakdown or otherwise lower calcium. Bisphosphonates such as pamidronate and zoledronic acid are established treatments for malignancy-associated hypercalcaemia. Denosumab is also approved for hypercalcaemia of malignancy that has worsened after bisphosphonate treatment.
Treating the underlying cancer
Controlling cancer is an important part of long-term management. Depending on the primary cancer, treatment may include chemotherapy, targeted therapy, immunotherapy, hormone therapy, radiation or other cancer-specific treatment. Managing the underlying disease can help reduce the risk of recurrent hypercalcaemia.
Can hypercalcaemia of malignancy come back?
Yes, hypercalcaemia can return if the underlying cancer remains active or progresses. The risk depends on the cancer type, extent of disease and response to treatment.
For this reason, patients may need repeated blood calcium measurements, kidney-function monitoring and ongoing cancer treatment. Regular follow-up allows doctors to identify rising calcium levels before symptoms become severe.
What should patients ask their oncology team?
Patients can ask what their calcium level is, what may be causing the elevation, whether kidney function is affected and which treatment is being recommended. It is also useful to understand whether the cancer has involved the bones and whether additional tests are needed.
If treatment includes medicines that affect calcium or bone metabolism, ask how often blood tests will be performed and which symptoms should prompt an urgent call to the healthcare team.
For more information regarding malignancy-related hypercalcaemia, visit the National Library of Medicine.
Consult Today
If you or a loved one with cancer develops excessive thirst, frequent urination, constipation, nausea, unusual weakness or confusion, discussing these symptoms promptly with the oncology team is important. At Oncare Cancer Hospital, patients can receive specialist evaluation for cancer-related complications such as hypercalcaemia and understand the investigations and treatment options appropriate to their condition.
Disclaimer
This blog is for educational purposes only and does not replace professional medical advice, diagnosis or treatment. Hypercalcaemia of malignancy requires individual evaluation to determine its cause and severity. Consult a qualified doctor for personalised advice.
Frequently Asked Questions
Hypercalcaemia of malignancy is an abnormally high level of calcium in the blood caused by cancer. It may occur because cancer affects the bones or because tumor cells produce substances that increase calcium levels.
Common symptoms include excessive thirst, frequent urination, constipation, nausea, vomiting, poor appetite, weakness, fatigue and confusion. Severe hypercalcaemia can affect the kidneys, nervous system and other organs.
Hypercalcaemia can occur with several cancers, including multiple myeloma, breast cancer, lung cancer and some lymphomas. The cause may be related to bone involvement or substances produced by the tumor.
Yes, treatment may include intravenous fluids and medicines such as bisphosphonates or denosumab, along with treatment of the underlying cancer. The approach depends on the severity of hypercalcaemia and the patient's overall condition.
Written and Verified by:
Dr. Gajendra Kumar Himanshu Exp: 10 Yr
Medical Officer
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