What should you know about lung cancer causing hypercalcemia?

Hypercalcemia means there is too much calcium in the bloodstream. Some lung tumours release hormone-like signals that alter the balance between bone, kidneys and the gut. Cancer involving bone can also release calcium as bone is affected. Other causes, including medicines or parathyroid problems, are possible, so a blood result does not by itself identify the cause.

Symptoms may include thirst, frequent urination, constipation, nausea, abdominal discomfort, muscle weakness, tiredness or difficulty thinking clearly. Clinicians usually repeat or confirm blood tests, review kidney function and medicines, and investigate the cancer and bones when needed. [Lung Cancer](/conditions/lung-cancer/) assessment may include scans and a tissue diagnosis.

Tell your oncology team about increasing thirst, reduced appetite, constipation, vomiting, drowsiness or changes in concentration. Do not start calcium supplements or stop prescribed medicines without checking first. Your clinician may recommend fluids, medicines that lower blood calcium, and treatment directed at the underlying cancer.

The plan depends on symptoms, blood results, kidney health and the cancer’s features. It may involve systemic treatment, [Radiotherapy](/treatments/radiation-oncology/radiotherapy/) for a painful bone area, or supportive [Palliative Care](/treatments/supportive-and-palliative-care/palliative-care/) alongside cancer treatment. [Genomic Tumour Profiling](/treatments/diagnostics-and-staging/genomic-tumour-profiling/) can sometimes help identify treatment options.

Seek urgent care for confusion, unusual sleepiness, repeated vomiting, inability to keep fluids down, fainting, severe weakness, very little urine or a new severe heartbeat disturbance. These symptoms can reflect a significant calcium or kidney problem and should not wait for a routine appointment. New seizures, weakness on one side or trouble speaking are also emergencies; [Brain Metastases](/conditions/brain-metastases/) provides related context.

Ask what your calcium result means, whether it has been corrected for blood proteins, what may be causing it, and when it should be rechecked. Ask which fluids or medicines are planned, what kidney monitoring is needed, and which cancer treatment could reduce recurrence of the problem.