Based on PubMed | Can testicular cancer cause high calcium on blood tests, and what serum calcium levels are considered high?

Testicular cancer and high calcium: what to know

Yes testicular cancer can be associated with high calcium (hypercalcemia), although this is uncommon. Hypercalcemia in cancer generally arises through a few mechanisms: tumor secretion of parathyroid hormone–related protein (PTHrP), excess vitamin D activity (calcitriol) produced by tumor or immune cells, or bone breakdown from metastases. ^[1] In germ cell tumors such as seminoma, rare cases of “humoral” hypercalcemia have been reported, often with normal parathyroid hormone (PTH) and inappropriately elevated calcitriol; calcium levels typically normalize with effective chemotherapy against the tumor. ^[2] More broadly across cancers, PTHrP-driven hypercalcemia is recognized as a major cause of malignancy‑associated hypercalcemia when bone metastases are not prominent. ^[3]

How cancer causes high calcium

• PTHrP secretion: Many solid tumors can release PTHrP, which acts like PTH to increase bone resorption and reduce renal calcium excretion, raising blood calcium. ^[1] PTHrP is frequently detected in tumors from patients with humoral hypercalcemia of malignancy and correlates with the syndrome. ^[4]
• Excess calcitriol (vitamin D): Some malignancies raise calcitriol, increasing intestinal calcium absorption; this has been described in seminoma‑related hypercalcemia. ^[2]
• Osteolytic bone disease: Cancers that spread to bone can cause local bone breakdown, releasing calcium into the blood. ^[5]

What calcium level is considered high?

• Total serum calcium: In most adult labs, a typical reference range is about 8.5–10.2 mg/dL (2.12–2.55 mmol/L). Levels above this range are generally considered elevated. ^[6]
• Ionized calcium (the active form): Adult reference range is commonly around 4.8–5.6 mg/dL (1.20–1.40 mmol/L). Values above this range indicate ionized hypercalcemia. ^[7]
• Clinical tiers used in practice often describe mild hypercalcemia near the upper limit of normal, moderate elevations in the 11–13 mg/dL range, and severe elevations above that; any significant elevation warrants medical evaluation, especially if symptoms are present. ^[6]

Symptoms to watch for

Hypercalcemia may cause increased thirst and urination, nausea, constipation, abdominal pain, fatigue, muscle weakness, confusion, and in severe cases heart rhythm problems; very high levels can be a medical emergency requiring urgent treatment. ^[8] When hypercalcemia is due to cancer, treatments may include IV fluids, anti‑resorptive medicines like IV bisphosphonates or denosumab, and other measures tailored to the cause, alongside therapy for the underlying cancer. ^{[9] [10]}

Key takeaways

• Testicular cancer can be linked to high calcium, but this is rare; when it happens, it is often due to tumor‑driven hormonal effects such as PTHrP or calcitriol. ^{[1] [2]}
• For adults, total calcium above roughly 10.2 mg/dL or ionized calcium above about 5.6 mg/dL is generally considered high by typical laboratory standards. ^{[6] [7]}
• If calcium is elevated, measuring PTH, PTHrP, and vitamin D metabolites can help identify whether the cause is parathyroid disease, PTHrP‑mediated cancer effects, or calcitriol excess. ^{[1] [3]}

Would you like to share your most recent calcium value and whether PTH or vitamin D levels have been checked?