Patients may experience fatigue, mental status changes, dehydration, or symptoms of nephrolithiasis in humoral hypercalcemia of malignancy , is when the serum calcium level is more than:

Humoral hypercalcemia of malignancy (HHM) Humoral hypercalcemia of malignancy (HHM) occurs in 20% of cancer. It is commonly seen in cancers of the lung, head and neck, esophagus, breast, genitourinary tract and in multiple myeloma & lymphomas. Caused most commonly by overproduction of PTHrP When the calcium levels are markedly increased >14 mg/dL patients may experience fatigue, mental status changes, dehydration, symptoms of nephrolithiasis. Ref: Harrison,E-18,P-828