Table: Characteristic Laboratory Abnormalities Associated with Common Causes of Hypercalcemia

Characteristic Laboratory Abnormalities Associated with Common Causes of Hypercalcemia

Diagnosis	Total Calcium	Ionized Calcium	Intact PTH	1,25-Dihydroxyvitamin D	Phosphorus	PTHrP
Primary hyperthyroidism	High	High	Normal to high	Normal	Normal to low	Negative
Malignant hypercalcemia	High	High	Low to low- normal	Low to normal	Normal to low	Positive (sometimes)
Hypoadrenocorticism (Addison disease)	Low, normal, or high	Normal	Normal	Normal	Normal to high	Negative
Chronic renal failure	Low, normal, or high	Normal to low	Normal to high	Low to normal	High	Negative
Hypervitaminosis D (calcitriol or calcitriol analogue)	High	High	Low to low- normal	Low to normal	Normal to high	Negative
Hypervitaminosis D (D₂ or D₃ toxicity)	High	High	Low to low- normal	High	Normal to high	Negative
Granulomatous disease	High	High	Low to low- normal	Low to normal	Normal to high	Negative
Idiopathic hypercalcemia of cats	High	High	Normal	Normal	Normal	Negative