Hypercalcemia (Differential Diagnoses)

Serum levels of total and ionized calcium

-serum total calcium > 12mg/dl

-serum ionized calcium > 1.4 mmol/l

3 things calcium is regulated by

Vitamin D (calcitriol), calcitonin, parathyroid hormone

PTH effects on calcium

-increased mobilization of Ca and P from bone

-phosphate excretion and calcium retention by the kidneys (increased Ca, decreased P)

Calcitriol effect on Ca

-increased Ca absorption from the intestines and results in increased P as well

Calcitonin effect on Ca

-inhibits Ca absorption by inhibiting osteoclastic bone resorption

Clinical signs of hypercalcemia

-PU/PD

-anorexia

-depression, weakness

-vomiting

-constipation

-arrhythmias

-seizures, muscle tremors

-seen when levels are >15mg/dl

-animals with levels > 18 mg/dl may be more debilitated

GOSH DARN IT pneumonic for differentials

G- granulomatous disease, growing young dog

O - osteolytic disease (osteomyelitis, neoplasia)

S- spurious (lipemic, post prandial blood sample, lab erorr, hemolysis)

H - Hyperparathyroidism (primary)

D - Drugs (thiazine, calcium containing phosphate binders)

A - Addison’s disease (hypoadrenocortisicm)

R - renal failure (acute or chronic)

N - nutritional (hypervitaminosis D from drugs, cholecalciferol rodenticide, poisonous plants, hypervitaminosis A, or excess Ca)

I - Idiopathic (mainly cats)

T - tumors → humoral hypercalcemia of malignancy (lymphoma, apocrine gland anal sac adenocarcinoma)

-bone osteolysis: multiple myeloma, lymphoma, bony neoplasia

Important aspects of physical exam

-rectal exam

-lymph nodes

-mammary chain palpation

-orthopedic exam

CBC, chem profile, urinalysis examination

-asses BUN/creatinine for renal function

-Asses electrolytes (Na:K ratio <27:1 = Addison’s)

-hyperglobulinemia - myeloma or lymphoma

Diagnostic Imaging assessment

-thoracic x rays → hilar lymphadenopathy, granulomatous pulmonary disease, lytic bone lesion

3 Other tests for suspicion of hypoadrenocortisicm, hyperparathyroidism, neoplasia, idiopathic

-ACTH stim - Addison’s

-cervical ultrasound or CT/MRI to assess parathyroid glands

-PTH-rp levels for humoral hypercalcemia of malignancy

Options for treating symptoms of hypercalcemia (6)

-IV fluid diuresis (0.9% NaCl)

-Furosemide promotes calciuresis but only give to hydrated patients (avoid thiazides)

-Prednisone or dexamethasone are glucocorticoids that promote calciuresis and decrease bone resorption and intestinal absorption of calcium (admin to a lymphoma candidate can hamper diagnosis and decrease effectiveness of eventual treatment, avoid if unknown diagnosis)

-bisphosphonates - inhibit osteoclastic activity

-calcitonin - mainly used for hypervitaminosis D (replaced mostly by bisphophonates)

-sodium bicarbonate - decreases ionized calcium which is responsible for most signs (usually only ER tx)